assessment of cadmium flows related to domestic activities and proposal of recovery solutions

DRESDEN UNIVERSITY OF TECHNOLOGY VNU UNIVERSITY OF SCIENCENgo Van Anh ASSESSMENT OF CADMIUM FLOWS RELATED TO DOMESTIC ACTIVITIES AND PROPOSAL OF RECOVERY SOLUTIONS MASTER THESIS Hanoi

DRESDEN UNIVERSITY OF TECHNOLOGY VNU UNIVERSITY OF SCIENCE

Ngo Van Anh

ASSESSMENT OF CADMIUM FLOWS RELATED TO DOMESTIC ACTIVITIES AND PROPOSAL OF RECOVERY SOLUTIONS

MASTER THESIS

Hanoi - 2011

DRESDEN UNIVERSITY OF TECHNOLOGY VNU UNIVERSITY OF SCIENCE

Ngo Van Anh

ASSESSMENT OF CADMIUM FLOWS RELATED TO DOMESTIC ACTIVITIES AND PROPOSAL OF RECOVERY SOLUTIONS

Major: Waste Management and Contaminated Site Treatment

MASTER THESIS

SUPERVISOR: ASSOC PROF DR NGUYEN THI HA

ABSTRACTS

This thesis analyses the flows of cadmium (Cd) concerning with domestic activities in 3 communes (Co Loa, Tho Xuan and Duong Lieu), especially at Co Loa using MFA (Material flow analysis) or SFA (substance flow analysis) as a framework MFA/SFA allows all material/substance inflows, outflows, and stocks through each sub-compartment in 3 communes to be examined

The results of the thesis were visualized and presented in diagrams, including

an aggregate diagram Existing data from a large variety of sources was utilised to complete all cadmium flows within each commune Cadmium sources are linked to activities of households, markets, agricultural production and on-site sanitation system A large content of cadmium found in daily domestic solid waste Phosphate fertilizers and animal manure have been identified as other significant inputs to agricultural soils Based on the findings, appropriate solutions for cadmium recovery were suggested

ACKNOWLEDGEMENT

My profound gratitude of course reserves for my parents and my relatives who always create good conditions for me to pursue my education Their expectation and support have sustained me during the whole period of my study

I am most indebted to my supervisor Assoc Prof Dr Nguyen Thi Ha Thank you for your patience and for providing consistent direction, encouragement, and constructive guidance for my thesis

I also would like to thank Prof Bernd Bilitewski, Prof Peter Werner, Assoc Prof Dr Bui Duy Cam, and Assoc Prof Dr Nguyen Thi Diem Trang for their significant role in organization and support this course

Finally, I would like to express my sincere gratitude to my friends who spent their time helping me do my thesis

TABLE OF CONTENT

ABSTRACTS 1

ACKNOWLEDGEMENT 2

TABLE OF CONTENT 3

LIST OF TABLES 5

LIST OF FIGURES 7

ABBREVIATIONS 8

INTRODUCTION 9

CHAPTER 1 – LITERATURE REVIEW 11

1.1 Overview of cadmium usage and environmental concerns 11

1.1.1 Sources and emissions 11

1.1.2 Fate, transport and transformation of cadmium in environment 16

1.1.3 Effect of cadmium on human health and environment 18

1.2 Overview of MFA 21

1.2.1 Terminology used in MFA 22

1.2.2 MFA procedure 24

1.2.3 Application of MFA 25

1.2.4 Some MFA case studies 27

CHAPTER 2 – APPROACH AND METHODOLOGY 38

2.1 Description of study area and scope 38

2.1.1 Co Loa commune 38

2.1.2 Tho Xuan commune 40

2.1.3 Duong Lieu commune 41

2.2 Methodology 42

2.2.1 System analysis 43

2.2.2 Data collection 43

2.2.3 Modelling approach 44

CHAPTER 3 - RESULTS 46

3.1 Result of cadmium flows identification (qualitative analysis) 46

3.1.1 Co Loa commune 46

3.1.2 Tho Xuan commune 49

3.1.3 Duong Lieu commune 53

3.2 Result of Cd flows calculation (quantitative analysis) 57

3.2.1 Cd flows calculation concerning with the activities in households 57

3.2.2 Cd flows calculation concerning with the activities in markets 61

3.2.3 Cd flows calculation concerning with industry 64

3.2.4 Cd flows calculation concerning with farmland 65

3.2.5 Cd flows calculation concerning with livestock 68

3.2.6 Cd flows calculation concerning with aquaculture 70

3.2.7 Cd flows calculation concerning with S&D 72

3.2.8 Cd flows calculation concerning with on-site sanitation 75

3.2.9 Cd flows calculation concerning with biogas 79

3.2.10 Cd flows calculation concerning with intermediate waste storage 80

3.2.11 Quantitative diagram 81

3.3 Proposal of Cd recovery solutions 82

3.3.1 Solutions to recover Cd in solid waste 82

3.3.2 Solutions to recover Cd in liquid waste 85

CONCLUSIONS 88

REFERENCES 90

ANNEXES 95

LIST OF TABLES

Table 1 Range in BRCs of Cd for fine-grained marine sediments, seawater and blue

mussel within the OSPAR area 12

Table 2 Cadmium and its compounds emissions to air, land and water 15

Table 3 Main physico-chemical properties and registration numbers of Cd 16

Table 4 Cadmium intake for members of the public (1994) 19

Table 5 Amount of phosphate ore was mined in some countries during 2005 32

Table 6 Cultivation productivity in Co Loa in 2009 39

Table 7 Breeding productivity in Co Loa in 2009 39

Table 8 Cadmium flows from domestic activities in Co Loa commune 46

Table 9 Cadmium flows from domestic activities in Tho Xuan commune 50

Table 10 Cadmium flows from domestic activities in Duong Lieu commune 54

Table 11 Variables in HH activity 57

Table 12 Values for calculation of Cd flows in HH activity 59

Table 13 Summary for Cd flows calculation concerning with activities in HH 61

Table 14 Variables in markets activity 62

Table 15 Values for calculation of Cd in markets activity 62

Table 16 Summary for Cd flows calculation concerning with activities in markets 63 Table 17 Variables in industry activity 64

Table 18 Values for calculation of Cd flows in industry activity 64

Table 19 Summary for Cd flows calculation concerning with industry 65

Table 20 Variables in farmland activity 66

Table 21 Values for calculation of Cd flows in farmland activity 66

Table 22 Summary for Cd flows calculation concerning with farmland 67

Table 23 Variable in livestock activity 68

Table 24 Values for calculation of Cd flows in livestock activity 69

Table 25 Summary for Cd flows calculation concerning with livestock 70

Table 26 Variables in aquaculture activity 71

Table 27 Values for calculation of Cd flows in aquaculture activity 71

Table 28 Summary for Cd flows calculation concerning with aquaculture 71

Table 29 Variables in S&D activity 72

Table 30 Values for calculation of Cd flows in S&D 73

Table 31 Summary for Cd flows calculation concerning with S&D 75

Table 32 Variables in septic tank system 76

Table 33 Values for calculation of Cd flows in septic tank system 76

Table 34 Variables in double vaults toilet system 77

Table 35 Values for calculation of Cd flows in double vaults toilet system 77

Table 36 Variables in on-site sanitation activity 78

Table 37 Summary for Cd flows calculation concerning with on-site sanitation 78

Table 38 Variables in biogas activity 79

Table 39 Values for calculation of Cd flows in biogas activity 79

Table 40 Summary for Cd flows calculation concerning with biogas 80

Table 41 Variables in intermediate waste storage activity 80

Table 42 Values for calculation of Cd flows in intermediate waste storage activity 80 Table 43 Summary for Cd flows calculation concerning with intermediate waste storage 81

LIST OF FIGURES

Fig 1 Graphical representation of an MFA system 24

Fig 2 MFA procedure 25

Fig 3 Co Loa commune 38

Fig 4 Tho Xuan commune 40

Fig 5 Duong Lieu commune 41

Fig 6 Protocol for substance flow analysis 42

Fig 7 System analysis of domestic activities in Co Loa 49

Fig 8 System analysis of domestic activities in Tho Xuan 53

Fig 9 System analysis of domestic activities in Duong Lieu 56

Fig 10 Input and output flows concerning with household activity 57

Fig 11 Input and output flows concerning with markets activity 61

Fig 12 Input and output flows concerning with industry activity 64

Fig 13 Input and output flows concerning with farmland activity 65

Fig 14 Input and output flows concerning with livestock activity 68

Fig 15 Input and output flows concerning with aquaculture activity 70

Fig 16 Input and output flows concerning with S&D activity 72

Fig 17 Input and output flows concerning with on-site sanitation activity 75

Fig 18 Input and output flows concerning with septic tank system 76

Fig 19 Input and output flows concerning with double vaults toilet system 77

Fig 20 Input and output flows concerning with biogas activity 79

Fig 21 Input and output flows concerning with intermediate waste storage activity80 Fig 22 Quantitative diagram for Cd flows in Co Loa commune 82

ELM Emulsion liquid membranes

FAO Food and Agriculture Organization

GESAMP Joint Group of Experts on the Scientific Aspects of

MFA Material flow analysis

OECD Organization for Economic Co-operation and

Development PVC Polyvinyl chloride

SFA Substance flow analysis

S&D Sewer and drainage system

The OSPAR Convention The Convention for the Protection of the Marine

Environment of the North-East Atlantic

US EPA United State Environmental Protection Agency

WHO World Health Organization

INTRODUCTION

Cadmium is usually found in trace amounts as a component of the surface soil, sediments and surface water, and in the air However, most of the cadmium in the environment results directly from human activities Cadmium is not essential to living organisms It enters the human body via food, smoking, and inhalation of contaminated air It is extremely dangerous as it is easily absorbed and remains in the tissues for a long time Because of the slow rate of cadmium excretion, levels in the body increase with age in situations of chronic exposure Human kidney disease (renal dysfunction) is one result of such long-term exposure (WHO 1992)

Assessment of cadmium flows by material flow analysis method originally developed by Baccini and Brunner, 1991; can provide a holistic picture of resource use and loss in a geographic region in a specific year In industrialized countries, MFA proved to be a suitable instrument for the early recognition of environmental problems and development of countermeasure It can be applied to analyze resource flows in a city, particularly to evaluate the impact of changes in consumption patterns, solid waste and wastewater treatment infrastructure, peri-urban agricultural production, including waste and wastewater reuse practices on resource consumption and environmental pollution It also provides useful information for planners and decision-makers and could help improve resource management of areas in developing countries However, limited data availability, reliability and data collection means (available laboratory equipment, trained laboratory staff, financial and human resources) are common problems faced by developing countries and restrain the use of MFA as a policy-making tool

The aim of this study is to apply MFA to analyze the cadmium flows through domestic activities to the environment The study areas are 3 communes (Co Loa – peri-urban area, Tho Xuan – rural area and Duong Lieu - craft village area Contents

of thesis include:

9 Description and understanding the activities related to cadmium flows

9 Qualification and quantification these flows

9 Recommendation of appropriate solutions for cadmium recovery

CHAPTER 1 – LITERATURE REVIEW 1.1 Overview of cadmium usage and environmental concerns

1.1.1 Sources and emissions

Cadmium is released to the biosphere from both natural and anthropogenic sources

1.1.1.1 Natural sources

Many substances, such as cadmium, occur naturally in the environment and

it is therefore important to distinguish between natural concentrations and flows of these substances and the extent to which these are increased by human activities

Volcanic activity is an important natural source of the release of cadmium to the atmosphere The annual global flux from this source has been estimated to be

820 tons (Nriagu, 1989) Deep-sea volcanism is also a source of the release of cadmium to the environment, but the role of this process in the global cadmium cycle still remains to be quantified Levels of up to 4.5 mg/kg have been found in volcanic soils (Korte, 1983)

Cadmium present in various types of rocks and soils is widely distributed in the earth's crust, in non-volcanic areas, at average concentrations ranging from 0.1

to 0.2 mg/kg of soil (GESAMP, 1984) This metal is commonly associated to zinc, and occurs naturally in zinc, lead and copper ores, which are the main deposits of cadmium These deposits can reach ground and surface waters, especially when in contact with soft, acidic waters

For naturally occurring substances the Background/Reference Concentrations (BRCs) are the range of concentrations that would be anticipated to

be present in the environment in the absence of any human activity Obviously, nowadays it is virtually impossible to present a definitive value for the background concentration of natural stable compounds, which can be transported by wind, water and biota

Table 1 summarizes available BRCs for cadmium in seawater, sediments and biota (mussel tissue)

• Refining of non-ferrous metals - residual levels of cadmium in zinc and lead ores; copper refining with the level of emissions is low

• Production of iron and steel - emissions to air, water and landfill may result from several of the input materials and processes for converting iron ore,

Table 1 Range in BRCs of Cd for fine-grained marine sediments, seawater and blue mussel within the OSPAR area (2002) a

coke and limestone/fluorspar to iron; production of refined steel from pig steel; or for secondary production of steel from scrap steel

• Combustion of fossil fuels - cadmium is a natural component of fossil fuels Electric power plants burning fossil fuels (coal and/or oil) release cadmium contained in the fuels which contain zinc sulphides As much as 190 ppm of cadmium occurs in mid-continental coals in the US Most cadmium will be captured in the fly ash and emission control devices; a small volume may be present in the slag/bottom ash which is landfilled or immobilized in cement

or asphalt-type processes

• Production/use of phosphate fertilizer - cadmium is contained in the phosphate fertilizers from the original rock phosphate Emissions may also occur through losses to water during the manufacturing process and disposal

of by-product gypsum to sea and disposal of gypsum to landfill Minor emissions may take place to air through dust created during manufacture

• Production of cement - cadmium is present as trace element in the raw materials of cement production Emissions may result from the feed system, kiln system, clinker-cooling and handling system Emissions to air as dust are likely, while direct emissions to water are not

Cadmium also enters the environment through the disposal of solid and liquid wastes, some of which will be associated with the production and use of cadmium-containing products (United Nations Environment Programme, 2008)

• Application of sewage sludge - to soil through application to land as fertilizer

• Incineration of domestic waste - cadmium is also released as a result of incinerating cadmium stabilized PVC and other products containing cadmium pigments or cadmium compounds found in commercial and household waste

• Leaching from landfill - cadmium concentration in leachates from controlled, state-of-the-art industrial or municipal landfills is often below the detection limit By way of example, in a case study in Denmark on a landfill containing industrial/municipal waste, demolition waste, 3% hazardous waste – no elevated cadmium was observed and the concentration was below detection

Table 2 shows the most significant sources of cadmium emissions in some European countries, taking into account overall use of cadmium

a : from Urszula Zielonka et al., 2009

Table 2 Cadmium and its compounds emissions to air, land, and water (2009) a

1.1.2 Fate, transport and transformation of cadmium in environment

1.1.2.1 Fate of cadmium in environment

Cadmium is a natural element in the earth's crust Pure cadmium is a soft, silver-white metal; however cadmium is not often found in the environment as a metal It is usually found as a mineral combined with other elements such as oxygen (cadmium oxide), chlorine (cadmium chloride), or sulfur (cadmium sulfate, cadmium sulfide) These compounds are solids that may dissolve in water but do not evaporate or disappear from the environment Physico-chemical properties and classification numbers of cadmium compounds were summarized in the WS Atkins Report (see table 3)

a : from Caspar Corden et al., 2000

Table 3 Main physico-chemical properties of Cd compounds (2000) a

1.1.2.2 Transport and transformation of cadmium in environment

Cadmium is released by various natural and anthropogenic sources to the atmosphere, aquatic environments (fresh and salt water environments) and terrestrial environments There are fluxes between these environmental components Cadmium released to the atmosphere can deposit to land and aquatic environments, and some cadmium emitted to soil over time will be washed out to the aquatic environments The long-term sinks are deep-sea sediments and, to a certain extent, controlled landfills, in cases where, owing to its physico-chemical properties, cadmium is immobilized and remains undisturbed by anthropogenic or natural activity (climatic and geological)

Cadmium, once released to air, is subject to atmospheric transport It is mainly emitted to the atmosphere in particle form The atmospheric transport of cadmium is governed by aerosol (particle) transport mechanisms: in the atmosphere, cadmium may be transported on local, national, regional or intercontinental scales, depending on various factors, including, for both natural and anthropogenic sources, particle size, the height of emission outlets and meteorology Because it has a relatively short residence time in the atmosphere (days or weeks), however, this metal is mainly transported over local, national or regional distances

Based on the relatively scarce specific evidence available, cadmium is considered to be subject to a certain degree of long-range air transport on an intercontinental scale Intercontinental transport is, however, expected to make only

a minor contribution to cadmium levels in regions affected by other, local emitting sources The regional and intercontinental atmospheric transport of cadmium contributes to deposition in remote regions, such as the Arctic, where there are few local sources for cadmium releases

There is no hemispheric transport modeling for cadmium As cadmium transport is governed by aerosol transport mechanisms similar to those governing the transport of lead (both are transported on aerosol particles with similar

properties), the transport of lead might be used as a rough surrogate of the potential intercontinental transport of cadmium Lead modeling is described in the United Nations Environment Programme review of scientific information on lead Taking into account the general similarities between the long-range atmospheric transport

of cadmium and lead and building on observations for lead, major contributions to Arctic cadmium pollution can be expected, as is the case with lead pollution, to come from sources located in Europe and in Siberia

With regard to aquatic systems, rivers transport cadmium and other heavy metals on a national and regional scale Ocean transport also occurs The oceanic residence time of cadmium has been estimated at about 15,000 years This indicates that cadmium may be accumulated and transported in significant amounts over long distances in the ocean It should be noted, however, that oceans have large natural reservoirs of cadmium The contribution of cadmium via rivers into the marine environment of the North Sea is in the same order of magnitude as the atmospheric deposition, which is the other main pathway of cadmium inputs in the region (United Nations Environment Programme, 2008)

1.1.3 Effect of cadmium on human health and environment

1.1.3.1 Human exposure pathways and effect of cadmium on human health

cadmium may be much higher leading to daily intakes of >100 mg (Järup et al.,

1998) Although cadmium use in stabilizers, pigments and plating will make a contribution to these figures, other sources may be more significant (United Nations

a : From OECD, 1994

Apart from the types of exposure outlined above, workers involved with the dealing and use of cadmium may be exposed to cadmium dust and/or fume The primary route for human uptake is via inhalation of workplace air For example, air concentrations in the workplace of the order of 10-50 mg/m3 would lead to a daily uptake of 25-125 mg (OECD, 1994)

WS Atkins,1998a provided details on workplace exposures at stabilizer and pigment preparation facilities, stabilizer mixing facilities and plating facilities Of those few facilities that provided information on air concentrations, it was found that the levels were consistent with those given above (i.e 10-50 mg/m3) - although those in plating facilities were much lower at around 1 mg/m3 Overall (although no data from plating facilities were supplied) it was found that cadmium levels in workers’ blood were less than 5 mg/l - a value to be compared with a typical value

of 1 mg/l among the general population (levels for smokers are about twice those

for non-smokers) (Caspar Corden et al., 2000)

• Human health effects

Cadmium is a non-essential and toxic element for humans The kidney is considered the critical target organ for toxicity of cadmium in humans The main critical influences include an increased excretion of proteins in urine as a result of proximal tubular cell damage The severity of the effect depends on duration and magnitude of exposure

Table 4 Cadmium intake for members of the public (1994)

Skeletal damage is another critical effect of chronic cadmium exposure at levels somewhat higher than those for which kidney proteinuria occurs Kidney proteinuria is an early effects indicator (United Nations Environment Programme, 2008)

The International Agency for Research on Cancer classifies cadmium in Group 1: carcinogenic to humans and the US Environmental Protection Agency has determined that cadmium is a probable human carcinogen by inhalation Epidemiological data from occupational settings confirm lungs being the primary target organ Cadmium is not considered a carcinogen by ingestion

Cadmium is mainly stored in the liver and kidneys Excretion is normally slow, and the biological half-life is very long (decades) in the muscles, kidneys, liver, and whole body Cadmium concentrations in most tissues increase with age

(Caspar Corden et al., 2000)

1.1.3.2 Effect of cadmium on environment

In the environment, some cadmium compounds are relatively water soluble, mobile in soil and bioavailability, depending on the water and soil chemistries It tends to bioaccumulation in organs such as the kidney and liver of vertebrates, but aquatic invertebrates and algae can also build up relatively high concentrations

In terrestrial ecosystems, soil micro-organisms and plants are more sensitive

to cadmium than soil invertebrates Both invertebrates and plants can accumulate cadmium Predators feeding on such soil invertebrates can give cadmium into the food chain, which suggests a risk of secondary poisoning through the food chain from worms to higher tropic levels (birds or mammals) The accumulation of cadmium by plants results in this contaminant entering the human food chain (United Nations Environment Programme, 2008)

Effects on birds and mammals are mainly due to kidney damage (dysfunction), and in sea birds and marine mammals in particular, cadmium

and micro-organisms are more sensitive to cadmium than soil fauna Inhibition of nitrogen-fixation in soil occurs at moderate cadmium pollution levels

In the aquatic environment, cadmium toxicity varies considerably even between rather closely related species, but overall the sensitivity decreases in the following order: invertebrates > fish and amphibians > primary producers (such as algae) Generally, cadmium toxicity decreases with increasing water hardness Reproduction processes and early life stages are the most sensitive

In aquatic systems, cadmium is most readily absorbed by organisms directly from the water in its free ionic form Cd (II) The acute toxicity of cadmium to aquatic organisms is related to the free ionic concentration of the metal Cadmium interacts with the calcium metabolism of animals In fish it causes lack of calcium (hypocalcaemia), probably by inhibiting calcium uptake from the water However, high calcium concentrations in the water protect fish from cadmium uptake by competing at uptake sites Effects of long-term exposure can include larval mortality and temporary reduction in growth Zinc increases the toxicity of cadmium to aquatic invertebrates Sub lethal effects have been reported on the growth and reproduction of aquatic invertebrates; there are structural effects on invertebrate gills (Nordic Council of Ministers, 2003)

1.2 Overview of MFA

MFA is a systematic assessment of the flows and stocks of materials within a system defined in space and time It connects the sources, the pathways, and the intermediate and final sinks of a material Because of the law of the conservation of matter, the results of an MFA can be controlled by a simple material balance comparing all inputs, stocks, and outputs of a process It is this special characteristic

of MFA that makes the method useful as a decision-support tool in resource management, waste management, and environmental management (Brunner and Rechberger, 2004)

1.2.1 Terminology used in MFA

1.2.1.1 Substance

In chemistry, a substance is defined as a single type of matter consisting of uniform units If the units are atoms, the substance is called an element, such as carbon (C), nitrogen (N), cadmium (Cd); if they are molecules, it is called a chemical compound, such as carbon dioxide or (CO2), ammonium (NH3) or cadmium chloride (CdCl2) (Agnès Montangero et al., 2005)

1.2.1.2 Goods

Goods are substances or mixtures of substances that have economic values assigned by markets In economic terms, the word goods are more largely defined to include immaterial goods such as energy (e.g., electricity), services, or information

In MFA terminology, however, the term goods stand for material goods only Nevertheless, the link between goods as defined by MFA and other goods as used

by economists can be important when MFA is applied, for example, for decisions regarding resource conservation (Brunner and Rechberger, 2004)

1.2.1.3 Process

A process is determined as a transport, transformation, or storage of materials The transport process can be a natural process, such as the movement of dissolved phosphorous in a river, or it can be man made, such as the flow of gas in a pipeline or waste collection The same applies to transformations (e.g., oxidation of carbon to carbon dioxide by natural forest fires vs man-made heating systems) and storages (e.g., natural sedimentation vs man-made landfill)

Processes are linked by flows (mass per time) or fluxes (mass per time and cross section) of materials Flows/fluxes across systems boundaries are called imports or exports Flows/fluxes of materials entering a process are named inputs, while those exiting are called outputs (Brunner and Rechberger, 2004)

1.2.1.4 Stocks

Stocks are determined as mass within the analyzed system, and they have the physical unit of kilograms A stock is part of a process comprising the mass that is stored within the process Stocks are necessary characteristics of a system’s metabolism For steady-state conditions (input equals output), the mean residence time of a material in the stock can be calculated by dividing the material mass in the stock by the material flow in or out of the stock Stocks can stay constant, or they can increase (accumulation of materials) or decrease (depletion of materials) in size (Brunner and Rechberger, 2004)

1.2.1.5 System and system boundaries

A system involves a set of material flows, stocks, and processes within a defined boundary The smallest possible system consists of just a single process Examples of common systems for investigations by MFA are: a region, a municipal incinerator, a private household, a factory, a farm, etc

The system boundary is defined in space and time It can consist of geographical borders (region) or virtual limits (e.g., private households, including processes relating the private household such as transportation, waste collection, and sewer system) When the system boundary in time is chosen, criteria such as objectives, data availability, appropriate balancing period, residence time of materials within stocks, and others have to be taken into account (Brunner and Rechberger, 2004)

1.2.1.6 Graphical representation

A process is represented by a box, flows by arrows, and the system boundary

by a dashed line

a : Agnès Montangero et al., 2005

1.2.2 MFA procedure

In general, an MFA starts with the definition of the problem and of adequate goals Then relevant substances and appropriate system boundaries, processes, and goods are selected Next, mass flows of goods and substance concentrations in these flows are assessed Substance flows and stocks are calculated, and uncertainties considered The following is steps of MFA:

• Step 1 Definition of problem and specific objectives

• Step 2 Selection of relevant substances, system boundaries, processes, and goods

• Step 3 Assessment of mass flows of goods

• Step 4 Assessment of substance concentrations in the goods

• Step 5 Calculation of substance flows

• Step 6 Consideration of uncertainties

• Step 7 Presentation of the results

• Step 8 Simulation of scenarios

The results are presented in an appropriate way to visualize conclusions and

to facilitate implementation of goal-oriented decisions It is important to note that these procedures must not be executed in a strictly consecutive way The procedures

Fig 1 Graphical representation of an MFA system a

have to be optimized iteratively The selections and provisions that are taken during the course of the MFA have to be continuously checked If necessary, they must be adapted to accommodate the objectives of the project

a : Agnès Montangero et al., 2005

In general, it is best to start with rough estimations and provisional data, and then to constantly refine and improve the system and data until the required certainty of data quality has been achieved (Brunner and Rechberger, 2004)

1.2.3 Application of MFA

• Industrial ecology: industrial ecology design principles related to MFA

Fig 2 MFA procedure a

9 Controlling pathways for materials use and industrial processes

9 Creating loop-closing industrial practices

9 Dematerializing industrial output

9 Systematizing patterns of energy use

9 Balancing industrial input and output to natural ecosystem capacity

• Environmental management and engineering

9 Environmental impact statements

9 Remediation of hazardous waste sites

9 Design of air pollution control strategies

9 Nutrient management in watersheds

9 Planning of soil-monitoring systems

9 Sewage sludge management

• Resource and waste management

9 Resource management: analysis, planning and allocation, exploitation, and upgrading of resources

9 MFA uses in waste management

- Modeling element compositions of wastes

- Evaluating material management performance in recycling/treatment facilities

9 Examples:

- Regional material balances

- Single material system analysis

• Human metabolism

9 Metabolism of the anthroposphere

9 Key processes and goods

- Input: water, food, building and transport materials

- Outputs: sewage, off-gas, solid waste

1.2.4 Some MFA case studies

1.2.4.1 Optimizing water and phosphorus management in the urban environmental sanitation system of Hanoi, Vietnam (Agnès Montagnero et al.,

2007)

Water, nutrient and energy management practices of the conventional sanitation system are unsustainable For example, large quantities of clean, potable water carry excreta through sewer systems Many areas in the world face clean water lacking problems The world’s drinking water resources decreased from 17,000 m3 capita-1 in 1950 to 7000 m3 capita-1 in the 1990s (UNDP, 1998) as a result of decreasing freshwater quantity and a near doubling of the world’s population (Berndtsson and Hyvonen, 2002) In addition, some 90% of the wastewater generated worldwide is discharged untreated into receiving water bodies (GTZ, 2006) Excessive nutrient loads in aquatic systems stimulate plant growth and reduce dissolved oxygen in the water (eutrophication) Moreover, valuable nutrients contained in human excreta are therefore lost Faeces and urine contain about 4.5 kg nitrogen, 0.55 kg phosphorus and 1.3 kg potassium per person and year This is theoretically sufficient to cover the annual wheat and maize demand of one person (Esrey, 1998) Since most of these nutrients are released with wastewater into the environment, artificial fertilizers must cover the agricultural nutrient requirement Production of artificial nitrogen fertilizer is energy-intensive and phosphate rocks are mined for the production of phosphorus fertilizers However, phosphorus reserves are likely to be depleted within 50-100 years (Cordell, 2005)

To secure water and phosphorus reserves for future generations, new environmental

sanitation concepts must be developed in compliance with the principles of “closed loop” resource management

Hanoi likes many other cities in developing countries with their high population growth, industrialization and economic development are facing increased resource consumption and environmental degradation Peri-urban agriculture plays important role in the supply of food and provision of income to the poorest section of the population However, rapid urbanization also creates pressure

on peri-urban land Farmers tend to use more fertilizers to enhance yield and benefit from their decreasing land area Improving balance between water and nutrient supply in urban waste products, and water and nutrient requirement in peri-urban food production could be the key to reducing resource consumption and environmental pollution

The material flow analysis method studies the resource fluxes used and transformed as they flow through a region Application of the developed material flow model proved to be appropriate to simulate the impact of selected measures on groundwater abstraction and phosphorus recovery in Hanoi’s province despite limited data availability Use of the model enables to identify the most determining parameters This not only enhances the design of effective measures, but also helps optimizing measurement programmes Moreover, Monte Carlo simulation allows to estimate variable uncertainty and, thus, to assess whether the impacts of different measures lie within the same range or if they differ significantly

Groundwater abstraction could be reduced by a third, if the water distribution system is improved, grey water is reused for toilet flushing and if water efficiency

of industrial processes is enhanced Despite the aforementioned measures, the groundwater withdrawal rate still exceeds the aquifer recharge rate Therefore, other strategies are essential, in particular, protection of surface water to facilitate its treatment for domestic use

By replacing septic tanks with urine diversion latrines, the percentage of phosphorus in waste products recovered for food production could be increased from 18 to 45% Furthermore, replacing livestock production by a higher production

of fish, vegetables, beans, soybean, and nuts could further raise recovery of phosphorus from 45 to 82%

This research describes the impact resulting from extreme scenarios to clearly reveal the impact of policy changes However, the model can be used to help

in evaluating scenarios developed jointly by different stakeholders Data provided

by the model can be combined with information on user’s needs and demands, user’s willingness to pay, costs, health impact, legal and institutional framework and, thus, contribute to the planning of sustainable environmental sanitation systems

1.2.4.2 Modeling cadmium flows in Australia on the basis of a substance flow analysis (Suphaphat Kwonpongsagoon et al., 2007)

The earth’s resources have been extracted, processed into products, utilized and disposed of continuously over many years It has long been known that these activities affect our environment in the form of the wastes and emissions that have subsequently proved harmful to humans and ecosystems In particular, potentially hazardous substances such as Hg, Pb and Cd have polluted the environment through such activities Therefore, they are considered as major problems in the specific field of hazardous waste treatment and management on various scales

As an example, cadmium is a widespread element occurring naturally at low levels in all soils, rocks, waters, plants and animals In Australia, as in many other parts of the world, the application of phosphate fertilizers to agricultural field and its atmospheric deposition are likely to cause main concern as regards Cd pollution

in the terrestrial environment (Alloway, 1995; Mclaughlin et al., 1996) In particular,

the soils of the north coast of Australia are naturally acid, with a pH of between 4 and 5.5, and are low in phosphorus due to extensive weathering (NSW Agriculture, 1995) As a result, much more phosphate fertilizer is added to achieve productive

yields in this area A relatively high concentration of Cd has been found in phosphate rocks, in the phosphoric acid used for the manufacture of fertilizers and

in some imported phosphate fertilizers At present, no feasible process is available

to eliminate Cd from phosphate rocks or phosphoric acid Furthermore, many parts

of Australia suffer from Stalinization due to irrigation as well as groundwater levels rising to the surface (ANZECC and ARMCANZ, 2000) Soil acidification is also a concern in many places A comparison of North America and Europe with Australia shows that whereas in North America many soils have a capacity to act as a sink for cadmium, a capacity claimed to be enhanced by the binding of Cd to other contaminants and organic matter in sludge and soil, huge areas of Australia have acidic and highly weathered soils Such soils act as sources of cadmium rather than sinks (Bureau of Rural Resources, 1988) Both Stalinization and acidification of soil can be a threat in terms of increasing Cd concentrations in agricultural products

(Mclaughlin et al., 1996)

In view of this situation, the Australian government has recently adopted a strategy to maintain safe levels of cadmium in agricultural soils and products (Mclaughlin, 2001)

The classical method of Material Flow Analysis or Substance Flow Analysis has been described in detail by Baccini and Brunner, 1991 and Brunner and Rechberger, 2004 The approach was developed and applied to regional aspects in the 1990s Cd flows in Australia have been studied on the basis of this classical approach in order to provide a holistic picture of the physical flows of Cd use and loss through Australia This allows all Cd inflows, outflows and stocks through each sub-compartment in the economy to be examined (Kwonpongsagoon, 2006)

The classical MFA was extended to the Mathematical Material Flow Analysis by Baccini and Bader, 1996 The Mathematical Material Flow Analysis combines the conventional MFA with modern concepts of mathematical modeling The concept is able to deal uncertainties of data and to simulate the behavior of the

system under various conditions, thus providing powerful tools to complement the conventional (steady state) approach of MFA/SFA In particular, the model is used

to understand the system, to identify the sensitive parameters, to investigate measuring and monitoring programs and to discuss possible measures This

approach has been applied in numerous studies in different fields: Zeltner et al., 1999; Real, 1998; Binder et al., 2001; Bader et al., 2003; Hug et al., 2004; Muller et

al., 2004; Van der Voet et al., 1995 and Schmid, 2005

As mentioned above, several Cd-related studies have already been carried out Most of them handle with problems of Cd in agricultural soils and produce, especially originating from phosphate fertilizers However, no study has yet been carried out on the overall Cd flows in Australia

In this research, a stationary model for evaluating the overall cadmium flows

in Australia is studied Its main objectives are:

1 To describe and understand the Cd flows by a mathematical model

2 To quantify the uncertainties and identify the key parameters of the system

3 To evaluate measures to reduce Cd flows to the environment

The calibrated model from a previous study (Kwonpongsagoon, 2006) was recalculated to improve the uncertainty This was achieved by applying sensitivity analysis together with an uncertainty ranking of the first-order parameters The important parameters of the model could be identified and better estimates for their uncertainties were achieved For the recalculated model, the parameters of concern were varied to simulate possible measures and options for reducing the flows to the various environmental compartments The most effective measures for agriculture area reduction of the Cd content in fertilizers and the atmospheric Cd deposition due

to emissions from urban areas and industries The stakeholders and policymakers involved in environmental management can benefit from such models by simulating possible future developments

1.2.4.3 A Material Flow Analysis of phosphorus in Japan - The Iron and Steel

industry as a major phosphorus source, (Kazuyo Matsubae-Yokoyama et al.,

2009)

Phosphorus is present only as a trace element on the Earth but is one of the

important resources for agricultural production and for the chemical industry, where

it used in fire retardants, glues, food additives, detergents, and so on Natural

phosphate ore (phosphate rock) is traded worldwide, mainly as a raw material for

a : from U.S Geological Survey, 2007

In the case of Japan, all phosphate ore is imported from China, South Africa,

Morocco, Jordan etc The total amount of phosphate ore imported into Japan is

reducing year by year (from approximately 14.0 × 102 kt in 1993 to 8.5 × 102 kt in

2002) (Ministry of Finance, 2004) Due to growing world demand for fertilizers,

deposits of high-grade phosphate ore could be exhausted within the next 100 years

(Abelson, 1999; Christen, 2007), and the average price of the ore in 2002 was

approximately 1.5 times that in 1993 Furthermore, we faced an extraordinary price

increase of P ore and its derived fertilizer in 2008 Since 2007, in terms of the rising

production costs and strong demands, the price of phosphate fertilizer has raised

sharply Meanwhile, the price of phosphorus ore and phosphorus chemical products

also increased In order to maintain a sustainable supply of phosphorus to meet

Table 5 Amount of phosphate ore was mined in some countries during 2005 a

domestic demand, new sources of phosphorus need to be developed Sewage sludge

is one alternative as a potential source of phosphorus, and some research workers are attempting to develop new technologies for recovering phosphorus from it (Christen, 2007)

Coal and iron ore are necessary raw materials for the production of iron and steel, and they contain very small amounts of phosphorus Because phosphorus has detrimental effects on the mechanical properties of steel, it is removed from molten iron in the steelmaking process by slag treatment A flux based on calcium and iron oxides (CaO–FetO) is needed to or injected into liquid pig iron (hot metal) or molten steel (FetO is a nonstoichiometric oxide formed with the oxidation of iron at high temperature), and the phosphorus in the molten metal is removed in the slag phase as phosphate ion, according to the oxidation reaction

Where, (O2−) and (PO4)3− denote free oxygen ion and phosphate anion in the slag, respectively Because phosphate anion is well stabilized by calcium oxide (CaO) in the slag in the form of calcium phosphate, phosphorus can be efficiently removed from liquid iron to give a slag of high basicity That is, one of the most important roles of steelmaking slag is dephosphorization of molten steel, and the slag after the dephosphorization contains approximately 2-10% mass of phosphorus pentoxide (P2O5), together with FetO, CaO, and silica (SiO2) As a result, steelmaking slag is unavoidably generated as a by-product in the steelmaking industries Some steelmaking slag is used as a road-construction material, but most

is merely a waste product that has to be disposed of Therefore, steelmaking engineers and researchers are investigating new technologies for reducing the amount of steelmaking slag that is generated, and they are examining ways to develop new demand for the remaining slag as a valuable resource from the environmental and economic viewpoints In short, although phosphorus is a very

important and strategic resource, it is a barrier to the production of high-quality steel products

Although Smil, 2000 performed a detailed study of natural reservoirs of phosphorus and its flow, the author did not take into consideration the phosphorus flow associated with iron and steel production A significant amount of phosphorus goes through the steel industry and is accumulated in steelmaking slag and not used

as a phosphorus resource

A new process for recovering calcium phosphate from steelmaking slag is based on the precipitation of various separate crystalline phases in the slag during cooling and the differences in the magnetic properties of these phases The basic principle of this process and the results of some trials made by using practical steelmaking slags are introduced in this article

This article presents the phosphorus flow on the basis of secondary data, new technology for phosphorus recovery from steelmaking slag, the total substance flow

of phosphorus in Japan, and the results of an environmental assessment of phosphorus recovery

Some conclusions from research: First, investigating domestic phosphorus material flows in Japan, including the iron and steel industry, based on statistical data in 2002 to determine potential phosphorus resources that are currently untapped A major finding was that the quantity of phosphorus in iron and steelmaking slag is almost equivalent to that in imported phosphate ore, both in terms of the amount and the concentration Second, assessing the amount of phosphorus that could be recovered from steelmaking slag by the application of a strong magnetic field By means of a waste input–output analysis and a study of total materials requirements, the recovery of phosphorus by this new process would have considerable environmental and economic benefits Christen, 2007 mentioned the main problem lies in the economic situation and cost of recovering phosphorus: the world market price for phosphorus is still below the current cost of its recovery

However, the recovery cost could decrease through introduction of a commercialized process

1.2.4.4 Substance Flow Analysis of Mercury Intentionally Used in Products in the United States (Alexis Cain et al., 2007)

Exposure of fish to methylmercury can harm the health of both humans and wildlife In the United States, mercury (Hg) enters water, and ultimately fish, primarily as a result of atmospheric deposition Atmospheric deposition occurs as a result both of U.S anthropogenic emissions of more than 100 tonnes annually and of emissions from over-seas sources and natural sources Discharges directly through water are a small percentage of mercury inputs to most water bodies; an estimated 46 tonnes is discharged to water annually, the bulk of which occurs as a result of mining activities in a relatively small number of watersheds Landfills also receive significant amounts of mercury, estimated at

approximately 2.700 tonnes annually (Rackley et al., 2004) A small percentage of

landfilled mercury can become bioavailable if it escapes the landfill in leachate or volatilizes to the air (USEPA, 1997) Also, future changes in landfill design and operation such as the development of bioreactors could change the fate of mercury disposed of in landfills

Past and current human activities are considered responsible for approximately two-thirds of the mercury in the global atmosphere, with the remaining mercury releases caused by natural processes, such as volcanic activity and weathering of rock (Shannon and Voldner, 1995; Engstrom and Swain, 1997;

Seigneur et al., 2004) Anthropogenic releases of mercury can be divided between

releases that result from deliberate use of mercury and those that result from the use

or processing of raw materials, such as coal, gold ores, or limestone, that contain trace amounts of mercury Releases resulting from deliberate mercury use can be further divided between those resulting from the use of mercury in production processes, such as the mercury cell process for the manufac-ture of chlorine and

caustic soda and, in devel-oping countries, the processing of gold ores with mercury and the use of mercury in products This article addresses only mercury releases caused by the deliberate use of mercury in products

Mercury has been used in numerous products because of its many valuable properties For example, it conducts electricity, amalgamates with other metals, and expands and contracts evenly with changes in temperature or pressure U.S mercury use, in both products and processes, peaked between 1963 and 1969, at an average of 2.600 tonnes per year Use declined to 2.000 tonnes per year in the 1970s and 1.700 tonnes per year in the 1980s More rapid decreases began in the early 1990s, when the use of mercury in most types of batteries was phased out and the use of mercuric fungicides in paint was terminated As a result of these past uses, a significant mass of mercury has built up in U.S industry; the USGS estimates that

in 1996, 3.750 tonnes of mercury were contained in U.S product stocks, in addition

to 3.050 tonnes in chloralkali plants By 1997, the most recent year in which industrial use data were compiled by the USGS, mercury use had declined to 350 tonnes (Sznopek and Goonan, 1997)

State and local governments and, to a lesser extent, the U.S federal government expend sig-nificant effort in attempting to reduce the environmental impact of mercury in products through legislation, regulation, and voluntary programs (QuicksilverCaucus, 2005) These efforts attempt both to reduce the mercury content of products and to better manage mercury containing wastes But the impact of these efforts on environmen-tal releases of mercury is uncertain, because governments lack detailed information about mercury releases from various types of product and about the likely consequences of various options for managing mercury wastes or for influencing mercury use in products This article uses substance flow analysis to help generate preliminary estimates of mercury releases

to meet these information needs

Barr Engineering Company, supported by the U.S Environmental Protection Agency and building on previous similar efforts for the states of Minnesota and Wisconsin, conducted a study to quantify national mercury releases for the U.S from the major categories of mercury containing products, accounting for the bulk

of mercury releases caused by products We did not evaluate some Hg containing products that may be important sources of direct mercury exposure, such as some medicines, skin lightening creams, vaccines (Counter and Buchanan, 2005), and laboratory chemicals that contain mercury compounds, nor did we evaluate releases

from the use of mercury in religious rituals and folk medicines (Riley et al., 2001)

The model generates quantitative estimates for mercury releases to air, water, and land for 1990, 2000, and 2005, attempting to account for release throughout the product’s life cycle, including product manufacture, distribution, use, and disposal This approach results in an improved estimate of mercury releases and shows that mercury containing products result in significant releases of mercury to the environment This approach can also be used to estimate the likely impacts of options that would decrease mercury use or improve management of mercury containing wastes

Modeling the flow of mercury in products and their subsequent use and disposal leads to improved estimates of mercury releases associated with those products Use of substance flow analysis shows that U.S mercury releases from mercury containing products declined dramatically between 1990 and 2005, but that they continue to be a significant source ofmercury releases to the environment on a national basis Moreover, applying substance flow analysis to mercury in products provides us with new insights about where mercury releases might be occurring and shows the importance of the iron and steel recycling system as a potentially significant source of mercury releases to air Moreover, this model can be used as a predictive tool to evaluate the potential impact of measures to reduce the use of mercury, to improve the management of mercury wastes, or to reduce mercury releases through the installation of mercury control technologies

CHAPTER 2 – APPROACH AND METHODOLOGY

2.1 Description of study area and scope

2.1.1 Co Loa commune

™ Location

Co Loa belongs to South-East of Dong Anh suburban district The North is near Uy No and Viet Hung commune, the East is near Duc Tu commune, the West

is near Xuan Canh and Vinh Ngoc

commune and the South is near Mai

Lam and Dong Hoi commune (see

Fig 3)

™ Land use

Total natural land area:

806.9 ha Agricultural land: 454.25

ha (land for paddy: 438.22 ha, land

for aquaculture: 36.58 ha), non

agricultural land: 316.07 ha and

land for other goals: 138.75 ha

(Source: Annual report of Co Loa