Bubbleless aeration for ammonia oxidation in wastewater treatment using membrane biofilm reactor mbfr

Bubbleless aeration for ammonia oxidation in wastewater treatment using membrane biofilm reactor mbfr Bubbleless aeration for ammonia oxidation in wastewater treatment using membrane biofilm reactor mbfr Bubbleless aeration for ammonia oxidation in wastewater treatment using membrane biofilm reactor mbfr Bubbleless aeration for ammonia oxidation in wastewater treatment using membrane biofilm reactor mbfr Bubbleless aeration for ammonia oxidation in wastewater treatment using membrane biofilm reactor mbfr

THAI NGUYEN UNIVERSITY UNIVERSITY OF AGRICULTURE AND FORESTRY

PHAM VIET HUNG

BUBBLELESS AERATION FOR AMMONIA OXIDATION IN WASTEWATER TREATMENT USING MEMBRANE BIOFILM

REACTOR (MBfR)

BACHELOR THESIS

Study Mode : Full-Time

Major : Environmental Science and Management

Faculty : International Programs Office

Batch : 2013 - 2017

THAI NGUYEN - 2017

DOCUMENTATION PAGE WITH ABSTRACT

Thai Nguyen University Of Agriculture And Forestry

Thesis Title:

BUBBLELESS AERATION FOR AMMONIA OXIDATION

IN WASTEWATER TREATMENT USING MEMBRANE BIOFILM REACTOR ( MBfR)

Supervisor (s):

Professor Chun-Hsiung Hung, National Chung Hsing University, Taiwan

Assoc Prof Dr Nguyen The Hung - Thai Nguyen University

of Agriculture and Forestry, Vietnam

Abstract:

A hollow fiber membrane reactor was utilized to create a halfway nitrification reactor as a pre-treatment framework for ANAMMOX supplement removal Using a silicone membrane to limit oxygen exchange, a biofilm treatment system was made, with biomass attaching on the membrane surface The framework operated at room temperature with a very low dissolved oxygen concentration Nitrite production was evident, with little nitrate created in the system The framework treated high ammonium concentration and low ammonium concentration Ammonium oxidizing organisms dominated the microbial group, while nitrite oxidizing bacteria were suppressed and growth was limited This verified that a low dissolved-oxygen condition selects for AOB, and the silicone membrane is an effective method of controlling oxygen transfer

Key-words: Hollow fiber, ANAMOX, silicone membrane, AOB,

dissolved oxygen concentration

Supervisor‟s

signature

ACKNOWDLEDGEMENTS

I would like firstly to emphasize the sincere appreciation to lecturers in the Advanced Education Progarm (AEP) as well as lecturers in Thai Nguyen University of Agricultural and Forestry, who have lectured me profound knowledge not only for my subjects but also for my soft skills and gave me a chance to do my thesis abroad In addition, I would like to thank all supports and help from Civil and Environmental Engineering Department, National Chung Hsing University for the time I conducted

my research in Taiwan

It is my pleasure to work with a profound supervisor - Professor Chun-Hsiung

Hung, who always helped me whenever I am in need He also provided me the best

conditions, supported all materials for my research and discussed about any problems I got whenever I did experiments in his Biotechnology Lab

I would like to give special thank to Associated Professor Nguyen The Hung,

who always supported and cheered me up whole the time I worked oversea He also helps me a lot in spending much time for checking my thesis report

I consider it is an honor to work with Mr Lin and Ms Wendy, 2 exceptional

master students, who particularly helpful in guiding me toward a qualitative methodology and inspiring me in whole period of internship time They are always helpful, friendly and very kind with me Without their guidance, I cannot accomplish this thesis

Finally, I would like to express my gratitude to my family and friends, who always beside me all the time Their helps, supports and encouragements created the pump leading me to success

Sincerely, Pham Viet Hung

TABLE OF CONTENTS

DOCUMENTATION PAGE WITH ABSTRACT 1

ACKNOWDLEDGEMENTS 3

TABLE OF CONTENTS 5

LIST OF FIGURES 6

LIST OF TABLES 7

LIST OF ABBREVIATIONS 8

PART 1: INTRODUCTION 9

1.1.Research Rationale 9

1.2.Research‟s Objectives 10

1.3.Definitions 10

PART 2: LITERATURE REVIEW 13

2.1 Nutrients in wastewater: 13

2.2 Nitrogen Removal Procedures: 14

2.3 Source-separated urine 14

2.4 Models for bubble-less oxygen transfer 15

2.5 MBfR as biofilm treatment system 15

PART 3: METHODS AND MATERIALS 17

3.1 Materials: 17

3.2 Selection of Method: 19

3.3 Preparation of the medium: 21

3.4 Analyzing the water samples: 23

PART 4: CONCLUSION 46

REFERENCES 47

LIST OF FIGURES

Figure 1: The Ion Chromatography Equipment 24

Figure 2: Chromatogram and Results of AOB in (03/27/2017) 25

Figure 3: Chromatogram and Results of water samples in Control tube (04/05/2017) 26

Figure 4: Chromatogram and Results of Water sample in Test tube (04/05/2017) 28

Figure 5: Chromatogram and Results of Water samples in Control tube (04/10/2017) 29

Figure 6: The Chromatogram and Results of Water samples in Test tube (04/10/2017) 30

Figure 7: The Chromatogram and Results of Water samples in Control tube (04/17/2017) 31

Figure 8: The Chromatogram and Results of Water samples in Test tube (04/17/2017) 32

Figure 9: The Chromatogram and Results of Water samples in Test tube (04/24/2017) 33

Figure 10: The Chromatogram and Results of Water samples in Control tube (01/05/2017) 35 Figure 11: The Chromatogram and Results of Water samples in Test tube (05/01/2017) 36

Figure 12: The Chromatogram and Results of Water samples in Control tube (05/08/2017) 37 Figure 13: The Chromatogram and Results of Water samples in Test tube (05/08/2017) 39

Figure 14: The Chromatogram and Results of Water samples in Control tube (05/15/2017) 40 Figure 15: The Chromatogram and Results of Water samples in Test tube (05/15/2017) 41

Figure 16: The Chromatogram and Results of Water samples in Control tube (05/22/2017) 42 Figure 17: The Chromatogram and Results of Water samples in Test tube (05/22/2017) 44

LIST OF TABLES

Table 1: Nitrogen metabolisms related to wastewater treatment 13

Table 2: The amount of constituents in the medium 18

Table 3: (*)Trace element solution in the medium 19

Table 4: The exact amount of chemical compounds for preparation of medium 22

Table 5: Summary of the Chromatogram Results by NO2- component 34

LIST OF ABBREVIATIONS

MBAR Membrane Aerated Biofilm Reactors

LDL Low Density Lipoprotein

SRT Solid Retention Time

AOB Ammonia-oxidizing Bacteria

PART 1: INTRODUCTION

The membrane biofilm reactor (MBfR) is a mechanical treatment which depends

on gas-exchanging membranes The membranes typically supply a vaporous electron donor or acceptor substrate, such as hydrogen, oxygen and methane The electron substrate diffuses through the membrane to a biofilm and shaping on the membrane in the outside of the surface Biofilms procedures are of bringing the interest in environmental science and biotechnology due to its capacity to accumulate the high biomass densities and hold it inside the reactor Almost all the biofilm procedures are based on attachment surfaces, such as stone, dense plastic, plastic foams Both electron donor and acceptor substrates are supplied from the bulk liquid which can be called „co-diffusional‟ biofilms The biofilms can also grow on reactive surfaces that release electron acceptor or donor substrate into the biofilm

Counter-diffusional biofilms can likewise be found in natural frameworks and built frameworks In environmental systems, counter-diffusional biofilms can be found

on gas-fluid interfaces, such as plant roots, air bubbles and the roots may supply organic exudates or oxygen to biofilms creating on their surface In engineered systems, counter-diffusional biofilms can grow on inorganic solids such as elemental sulfur or organic solids such as chitin and biodegradable polymers

Membrane-biofilm reactor is an essential counter-diffusional biofilm procedure in the environmental biotechnology It is depended on gas-permeable membranes that deliver a gaseous substrate to biofilms naturally forming on the membrane the

outer surface areas The procedures with the supply of air or oxygen are called Membrane aerated biofilm reactors (MABRs) This engineered procedure has been studied since the 1970s but it has gained intense interest from the researchers in recent years Also, the technologies have been launched in commercial technologies in recent years

With co-diffusional biofilms, the most metabolically active region of the biofilm is normally the exterior, the electron donor and acceptor substrates are at their highest concentrations The most active zone is typically situated in the interior of the biofilm This counter diffusion of donor and acceptor leads to unique behavior which contains three primary differences: development of unique microbial community structures, greater sensitivity to biofilm accumulation and reduced susceptibility to liquid diffusion layer resistance

1.2 Research’s Objectives

The objective of this research is to test the novel method of wastewater treatment

by using the membrane-biofilm reactors The expected results would produce nitrate from the reactor and create insignificant amount of nitrate

1.3 Definitions

Development of unique microbial community structures:

The counter diffusion of substrates can lead to unique microbial community structures

in the membrane-biofilm reactors Most of biofilms for wastewater treatment , the aerobic nitrifying microorganism grow in the deeper regions of the biofilm where the

competition from heterotrophic microorganisms It is also the location when the concentration of oxygen gets lowest which leads to low nitrification Oxygen is supplied from the base of the biofilm so the nitrifiers experience low organic carbon and high oxygen concentrations, promoting high nitrification activity This unique stratification may favor suppression of nitrite-oxidizing organisms (NOB)

Greater sensitivity to biofilm accumulation:

In conventional biofilms, the initial contaminant transformation fluxes are low, due to low biofilm thicknesses The fluxes then increase as the biofilm thicknesses increases, until the biofilm growth is balanced by decay and detachment In counter-diffusional biofilms, fluxes rise up to a point but then reduce as the thickness increases further This is because of donor acceptor counter diffusion The biofilm interior has low activity due to the limitation of one substrate, while the exterior has low rates due to the limitation of the other

Lower susceptibility to LDL resistance:

In a conventional biofilm, the LDL limits substrate fluxes into the biofilm As the biofilm thickness and flux increase, the biofilm, the LDL provides a barrier to loss of the internal substrate to the bulk liquid As long as the substrate from the bulk is present at non-rate limiting concentrations, the LDL will not limit and may actually enhance, microbial activity

In addition to the aforementioned, the mode of gas supply and biofilm development in the membrane-biofilm reactors can lead to special behavior For instance, when gas is supplied via hollow-fiber membranes, other dissolved gases in the bulk liquid, gases

formed in the biofilm, can diffuse back into the membrane, diluting the supply gas When operating an MBfR with sealed membranes, these gases concentrate at the distal end of the membrane, decreasing its effectiveness and leading to thinner biofilms Also several hollow-fiber membranes can clump together, effectively forming one large biofilm with individual membranes which provides point gas sources in the biofilm interior

Biofilms can assume uneven or rough morphologies, which result from an interplay between cell growth rates, shear conditions, microbial cell types, and other factors The roughness of counter-diffusional biofilms can affect their behavior In particular, roughness increases the effective LDL thickness, which limits fluxes in conventional biofilms The fluid flow regime is important for all biofilm processes Thus, computational fluid dynamics can be an important tool for membrane-biofilm reactors studies, either to determine the flow regime around membranes or to couple with a model of biofilm growth and deformation It is especially essential when biofilm-covered membranes contact each other, as they may bundle and cause dead zones without flow The bundle might behave like a singular with gaseous substrates sources

in the interior

PART 2: LITERATURE REVIEW 2.1 Nutrients in wastewater:

In municipal wastewater, the priority of nitrogen is in the reduced form, for instance, organic amine group R-NH3 or R-NH4, ionized ammonium NH4+ or free ammonia

NH3 During collection process, most of the organic nitrogen in wastewater is ammonified to NH4+ The terms ammonia and ammonium are used to refer to the decreased form of inorganic nitrogen Total nitrogen removal requires denitrification

to nitrogen gas which are released to the air In addition, the sufficient oxygen and organic carbon present the majority of resources associated with conventional nitrification and denitrification There are multiple step processes of nitrification and denitrification, demonstrated in the Table 2

Table 1: Nitrogen metabolisms related to wastewater treatment

Nitrogen Oxidation State

2.2 Nitrogen Removal Procedures:

In conventional nitrogen removal processes, there are many beneficial uses in environmental engineering systems Nevertheless, these procedures are not ideal for treating specialized wastes with the high concentrations of decreased N species, they require spatial separation in the form of dedicated tank and high amounts of organic carbon, oxygen and alkalinity However, in the recent years, novel nitrogen removal processes have been explored and developed, this made the possibility of significant resources and cost saving While some of the novel nitrogen removal processes, some

of them have been presented and discussed in the realm of emerging science and beginning to be applied around the world

a Nitritation and Denitritation

b Anaerobic ammonium oxidation

c Nitritation and Anaerobic ammonium oxidation

2.3 Source-separated urine

One type of specialized wastewater is emerging as engineers and researchers consider more decentralized, such an approach lends itself well to water reuse The majority of both nitrogen and phosphorus in wastewater is separated from urine and reduced the nitrogen concentrations Thus, more efficiency can be gained from decentralized treatment if the high-strength wastewater is treated differently from the other wastewater resources that dilute it Biological Nitrogen removal from the separated urine sources has gained limited study and research about those issues When the advanced Nitrogen removal has been gaining more attention from the engineers and

scientists, it is possibly that the source-separated urine will maintain to be the good choice for their application in wastewater treatment

2.4 Models for bubble-less oxygen transfer

There are many research of oversizing and undersizing aeration system have been dedicated to the developing predictive models for aeration The ability to predict oxygen transfer in membrane systems is a primary factor in wastewater treatment Many of the models are suitable for microporous membranes where the gas phase is importantly in contact and equal to the pore liquid at the base of biofilm (Shanahan and Semmens, 2004) In the case of microporous membranes, the DO concentration in the pore liquid is high and near saturation point Contrast to the non-porous membranes such as silicone rubber with a sorption-dissolution-diffusion mechanism and exhibits an oxygen gradient across the thickness of the membrane

2.5 MBfR as biofilm treatment system

The biofilms bring the great advantages over the suspended growth in wastewater treatment systems Through biomass retention, spatial metabolic of organisms, resistantace to shock all the characteristics of the biofilm arrangement, these systems have the favored position of supplying counter current mass transfer of oxygen from the sub-stratum of the biofilm and in the adverse direction of the nutrient diffusion from the bulk liquid The application of the MBfR to wastewater treatment contains both typical and novel metabolic compositions which indicated the perception of treating manufactured municipal sewage water with sealed-end microporous hollow-fiber membrane Due to the counter-current distribution of electron donor and acceptor

yields micro-environment quite distinct from the traditional co-current biofilm, much research has been directed at demonstrating the microbial communities that develop the MBfR systems

PART 3: METHODS AND MATERIALS 3.1 Materials:

Hollow fiber membrane selection A silicone membrane was chosen for oxygen delivery based on its physical attributes Air diffuses through the silicone membrane and forms small bubbles on the silicone surface The silicone membrane provides an air circulation surface for oxygen transfer, without bubble discharge from the membrane, unlike a typical air-sparging aerator A bubbleless reactor is consequently made, and biomass is not blown away from the membrane by the air bubbles This mechanism enables biomass to connect to the silicone membrane and expand the accessible oxygen before the oxygen reaches the bulk solution In this manner, bulk 42 dissolved oxygen remains low (less than 0.1 mg/L), while oxygen-consuming organisms grow on the silicone membrane Additionally, attached growth is ideal for nitrifying autotrophs Membrane aeration systems provide available surface area for biofilm attachment; a biofilm system takes advantage of long sludge age to aid in culturing nitrifying organisms Due to the slow-growing nature of nitrifying organisms, a biofilm or granule structure allows for an increase in biomass concentration and solids retention time (SRT)

Partial nitrification reactor configuration The reactor configuration for the partial nitrification study employed a long glass tube reactor with a recirculation reservoir for sampling and monitoring pH and dissolved oxygen The reactor is 122 cm long, 2.5

cm outer diameter, and 2.29 cm inner diameter, for a reactor volume of 300 mL The reactor incorporates a single silicone membrane fiber The silicone membrane is the length of the reactor, and has an outer diameter of 2.0 mm, and a wall thickness of

0.25 mm A recirculation pump cycled the wastewater to be treated through the membrane reactor and into the reservoir

The calculated flow-rate is quite low The low flow-rate of the gas permeation through the silicone membrane creates an environment which is ideal for maintaining a low dissolved oxygen in the bulk solution This creates a system which can be classified as

“bubbleless.” Few previous partial nitrification studies have been performed using a bubbleless system Previously, researchers have controlled the gas flow-rate In this research, the system was operated at a constant pressure, allowing for consistent operation of the system, and eliminating the need for aeration control

AOB medium (150 ml) pH = 8.2 Table 2: The amount of constituents in the medium

-N/L

Stock solution conc

The amount needed

Table 3: (*)Trace element solution in the medium

Trace Element Solution

- connection cable for pH electrode

Since the pH measurement is influenced by temperature variation, to correct this type

of alteration, mostly of pHmeters are completed with temperature probe to compensate the electrode‟s answer

3.2 Selection of Method:

There are two factors which influence the selection of the method to evaluate the Ammonia are concentration and the existence of interferences In general, the

direct physical determination of low concentration of Ammonia is limited to drinking water, clean surface water, and the ideal-quality nitrified wastewater runoff

Treatment process:

Biological Treatment: Biological Decomposition Processes:

The organic components are comprised of carbon combined with the other elements such as oxygen, hydrogen, nitrogen, phosphorus, sulfur, and others Nevertheless, the organic elements in sewage are not pure organic compounds in chemical issues, they are decomposable remainder of living procedures of humans, animals and plants Among these compounds the most essential are urea and proteins which consist of nitrogen added to carbon Some proteins also consist of sulfur as a result of disintegration, produce annoyingly smelling hydrogen sulfide gas Chemically, the wastewater compounds can manage oxygen in two distinct ways: they can gain oxygen and/ or lose an electron which is called oxidation or they can lose oxygen and/ or gain an electron which is called reduction

The organic compounds in sewage are mostly remainder of decomposed reduction procedure of plants and animals matter The microorganisms and oxygen have the charge of converting these rather than unstable components into more stable, oxidized compounds

Bacteria, especially the aerobic species, are the means of assassinating these biochemical reactions, as long as free oxygen from the water is accessible When the point of supply are exhausted, the aerobic bacteria is replaced by anaerobic or optional microorganisms that draw upon the oxygen contained in organic matter and in

substances such as nitrates, nitrites and sulfates In a nutrient rich environment, small cellular microorganisms can build communities that are then visible to the eyes In waste treatment units, these may be seen as suspended slimy flocs in the activated sludge units The higher organisms such as protozoa and lower animals can live symbiotically with the bacteria

The bacteria are impressionable to acids and bases in about the similar degree Therefore, the pH value of water should not considerably deviate from 7 and fluctuating and pH shocks should be prevented The bacteria are also acquainted to a certain temperature range The exchange of nutrients and waste materials concurrently with the living procedure occurs via the bacterial cell wall, as a result only water, gases and dissolved materials can be exchanged Solids and colloids must be first dissolved This is achieved by enzymes that are emitted via the walls of the cells In a similar way, the used and decomposed residuals during the decomposition procedure are released by the bacteria via cellular walls as gases or liquids The exchange of matter by bacteria is continuous, it works best when the nutrients are in motion or flowing, such as in trickling filters, digestion chambers or experimental BOD…

Aerobic Treatment ( Biological Wastewater Treatment):

In almost all cases refers to aerobic procedure stages or to treatment stages in aerates water The removal of organic pollutants from wastewater cannot be attributed only to bacterial decomposition

3.3 Preparation of the medium:

For the preparation of the medium, we can either use the 300mL bottle or the two 150mL tubes for containing the medium Firstly, preparing 300mL of DI water

contained in the tube, put it in the shaking machine for mixing the medium Secondly, preparing the following constituents: (NH4)2SO4, KHCO3, NaCl, MgSO4 7H2O,

using the pipette to get the solutions in each constituents as the following amounts:

Table 4: The exact amount of chemical compounds for preparation of medium

After adding exact amount of each constituent to the medium contained in the 300mL

DI water tube, using the pH meter benchtop digital microprocessor to determine the

pH condition of the medium When the pH condition of the solutions is not equal to 8.2, we need to make the pH condition equals approximately 8.2 by adding slowly NaOH to the medium until it gets approximately 8.2 of pH condition By adding NaOH to the medium, it will make the solution become more base If we carelessly

add too much NaOH to the medium which makes the pH condition over 8.2, we have

to prepare the medium again due to its pH condition After using the pH meter benchtop digital microprocessor to determine the exact pH value of the medium, we

the medium to 150mL in each two tube and named control tube written by N and Test tube written by Test In each tube, we use the silicon tube attached to the oxygen and nitrogen air supplier For the Test tube, we use needle and add 10mL of the AOB

3.4 Analyzing the water samples:

Ion chromatography (IC) is the separation and quantitative analysis of anions and cations in an ionic solution using the ion exchange method of liquid chromatography (LC) The chromatographic process separates the different ions within the sample The amount of an anion/cation is measured by the change in conductivity as the species passes through the detector

The ions in the sample solution are carried through the system by an ionic solution, or eluent (mobile phase) The different ions in the eluent are separated in a column packed with an ion exchange resin (stationary phase) The resin has a thin surface layer of active material with limited ion exchange sites If anions are to be analyzed, the active sites will have a fixed positive charge to attract the anions Resins for cation analysis will have a negative charge Individual ions attach and detach from the resins

at a rate depending on the affinity of the specific ion to the active sites Ions with greater affinity for the stationary phase are retained in the column for a longer time than those with less affinity for the stationary phase

Thus, the ions of particular chemical species in the solution exit or elute from the column within a narrow time band specific to that ion The detector at the end of the column continuously measures the conductivity of the eluent to determine the quantity

of the eluting ions as a function of time The data from the detector are compiled into a plot of ion abundance versus time, referred to as a chromatogram The position of a peak in the chromatogram is characteristic of a specific ion The peak size is a function

of the concentration for the ion represented by that peak

Anion and cation concentrations can be quantified by establishing a standard curve of known concentrations for each species The peak height or the area under the peak in the chromatogram for each anion or cation is compared to the standardization curve to determine the concentration of the ion the sample

- Preparing the water samples, equipment and needed tools

- Analyzing special clean water used only for the Ion Chromatography procedure

- Analyzing the prepared water samples/ medium

- Based on the peaks to calculate ion concentration through calibration line