Investigation on a combination of chemical and biological methods for the treatment of pulp and paper mill wastewater in vientiane

For the wastewater sample 2 taken from tissues paper factory in Vientiane, the coagulation and follwing by biological treatment with activated sludge are suitable methods.. In some count

PAPER MILL WASTEWATER IN VIENTIANE

Major: Waste Management and Contaminated Site Treatment

MASTER THESIS

SUPERVISOR: ASSOC PROF DR BUI DUY CAM

ASSOC PROF DR DO QUANG TRUNG

Hanoi, November 2011

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Table of contents

Abbreviations iv

List of tables v

List of figures vi

Abstracts vii

Acknowledgement viii

Introduction 1

CHAPTER I LITERATURE STUDY 2

1.1.Status of environmental management in Vientiane 2

1.1.1 Introduction of Vientiane 2

1.1.2 Environmental issues in Vientiane 3

1.1.3 Situation of pulp and paper mill in Vientiane 7

1.2 The pulp and paper mill wastewater treatment technologies 11

1.2.1 Pulp and paper mill production 11

1.2.2 Sources of pollution in the production of pulp and paper mill 12

1.3 Some methods commonly using to treat with the wastewater 15

1.3.1 Physicochemical treatment 15

1.3.2 Membrane filtration 19

1.3.3 Biological treatment 21

CHAPTER II EXPERIMENT 25

2.1 Research objective 25

2.2 Equipment and Chemicals……… ……… 26

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2.2.1 Equipments 26

2.2.2 Chemicals 26

2.3 Analitycal methods in the study 28

2.3.1 Determination of Chemical Oxygen Demand 28

2.3.2 Determination of Biochemical Oxygen Demand……… …29

2.3.3 Analysis of Ammonia content 30

2.3.4 Analysis of Nitrite and Nitrate 31

2.3.5 Procedure for the determination of Phosphate 33

2.4 Preparation of Pulp and paper mill samples 34

2.5 Physicochemical method for the pretreatment of pulp and paper mill wastewater……… 35

2.5.1 Coagulation experiments for sample 1 and 2 35

2.5.2 Reduce of COD value by pH change for sample 3 35

2.6 Removal of COD in pulp and paper mill wastewater by combinated Aerobic and Anaerobic circulatory System ……….35

2.7 Material filling in column 36

CHAPTER III RESULTS AND DISCUSSION 39

3.1 Pretreatment of pulp and paper mill wastewater by physicochemical methods39 3.1.1 Coagulation experiments for sample 1 and 2 39

3.1.2 Effect of the pH and PAC doseage to the reduction of COD in sample 3 41

3.2 Investigation of the biological treatment with activated sludge 43

3.2.1 Effect of retention time on COD removal for sample 1 43

3.2.2 Effect of retention time on COD removal for sample 2……… 44

3.2.3 Effect of retention time on COD removal for sample 3 ………….……….45

3.3 Primary investigation on the treatment of pulp and paper mill wastewater by the combination of circulatory aerobic and anaerobic system 46

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3.3.1 The reduction of COD 47

3.3.2 The change of Ammonia 48

3.3.3 The change of Nitrite 49

3.3.4 The change of Nitrate……… 50

3.3.5 The change of Phosphrus 51

3.3.6 A proposed model for pulp and paper mill wastewater treatment for Vientaine factories 52

Conclusions 54

References ……….55

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Abbreviations

AC Anaerobic Contact process

AF Anaerobic Filter

AOX Adsorbable organic halogens

BOD Biological Oxygen Demand

COD Chemical Oxygen Demand

CSOCA&A Circulatory system of combination of Aerobic and Anaerobic

DO Dissolved Oxygen

MLSS Mixed Liquor Suspended Solids

PAC Poly Aluminum Chloride

TSS Total suspended solids

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List of tables

Table 1 Wastewater Quality in Vientiane Capital Jan-Dec 2000[2]………… …5

Table 2 Industrial Growth in Lao PDR [2]……… ……6

Table 3.Pollutants in the wastewater in the factory’s ponds[8]……… 8

Table 4 Typical efficiencies of aerobic systems [9]……… 22

Table 5 Anaerobic degradability of pulp and paper mill wastewater[19]… … 23

Table 6 Data of standard curve 30

Table 7 Data of ammonia standard curve……….32

Table 8 Data of nitrite standard curve making……… 33

Table 9 Data of nitrate standard curve……… …34

Table 10 Data of phosphorus standard curve……… 35

Table 11 Effect of PAC dosage to COD reduction for sample 1……….….41

Table 12 Effection of coagulant PAC to COD removal ……… …42

Table 13 Effection of pH changed to COD removal………44

Table 14 Effection of coagulant PAC to COD removal ……… 44

Table 15 Data of effection of aerobic to COD removal ……… 46

Table 16 Data of effection of aerobic to COD removal………47

Table 17 Data of effection of aerobic to COD removal………48

Table 18 Data of effection of CSOCA&A to COD removal……….49

Table 19 Data of effection of CSOCA&A to NH4+ due to times……… 51

Table 20 Data of effection of CSOCA&A to NO22- due to times……… 51

Table 21 Data of effection of CSOCA&A to Nitrate due to times………52

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Table 22 Data of effection of CSOCA&A to Phosphorus due to times……… 53

List of figures Figure 1 Map of Lao PDR……… ….2

Figure2 Source flowchart from the production line in KPS paper mill in

Laos [8]……….……… 10

Figure 3 Process description for pulp and paper mill factory[10]………….… 12

Figure 4 Pollutants from various sources of pulping and papermaking [11]……….….15

Figure 5 Diagram of Flocculate w11……… 27

Figure 6 Diagram of Aerobic system W11………27

Fignure 7 COD standard curve 30

Figure 8 Ammonia standard curve……….……… 32

Figure 9 Nitrite standard curve……… …33

Figure 10 Nitrate standard curve……….…… 34

Figure 11 Phosphorus standard curve……….……….…….35

Figure12 Diagram of combining Anaerobic and Aerobic system………… … 38

Figure 13 : Surface of porous material……… 39

Figure14 Microorganism layer……… …38

Figure 15 Membrane of porous material after three times circularly pumping water containing nutrient……… 38

Figure 16 Diagram of effection of PAC dosage to COD removal………… …38

Figure 17 Diagram of effection of coagulant PAC to COD removal……….41

Figure 18 Diagram of effection of pH changed to COD removal… 42

Figure 19 Diagram of effection of coagulant PAC to COD removal………… 43

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Figure 20 Diagram of effection of aerobic to COD removal……….… … 44

Figure 21 Diagram of effection of aerobic to COD removal……….……45

Figure 22 Diagram of effection of aerobic to COD removal……….……46

Figure 23 Diagram of effection of aerobic to COD……… …48

Figure 24 Diagram of effection of aerobic to Ammonia……….…… 49

Figure 25 Diagram of effection of aerobic to Nitrite……… 50

Figure 26 Diagram of effection of aerobic to Nitrate………51

Figure 27 Diagram of effection of aerobic to Phosphrus……… …51

Figure 28 : A purposed model wastewater treatment process using activated sludge……….…… 54

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Abstract

Lao PDR is a country rich in natural resources and its water resources are vital in providing the basic needs for its people, socio-economic development of the country The scale and extent of environment problems in the urban areas of Vientiane is relatively small compared to other cities in the region due to its relatively small size and population, low population density, and relatively low level of industrial activity However, there are some water pollution problems in major urban areas caused by various water uses by communities (households, hotels, hospitals and entertainment centers) In addition, the actions of the agricultural and industrial sectors have resulted in water pollution, including mineral exploitation, pulp and paper mills factories and hydropower generation Therefore, in accordance with the Millennium Development Goals, the government set targets in order to improve the local people’s access to safe drinking water by the years 2015 For in Vientiane is one looking for manage methods for treatment wastewater discharges

In this study, the situation of environmental pollution in Vientiane in general and from the pulp and paper mill wastewater in particularly was evaluated These are recognized that the environmental issues in Vientiane having problem The wastewater samples were collected from pulp and paper mill factories in Laos and Vietnam for the experiments in laboratory of Environmental Chemistry, Hanoi University of Science The physicochemical and biological methods for the treatment of wastewater were investigated The results shown that, the pulp and paper mill wastewater can be pretreated by the reduction of pH with dilute H2SO4 acid at pH = 3; and by the coagulation with poly aluminum chloride (PAC) The COD removal from 74.21% of sample 1 and 62.16% of sample 3 Then the wastewater samples can be treated by using combined aerobic and anaerobic system with efficiency of COD removal 94.99% of anaerobic and 90% for aerobic

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alone the reduction of the COD For the wastewater sample 2 (taken from tissues paper factory in Vientiane), the coagulation and follwing by biological treatment with activated sludge are suitable methods

Acknowledgement

The time of doing thesis in HUS is very special to me It is the time for to harvest my knowledge and to meet interesting Vietnamese friends Thank you for accepting the long hours, weekends and holidays I have spent working, for taking good care of me during this time and for pushing just hard enough to make sure I finally completed my thesis

I would like to express my utmost appreciation and thanks to Prof Dr Bui Duy Cam and Assoc Prof Dr Do Quang Trung for them valuable guidance, endurance, encouragement and support throughout this research

Several people have given me assistance with the work in this thesis I thank Mr Mai Xuan Thang and the late Mrs Hoang Thu Trang for assistance in the laboratory, and for assistance with the experimental set up

Special thanks are extending to Prof Bernd Bilitewski, Prof Nguyen Thi Diem Trang for your role in this circumstance

Finally, the generous financial support by the DAAD Also the support of the Hanoi University of Science and Dresden University of Technology is acknowledged

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Introduction

Water are vital element for both of demand’s people and socio-economic

development of the country As the population has grown, demand is also incresed and has had to travel further in search of good quality water, marginal and polluted sources have started being tapped Therefore, investigation of the water quality in Vientaine is very important because Laos is one of developing country looking for the suitable system for wastewater treatment

The amount and characteristics of the pulp and paper mill wastewater depend highly on raw materials and processing conditions The pulp and paper mill wastewater may cause oxygen deficiency, acute or chronic toxicity, mutagenicity in recipient water bodies In some countries the discharge standands for pulp and paper mills include

conventional biochemical oxygen demand (BOD), chemical oxygen demand (COD) and suspended solide also nutrients and organochlorine compounds expressed as adsorbable organic halide (AOX) There are number of technique to reduce the discharged pulp and paper mill wastewater The mechanical treatment method with primary clarifies is usually applied to remove the wastewater solids and the organic load while dissolved organics are removed in aerated lagoons and/or activated sludge system, the most commonly applied biological processes However, these processes are expensive and none is

consider to be economically viable when this is done as standard process Biological method have been found to be more effective and eco-friendly since they are capable of degrading not only lignin but also chloro-oganics contributing to AOX

In my study, the overview of the wastewater treatment technologies for pulp and paper mill factories are conducted for the purpose of applying to Laos and both methods

of chemical and biological ones are investigated for the treatment of pulp and paper mill wastewater in Vientiane The real samples from Laos, Vietnam pulp and paper mill wastewater have been tested

CHAPTER I LITERATURE STUDY 1.1 Status of environmental management in Vientiane

1.1.1 Introduction of Vientiane

The Lao People’s Democratic Republic (Lao PDR) is near to Myanmar,

Cambodia, the People’s Republic of China , Thailand, and Viet Nam The total land area

of the country is 236,800 square kilometers (km2) with a largely mountainous

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topography The capital, Vientiane (See picture 1 - Map of Lao PDR), however lies on a plain The country is bordered on the west by the Mekong River, making the river an important artery for transportation, communications, and trade with other countries sharing tributaries of the Mekong River

Set in the heart of Vientiane, Laos from the north latitude 17 45'50 - 22'38 18 09'37 5'40 and 102 - 103 east longitude and the natural area 3.920 km2 Vientiane is the 9 District: Chanthabuly, Sikottabong, Xaysettha, Sisattanak, Naxaythong, Saythany,

Hatsaiphong, Saengthong Phakngum area and population density level of economic development of each district is different Entire Vientiane has 500 villages, of which urban area accounts for 76% of villages, rural areas account for only 24% Population Vientiane has highest level of culture, a spirit of hard-working, patriotic tradition and unyielding will to revolution [1]

Figure 1 Map of Lao PDR

Lao PDR is a rich country in natural resources and its water resources are vital in providing the basic needs for its people, for socio-economic development of the country and for the ecological systems The availability of water resources has created favourable conditions for the Laos and for the socio-economic development of the country, but it is essential that the country protects and manages water and water resources in a sustainable way Despite this a scarcity of water for both drinking and irrigation purposes is common

in some provinces particularly in remote areas As the population has grown, and has had

to travel further in search of good quality water, marginal and polluted sources have started being tapped The major surface water resources are from rivers, streams and via

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gravity fed systems and through the protection of spring water Groundwater is sourced from boreholes with hand pumps and from protected dug wells Rainwater is also

harvested in reservoirs or tanks and individual collection jars [2]

1.1.2 Environmental issues in Vientiane

The scale and extent of environment problems in the urban areas of Vientiane is relatively small compared to other cities in the region due to its relatively small size and population, low population density, and relatively low level of industrial activity

However, despite recent investments, there remain few systems in place to ensure that all, and in particular the poor, benefit from environmental improvements and environmental problems can be controlled in the future (EPL, 1999)

The Water Quality Laboratory of the Ministry of Agriculture and Forestry

reported that the quality of water in Lao PDR has generally been good according to the past 15 years of monitoring data However, there are some water pollution problems in major urban areas caused by various water used by communities (households, hotels, hospitals and entertainment centers) In addition, the actions of the agricultural and industrial sectors have resulted in water pollution, including mineral exploitation and hydropower generation The degradation of water bodies and catchments due to

sedimentation, land erosion and drying out continues [3],[4]

Poverty and Access to Clean Water and Sanitation throughout Lao PDR, there is

a high incidence of diarrhea and dysentery caused in part by inadequate water supply, poor sanitation and sewerage, and absence of wastewater treatment facilities With rising populations in urban and upland areas, water pollution is getting worse Also the poorest districts have less than half the national average of daily water use, due to less access to water for either personal use or irrigation purposes For this reason, various challenges exist in the field of water quality monitoring, modeling and other technical strengthening; however, there is a need for a more systematic approach Currently, some ministries and departments are responsible for water resources independently carry out water quality management, such as water quality monitoring and analysis The Water Resources and Environment Administration (WREA) needs to play an active and leading role in water quality management in line with its mandate on water resources and environment Also, stronger water quality policies and strategies are needed to deal with the rapid

development of water resources and possible impacts on water quality and ecosystems

The updating of the National Water Resources Policy and Strategy and the

possible review of the Law on Water and Water Resources will provide the opportunity for this policy and strategy development Reviewing and setting coordinated water

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quality monitoring standards and procedures need to be considered Furthermore,

capacity and systematic coordination procedures and mechanisms among agencies

responsible for overall and sectored water quality monitoring and management need to be built [4]

Environmental measures used in solid waste management in Vientiane, including market and non-market instruments as well as public education and training programmers (moral suasion) Under pressure from rapid demographic growth, socio-economic

development and urbanization, however, water quality is deteriorating In urban areas, pollutants from roads, commercial and industrial areas, and private properties wash into drains and watercourses Litter, dust and dirt, oil and grease, particles of rubber

compounds from tires, particles of metal, glass and plastic from vehicles, and lead are common pollutants Residential properties and open spaces contribute sediments and nutrients [5] Urban drains also act as secondary sewers carrying industrial discharges, septic tank seepage and overflows in wet weather It is common practice to dispose of sewage to surface drains and drainage channels As a result, wastewater is invariably contaminated with faecal matter from latrines and coli-form septic tank effluent

Wastewater monitoring was conducted in Vientiane in 2002 Samples were collected from 15 monitoring stations Parameters were measured: pH, conductivity, alkalinity, BOD5, COD and temperature The monitoring results showed that the average of all parameters were within acceptable limits, although certain samples exceeded standards for Class A wastewater discharge, issued by the Government in 1994 [2]

Table 1 Wastewater Quality in Vientiane Capital Jan-Dec 2000 [2]

Parameters Unit Range of Avg Results Standard

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1993, the institutional framework has been established and followed up by a place of legal framework for instances: Environmental law, land law, forestry law, water and water resources law, and others [3] However, the growing number of industries has increased the risk of pollution The larger mills and industries of concern in Lao PDR are pulp and paper, timber, food processing and garment manufacturing Most of these have only limited wastewater treatment systems for reducing waste concentrations and loads in the final effluents to waterways Likewise, the increasingly large number of smaller industries also produces an increasing risk of pollution There has been an increase in the output of in the industrial sector from 8 percent of GDP in 1999 to 11.3 percent in 2003 The total number of industries has grown nearly four-fold from 1994 to 2003 (Table 2) Therefore, in accordance with the Millennium Development Goals, the government set targets in oder to improve the local people’s access to safe drinking water by the years

2015

Table 2 Industrial Growth in Lao PDR [2]

Large(>100 employees)

Medium(10-100 employees)

Small(<10 employees)

management of natural resources, specifically water Moreover, the Environment

Protection Law (EPL), the Water and Water Resources Law and the regulation on

wastewater discharge forbid any water pollution and propose that the personal sector be responsible for the environmental damage and the related social and economic effects that result from their industrial activities, specifically from wastewater and air emissions

Finally, in according by the presentment of the Minister of Industry and

Commerce, in 2005 has regulation issued of the main condition on the industrial factories [7] are follows :

a) To prohibit discharging directly or indirectly into public water that may have adverse impacts on ecology of water body, health of people or use of water, b) To require getting approval on wastewater treatment system before starting construction of factories from Director of Industry Department of the Ministry or Province as well as submit a treatment approach, waste management system plan c) To rein stalling wastewater treatment system, volume measurement equipment, and other necessary facilities for monitoring, and sample analysis,

d) To require frequently monitoring monitoring and analyzing the wastewater, and report the analysis results to Director of Industry Department of the Ministry or Province,

e) To require recording the daily use of chemical substances and explaining the purpose of their use

1.1.3 Situation of pulp and paper mill in Vientiane

There are six pulp and paper mills in which five factory located in Vientiane Capital City and one in Vientiane Province For pulp and paper mills factories were processed as to less than 200 tones of output per day, and small scale have to compared with in near countries KPS Paper mill is one factory in Vientiane Capital, this is factory using water from stored in three underground buffer tanks and from supply water to the manufacture process The raw material processed is bamboo, which is reduced to chips

by a cutter For delignification, the chips are immersed in a sequence of five tanks

containing caustic soda, an alkaline solution Sulfur is also added After concentration, the chips are removed manually and placed in a grinder The pulp produced in the grinder station is mixed with recycled paper (which includes rejected and surplus paper) in a water tank The flow chart of the production line is shown in figure 2 After screening, the mixture is transferred into the paper-making machines The finished paper is then

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colored, cut and stamped before being packed for export The plant uses sodium

carbonate (Na2CO3) or sodium hydroxide (NaOH) (or cold soda) mixed with sulfur (S) amount 1,688 tones/year to deepen of the paper it manufactures and exports In the factory is general discharged effluent water amount 600 m3/day

Wastewater discharges from the factory has not installed any effluent treatment system even though it is pre-determined in the factory’s project document Therefore, the wastewater from the factory are two types of first black wastewater from the

delignification stage of the pulping process, and second white wastewater from the paper making process The black wastewater is discharged directly addicted to the local steam and a series of ponds in the factory through two separated pipeline systems according [8]

is shown in table1

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Table 3.Pollutants in the wastewater in the factory’s ponds [8]

wastewater discharged

Black wastewater discharged

Maximum allowed (industrial wastewater Discharge regulation 326/MIH )

Bamboo surplue Dust Chipping

Delignification

Pulping Process

Black wastewater

Solid waste

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Figure 2 Source flowchart from the production line in KPS paper mill in Laos [8]

1.2 The pulp and paper mill wastewater treatment technologies

1.2.1 Pulp and paper mill production

The characteristics of the wastewater generated from various processes of the pulp and paper industry depend upon the type of process, type of the wood materials, process technology applied, management practices, internal recirculation of the effluent for recovery, and the amount of water to be used in the particular process

That the load of chlorinated phenols and acids in the wastewaters of hardwood kraft mill was three to eight times lower than it was in the soft wood kraft mill The pulping and paper making process is prominent compound in the produce pollutants at various stages The wastewater pollution load from individual pulping and papermaking process There have

1 Mechanical forces in the presence of water (mechanical pulping) The process involves passing a block of wood, usually debarked, through a rotating grindstone where the fires are stripped of and suspended in water

2 Chemical pulping which utilizes significantly large amounts of chemicals to break down the wood in the presence of heat and pressure The spent liquor is then either recycled or disposed of by burning for heat recovery

3 A combination of the two (chemical thermo-mechanical pulping) The wood is first partially softened by chemicals and the remainder of the pulping proceeds with

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mechanical force According by G Thompson, J Swain, M Kay, C.F Forster [10] in conventional mechanical pulping, the dissolved organic material from the wood is split between the pulp passing onto the paper machine and that going to waste The

preponderance of the pollutants which go forward to the paper machine will subsequently exist released in the paper machine wastewater, except where the process is operated in a closed loop system In difference, chemical pulping plants, with recovery systems in place, find that most of the organic pollutants dissolved during pulping are retained in the recovered liquors which are generally incinerated The highest wastewater losses are found in mills which operate chemi-mechanical process However, the wood pulping and production of the paper products generate a considerable amount of pollutants

characterized by biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids (SS), toxicity, and color when untreated or poorly treated effluents are discharged to receiving water Pulp and paper mills generate varieties of pollutants depending upon the type of the pulping process This is made from cellulose fibers, carbohydrates as sugar and lignin, and is adhesive substance for the cellulose fibers The current environmental limitations have caused the decrease of the consumption of the natural resources for this industrial use So, in this industry the recycling of fibrous raw materials and/or alternative is the high water usage, between 20,000 and 60,000 gallons/t

of products, results in large amounts of wastewater generation [11, [12] For the water utilization dependents on the technology and the product obtained were 3-8 m3/t Carton

of product, 10-15 m3/t Newspaper of product, 15-20 m3/t Paper tissue of product, and Writing paper 10- 20 m3/t of product [13] The wastewater from the papermaking and de-inking process differs from the pulping process due to there being no breakdown of raw material, other than the discards of cleaning and screening Foremost sources of pollutant releases in pulp and paper manufacture in figure 3 Process description for pulp and paper mill factory it show below:

Figure 3 Process description for pulp and paper mill factory [10]

1.2.2 Sources of pollution in the production of pulp and paper mil

Mechanical

pulping

Chemical pulping

Chemo-mechanical pulping (CMP)

Thermo-mechanical pulping (TMP) Papermaking

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The pulp and paper industry possessions (wood, water) and fossil fuels, electricity and a significant contributor of pollution discharges to the emissions from pulp and paper mills to air, water and land gives a serious impact on environment quality that ultimately affects the health of both human and ecosystems However, the recovery and reuse of water can increase the concentration of organic and inorganic species, which in turn can affect paper formation, increase bacterial loading or lead to corrosion and odours

According by D Pokhrel, T.Viraraghavan [10] in boring the wood pulping and

production of the paper products cause a significant quantity of pollutants characterized

by biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids (SS), toxicity, and color as untreated effluents are discharged to receiving water

The concentration of total wood extractives in the different fractions of the

influent and effluent from the activated sludge plant 88% of the wood extractives were removed in the activated sludge process In the determination of wood extractives the normal procedure is to remove larger particles by centrifugation before extraction in order to obtain reproducible results for dissolved and colloidal substances [11] However, integrated Kraft pulp and paper mill wastewater was characterized before (influent) and after (effluent) the activated sludge process by micro-filtration and ultra-filtration into different size fractions Wood extractives, lignin, suspended solids and certain trace elements were determined in each fraction Forty four percent of the resin and fatty acids

in the influent (12.8 mg/L) occurred in particles, 20% as colloids (0.45 mm–3 kDa) and 36% in the fraction The corresponding values for sterols (1.5 mg/L) were 5, 46 and 49%

In the effluent, resin and fatty acids (1.45 mg/L) and sterols (0.26 mg/L), as well as a small proportion in particles b-sitosterol was present in particles in the effluent (88 _ 50 mg/L) [14]

The used effluents were obtained from the biggest pulp and paper mill In the mill produces about 140 t/d of pulp from soft and hard woods A six-stage bleaching process chlorination, extraction, hypochlorite, chlorine dioxide, extraction, chlorine dioxide is useful to the cooked Kraft pulp Combined leaching chlorination, extraction,

hypochlorite, chlorine dioxide, extraction, chlorine dioxide and the first three steps of the bleaching effluents constitute 30% and 60% of the total flow rate of pulp mill effluent, respectively Spent effluents from the individual bleaching stages of were used in the ozonation experiments The pretreated chlorination, extraction, hypochlorite stage

bleaching effluent was mixed with effluents from other stages of the bleaching process and all other streams of the mill at a ratio of 1:1:1.39 Algal treatment was applied to both raw and pre-treated combined effluents [15] Of the wood Although the existence of

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chlorinated compounds in the effluents has decreased, a discussion about the possible environmental effects of elemental-chlorine-free (ECF) and total-chlorine-free (TCF) bleached pulp mill effluents has arisen, and chronic effects on aquatic organisms have still been found[16] The characteristics of the wastewater generated from various

processes of the pulp and paper industry depend upon the type of process, type of the wood materials, process technology applied, management practices, internal recirculation

of the effluent for recovery, and the amount of water to be used in the particular process and others are generated in the pulp and paper making process show in figure 3

Pollution from the pulp and paper industry can be minimized by various internal process changes and management measures such as the Best Available Technology (BAT)

Therefore, there were necessary to bring in some kind of treatment of the

wastewater For the treatment method and increased knowledge about the underlying processes, there is a complete preference of different mechanical, physical, chemical and biological methods that can be combined in different ways in order to achieve cost

efficient wastewater treatment The wastewater composition and the amounts of different substances in wastewater, and one fundamental dissection are between dissolved

substances and particular matter For the common methods are analyses of total solids (TS), total suspended solids (TSS), and volatile suspended solids (VSS), one more large division is between inorganic and organic compounds The determination of ammonium - nitrogen, other phosphate and nitrate-nitrogen are examples of some of these specific methods Organic compounds are applying measured by lumping methods, such as total organic carbon (TOC) and dissolved organic carbon (DOC) A lot of method have been developed in order to determine how much pollutants a wastewater is made are chemical oxygen demand (COD) and biological oxygen demand (BOD) However, have many different methods represent the most common ones in the wastewater treatment field The mainly important method for characterizing the wastewater is COD Beside that methods comparable to TOC could also be used but then they have to be correlated to COD The amount of degradable matter in the wastewater can be determined with BOD but this method while only gives an estimate VSS is the best measure of the amount of microbial biomass in the wastewater treatment plant TSS could also be used but inorganic matter could bias the result and cause an overestimation of the amount of microorganisms in the

The wastewater generated from digester house is called

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Figure 4 Pollutants from various sources of pulping and papermaking [11]

1.3 Some methods commonly using to treat with the wastewater

1.3.1 Physicochemical treatment

Physicochemical treatment processes include removal of suspended solids, colloidal particles, floating matters, colors, and toxic compounds by sedimentation, flotation, screening, adsorption, coagulation, oxidation, ozonation, electrolysis, reverse osmosis, ultrafiltration, and nano-filtration technologies

1.3.1.1 Coagulation and precipitation

Chemical coagulation followed by sedimentation is a probed technique for the treatment of high suspended solids wastewater especially those formed by colloidal matters Research and practical applications have shown that coagulation will lower the pollution load and could generate an adequate water recovery Coagulation and

flocculation is normally employed in the tertiary treatment in the case of pulp and paper

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mill wastewater treatment and not commonly adopted in the primary treatment It carried out a comparative study of horseradish peroxide (chitosan) and other coagulants such as (Al2(SO4)3), hexamethylene diamine epichlorohydrin polycondensate (HE),

polyethyleneimine (PEI), to remove adsorbable organic halides (AOX), total organic carbon (TOC), and color [9] Coagulation is mainly induced mainly reduced by inorganic metal salts, e.g aluminum and ferric sulphates and chloride Polyelectrolytes of various structures, e.g polyacrylamides, chitosan, polysaccharides, polyvinyl and many more are usually used as coagulant aids to enhance the formation of larger floc in order to improve the rate of sedimentation According to A.L Ahmad, S.S Wong, T.T Teng, A Zuhairi [17] pulp and paper mill wastewater was treated by using the alum and polyaluminum chloride (PACl) alone and in coupled with cationic polyacrylamide (C-PAM) and anionic polyacrylamide (A-PAM) The reduction efficiency of turbidity and chemical oxygen demand (COD), removal efficiency of total suspended solids (TSS), sludge volume index (SVI) and settling time are the main evaluating parameters In coagulation–flocculation process using single coagulant, coagulant dosage and pH play an important role in

determining the coagulation efficiency At the optimum alum dosage of 1000 mg/L and optimum pH of 6.0, turbidity reduction is found to be 99.8%, TSS removal is 99.4% and COD reduction is 91% The optimum dosage and pH for PACl are 500 mg/L and 6.0, respectively, at which it gives 99.9% reduction of turbidity, 99.5% of TSS removal and 91.3% of COD reduction A combination of inorganic coagulant and flocculant or

polymer is applied in which alum and PACl are used coupled with the C-PAM

(Organopol 5415) and A-PAM (Chemfloc 430A) Overall, alum coupled with Organopol

5415 is the best system among all systems studied It gives 99.7% reduction of turbidity, 99.5% removal of TSS and 95.6% reduction of COD, and at the same time with low SVI (38 mL/g) and low settling time

The combined method (coagulation followed by photocatalysis) has been

developed by Angela Claudia Rodrigues et al [18] to improve the efficiency of the treatment of wastewater from pulp and paper mill factories First, the effluent was

submitted to the coagulation–flocculation treatment by applying FeCl3 as the coagulating agent and chitosan as an auxiliary In sequence, the aqueous soluble phase obtained from the first treatmentwas submitted to a UV/TiO2/H2O2 system using mercury lamps The optimized coagulation experimental conditions were chosen: pH 6.0, 80 mg L−1 of

FeCl3·6H2O, and 50 mg L−1 of chitosan The optimized photocatalysis conditions were:

pH 3.0 in 0.50 g L−1 of TiO2 and 10 mmol L−1 of H2O2 COD values for the in natura sample was 1303 mg L−1 and after the optimized conditions of coagulation without

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chitosan and in chitosan presence were 545 and 516 mg L−1, respectively Effluent

turbidity decreased sharply after coagulations (from 10 FTU of in natura samples to 2.5 FTU without chitosan and 1.1 FTU with chitosan) Similarly, a decrease was observed for concentrations of N-ammoniac, N-organic, nitrate, nitrite, phosphate, and sulfate ions after coagulation Additionally, it was observed an absorbance reduction of 90% at the wavelength of 500 nm and of 70–80% in regions corresponding to aliphatic and aromatic groups (254, 280, and 310 nm) The use of chitosan for quantitative purposes was not so efficient; however, it improves sedimentation and compaction COD results of

photolyzed samples by UV/H2O2 were 344 mg L−1, UV/TiO2 326 mg L−1, and

UV/TiO2/H2O2 246 mg L−1 The reduction in absorbance intensity was approximately 98% for aliphatic and aromatic chromophores, and 100% for chromophores absorbing at

500 nm with color disappearance The wastewater treatment carried out in association at optimized experimental conditions provided good results

1.3.1.2 Adsorption

Adsorption is the incorporation of a substance in one state into another of a

different state (e.g liquids being absorbed by a solid or gases being absorbed by a liquid)

Is the physical adherence or bonding of ions and molecules onto the surface of another phase (e.g reagents adsorbed to solid catalyst surface) Amongst various tertiary

treatment processes, adsorption has been found to be attractive for the removal of most organic compounds in wastewaters, especially at lower concentrations Activated carbon has been the most commonly used adsorbent However, high cost of activation, and regeneration and the disposal of the concentrate from the cleaning cycles pose problems

in the use of activated carbon Hence, the search of new low cost adsorbents has attracted

a number of investigators Several low cost adsorbents like wood, coir pith, coal fly ash, bagasse fly ash (BFA) and coal-fired boiler bottom ash have been used for the treatment

of a wide variety of wastewaters A high removal of color by activated charcoal, fuller’s earth, and coal ash have reported The removal of color, COD, DOC, and AOX from bleached wastewater by the adsorption process, using activated coke as an adsorbent have concluded by activated carbon and ion exchange The lignin removal efficiency to reduce color and chloride to levels acceptable for reuse have investigated [17-19]

Accordimg by [20] has reposted the adsorption process was performed at ambient temperature in an orbital shaker cum incubator During the test, 50 ml of wastewater was added in five conical flasks In ecach flask, different amounts activated carbon was

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added After optimizing the adsorbent dose, pH of the wastewater was adjusted by adding 1MNaOH or 1.8 M H2SO4 The flasks were then shaked at 120 rpm for 1 h duration The treated samplees were filtered by passing through a filter paper and the filtrate was

analyzed for different parameter(such as pH, COD and TOC)

1.3.1.3 Chemical oxidation

Chemical oxidation were most commonly employed to date include peroxide, ozone, and permanganate Advanced oxidation processes (AOPs) such as ultrasonic irradiation in combination with Fenton-like oxidation(Fe3+/H2O2) or photo-Fenton

degradation (Fe2+/H2O2/UV) were also separately tested Effects of operating parameters such as pH and oxidant's dose on the removal of organic compounds were investigated in terms of COD removal [18] Chemical oxidation of Kraft pulp bleaching wastewater was investigated by many researchers [17] showed that the use of horseradish peroxide to decolorize Kraft effluent by 50% within three hours of reaction time The degradation of phenolic and polyphenolic compounds present in the bleaching effluent was studied using advanced oxidation systems such as photocatalysis with O2/ZnO/UV, O2/TiO2/UV, O3

and O3/UV The authors concluded that O2/ZnO/UV and O2/TiO2/UV were the best systems to oxidize the effluent in a short period of time The combination of Fenton and photo-fenton reactions proved to be highly effective for the treatment of bleaching Kraft mill effluent Ozonation is a process for infusing water with ozone, this is commonly done to kill bacteria and other organisms, but also for color, taste and odor control [19] All ozonation experiments were carried out at room temperature (23-300C) in a semi-continuous glass reactor (230 mL) with the initial ozone concentration of 30 mg/L during

60 min The ozone/oxygen mixture, with the gas flow of 0.5 mL/min, by the porous ceramic in the inferior part of the reactor was distributed The ozonation of the diluted and filtered samples after precipitation was carried out at the initial pH 1, 3, 8 and 12 [21]

D Pokhrel, T Viraraghavan [9] have give overall reviews of application of the ozonation processes for the removal of COD, TOC, and toxicity from pulp mill effluent and increased biodegradability of the effluent were achieved after treatment with ozone Their summarized that a 90% removal of ethylenediaminetetraacetic acid (EDTA) and a 65% removal of COD by ozone treatment of the pulp mill effluent after 60 min of ozo nation total organic carbon, total phenols reduced to 12% and 70% respectively, and effluent colors to 35% of bleached pulp mill effluent Several authors reported on toxic compounds, COD, and color removal by ozone treatment Some authors indicated that a high dosage of ozone (100–300 mg/ dm3) was required to remove 50% of lippphilic wood

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extractives The ozone doses of 0.2 mgO3/initial mg COD can eliminate over 90% resin acid High removals of TOC, COD, AOX, and color from bleached kraft mill effluent (BKME1) using heterogeneous photocatalysis and ozone treatment can be achieved by ozonation and adsorption

1.3.2 Membrane filtration

The treatment techniques which have been experimented during this study are ozonation, chemical coagulation-flocculation, and activated carbon adsorption and membrane filtration Therefore the application of two or more such treatment techniques has a higher capability for removing a variety of compounds Hence the combination of these techniques is another option to treat Kraft pulp mill effluent which contains several

compounds Membrane filtration has 10% strong effluent samples were prepared by

diluting Kraft pulp mill effluent in distilled water Sample pH was adjusted to different levels (4, 7 and 10) 100 mL samples were filled into cellulose membrane sacks The sacks were kept dipped in 1000 mL distilled water baths for 24hrs and removed Samples for ozonation were taken from the water bath, which contained effluent molecules passed through the membrane [22] However, membrane filtration is defined under the rule as a pressure or vacuum-driven separation process in which particulate matter larger than 1

mm is rejected by an engineered barrier, primarily through a size exclusion mechanism, and which has a measurable removal efficiency of a target organism that can be verified through the application of a direct integrity test The membrane surfaces were

characterized inter of the mean roughness (Ra), the root mean squarer roughness (Rrms) and the mean difference in height between the highest and the five lowest point (Rz) Membrane characterization are Atomic force microscopy (AFM) imaging allowed comparison of surface of clean and fouled membrane and Scanning electron

microscopy(SEM) measurements were used to provide detailed structural

information of membranes including pores inside the membrane [23]

According by E.Dialynas, E.Diamadopoulos [24] has reported high removals were also observed for various heavy metals The removal values were above 90% for

Co, Ni, Mn, and Sr Ultrafiltration membranes can achieve similar results for heavy metals when they are used in a membrane bioreactor (MBR) system arrangement,

effluent pH showed small variation and it ranged between 8.0 and 8.1, and the

ultrafiltration owing tovast improvement in their manufacturing technologies, now posseess very high permeability This has allowed many ultrafiltration applications operate under much lower trasmembrane pressure, as low as 7 KPa (1.01 psi) according

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by [25] has reported the treatment of wastewater of paper mill with integrated membrane process; the conventional treatment can not meet the requirements of water quality for the paper making process The integrated membrane process in pilot scale which consists of the membrane bioreactor (MBR), the continuous membrane filtration (CMF) and the reverse osmosis (RO) is used to treat the wastewater of this paper mill The discharged water from the first sedimentation tank was treated with the anoxic/aerobic/MBR

membrane system to eliminate NH3–N and dissolved organic compound

1.3.3 Biological treatment

1.3.3.1 Aerobic treatment

Aerobic treatment use of free or dissolved oxygen by microorganisms (aerobes)

in the degradation of organic wastes Since oxygen is available to working aerobes as an electron acceptor, the biodegradation process can be significantly accelerated, leading to increased throughput capacity of a treatment system There are numerous biological treatment systems available, the most common being the activated sludge process The distribution of organic loading rate values is similar The full range of operational

parameters of a typical activated sludge plant treating effluent from pulp and paper mills The performances achieved by activated sludge plants being used for the treatment of paper mill wastewaters That very high removal efficiency can be obtained both for BOD and COD removal Aerobic cultures were obtained from the aeration tanks of the

activated sludge units of the Ankara Municipal Wastewater Treatment Plant, Turkey, with a sludge age and organic loading of 2.8 days and 165,000 kg BOD5/day,

respectively [9], [26]

Several authors [17] have reported a high reduction of BOD and soluble COD by

a two-stage activated sludge process They suggested upgrading the activated sludge plant by the addition of Floobeds (floating biological bed) in series that increased COD and BOD removal from 51% to 90% and 70% to 93%, respectively The microorganisms such as Pseudomonas putida, Citrobacter sp., and Enterobacter sp were found efficiency for the removal of color, BOD, COD, phenolics, and sulfide in the activated sludge process The removal of chlorinated phenols, 1,1-dichlorodimethyl sulfone (DDS), and chlorinated acetic acids in an oxygen activated sludge effluent treatment plant were also reported The removal of 90% BOD7, 70% COD, 40–60% AOX, and 60–95% chlorinated phenols removal in the activated sludge process was achieved Stuthridge and Mcfarlane (1994) stated that 70% removal of the AOX from the aerated lagoon was attributed to a short residence time section of the treatment system where the chlorinated stage effluents were mixed with general mill wastewaters The effect of simple mixing was reported to

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be responsible for 15–46% removal Other researcher reported removal of BOD7 ranging between 50% and 75% and chlorinated phenolics 10–50% by an aerated lagoon High removals of organic pollutants of Kraft mill wastewater by sequencing batch reactor (SBR) treatment have reported by other researchers The removal of methanol COD sols are 100% and 90% respectively by SBR Substantial removal of COD, TOC, BOD, lignin and resin acids of TMP wastewater using high rate compact reactors (HCRs) at a

retention time of 1.5 h had been reported Removal of COD by a moving bed bifilm reactor (MBBR) had been demonstrated and concluded that suspended carrier biofilm reactor (SCBR) was highly efficient in removing chronic toxicity from the effluent The use of a biofilter can achieve 76%, 62%, 81%, and 48% removal of BOD, COD, SS, and AOX, respectively Typical efficiencies of aerobic systems are presented in a table 4

Table 4 Typical efficiencies of aerobic systems [9]

time (day)

Organic loading (lb BOD/1000 ft 3 )

generated at an integrated newsprint mill COD and sulphur removals were 66 percent and 73 percent, respectively In general, anaerobic digestion is carried out at mesophilic temperatures, 35 to 37°C However, the use of the thermophilic temperature range is value considering as it will give faster reaction rates and a higher gas production rate [9]