Luận văn thạc sĩ Kỹ thuật môi trường: Study of nutrients recovery from poultry wastewater by modified biochar for soil application

VIETNAM NATIONAL UNIVERSITY HO CHI MINH CITY

HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY

-o0o -

NGUYEN LAN THANH

STUDY OF NUTRIENTS RECOVERY FROM POULTRY WASTEWATER BY MODIFIED BIOCHAR FOR SOIL

THIS THESIS IS COMPLETED AT

HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY – VNU-HCM

Supervisor: Dr Vo Thanh Hang

Examiner 1: Assoc Prof Ph.D Nguyen Tan Phong

Examiner 2: Dr Huynh Thi Ngoc Han

This master’s thesis is defended at HCM City University of Technology, VNU- HCM City on 29th July 2023

Master’s Thesis Committee:

1 Chairman: Assoc Prof Ph.D Dang Viet Hung 2 Member : Assoc Prof Ph.D Dang Vu Bich Hanh 3 Examiner: Assoc Prof Ph.D Nguyen Tan Phong 4 Examiner: Dr Huynh Thi Ngoc Han

5 Secretary: Dr Le Thi Huynh Tram

Approval of the Chairman of Master’s Thesis Committee and Dean of Faculty of Environment and Natural Resources after the thesis being corrected (If any)

ENVIRONMENT AND NATURAL RESOURCES

VIETNAM NATIONAL UNIVERSITY - HO CHI MINH CITY

HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY

Independence – Freedom - Happiness

THE TASK SHEET OF MASTER’S THESIS

Date of birth: 13/10/1998 Place of birth: HCM city Major: Environmental Engineering Major ID: 8520320

I THESIS TITLE (In Vietnamese):

Nghiên cứu thu hồi chất dinh dưỡng từ nước thải chăn nuôi bằng biochar biến tính định hướng phân bón

II THESIS TITLE (In English):

Study of nutrients recovery from poultry wastewater by modified biochar for soil application

III TASKS AND CONTENTS:

- Content 1: Biochar preparation and modification

- Content 2: Evaluating factors effect on synthetic wastewater - Content 3: Evaluating factors effect on poultry wastewater

- Content 4: Evaluating the slow-released ability of biochar fertilizer - Content 5: Soil application

IV THESIS START DAY: (master’s thesis decision date) 14/02/2022.

V THESIS COMPLETION DAY: (master’s thesis decision date) 12/06/2023VI SUPERVISOR: Dr Vo Thanh Hang

Ho Chi Minh City, date …,…2023

DEAN OF FACULTY OF ENVIRONMENT AND NATURAL RESOURCES

(Full name and signature)

ACKNOWLEDGEMENT

I would like to express my heartfelt gratitude and appreciation to everyone who has helped me along the way to finishing this thesis Due to a lack of time and knowledge, some of the information in this thesis cannot be sufficient and complete; please be understanding for my shortcoming First and foremost, I want to express my gratitude to Dr Vo Thanh Hang, Assoc Prof Ph.D Nguyen Nhat Huy, M.Sc Lam Pham Thanh Hien, M.Sc Vo Thi Thanh Thuy for their guidance, patience, and invaluable insights throughout the entire research process Their knowledge, encouragement, and constructive criticism were instrumental in shaping the direction and quality of this thesis I am also eternally thankful to our laboratory 710 H2 group members, who has shared their knowledge and provided a stimulating academic environment Their dedication to learning and research has had a significant impact on my intellectual development Furthermore, I would like to acknowledge my friends and family for their unwavering support, encouragement, and understanding throughout this challenging but rewarding academic endeavor Their faith in my abilities and consistent motivation has been critical to my success Lastly, I would like to acknowledge the countless individuals who have contributed in numerous ways, whether through discussions, assistance, or moral support Your contributions may not be mentioned individually, but they have played a key role in shaping my academic and personal growth To all those mentioned and those who remain unnamed, I am profoundly grateful for your support and belief in me This thesis would not have been possible without your contributions

Ho Chi Minh City, July 2023 Nguyen Lan Thanh

ABSTRACT

In this research, we propose and evaluate a novel approach for the treatment of poultry wastewater using a composite adsorbent derived from agricultural waste and water supply sludge The ultimate objective is to transform the treated wastewater into a viable fertilizer suitable for agricultural applications The modified biochar, a key component of the adsorbent, was synthesized by incorporating crop residues, water treatment plant sludge, and magnesium salt The resulting biochar was subjected to a comprehensive characterization process encompassing scanning electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer-Emmett-Teller analysis, and X-ray diffraction Subsequently, the adsorption performance of the modified biochar was assessed with respect to ammonia and phosphate removal, employing both synthetic and actual poultry wastewater samples The study also investigated the influence of various experimental parameters, including the nitrogen-to-phosphorus (N/P) ratio, initial concentrations of ammonium and phosphate, pH, and the quantity of biochar, on the adsorption capacity of ammonia and phosphate The outcomes of the experimental design revealed that the optimal conditions yielded remarkable adsorption capacities of 60.64 mgNH4+-N/g and 66.24 mgPO43--P/g These conditions encompassed an N/P ratio of 1.25, an initial concentration of 90 mg/L, a pH level of 6, and a biochar mass of 0.105 g The optimum value was applied for produced biochar as a fertilizer and assessed for slow-released ability The pink swamp mallow was treated with biochar, chemical and untreated for control sample We cannot conclude the slow-released ability of this biochar, but the plant with biochar treated develop normally like the others

TÓM TẮT LUẬN VĂN THẠC SĨ

Trong nghiên cứu này, chúng tôi đề xuất và đánh giá một phương pháp mới để xử lý nước thải gia cầm bằng cách sử dụng chất hấp phụ tổng hợp có nguồn gốc từ chất thải nông nghiệp và bùn nước cấp Mục tiêu cuối cùng là sử dụng nguồn dinh dưỡng có sẵn trong nước thải trở thành phân bón ứng dụng cho nông nghiệp Than sinh học biến tính, được tổng hợp bằng cách kết hợp phế phẩm nông nghiệp, bùn nhà máy xử lý nước và muối magie Than sinh học thu được được phân tích tính chất bằng các phương pháp hiện đại bao gồm kính hiển vi điện tử quét, quang phổ tia X phân tán năng lượng, phân tích Brunauer-Emmett-Teller và nhiễu xạ tia X Sau đó, hiệu suất hấp phụ của than sinh học biến tính được đánh giá bằng hiệu suất loại bỏ amoni và phốt phát trên cả mẫu nước giả thải và mẫu thực tế Nghiên cứu cũng đánh giá ảnh hưởng của các thông số thí nghiệm khác nhau, bao gồm tỷ lệ nitơ-phốt pho (N/P), nồng độ ban đầu của amoni và phốt phát, độ pH và lượng than sinh học đến khả năng hấp phụ của amonia và phốt phát Kết quả thiết kế thực nghiệm cho thấy các điều kiện tối ưu cho khả năng hấp phụ vượt trội là 60,64 mgNH4+-N/g và 66.24 mgPO43--P/g Những điều kiện này bao gồm tỷ lệ N/P là 1.25, nồng độ ban đầu là 90 mg/L, độ pH là 6 và khối lượng than sinh học là 0.105 g Giá trị tối ưu được áp dụng cho than sinh học được sản xuất làm phân bón và đánh giá khả năng nhả chậm Cây sâm bố chính được bón bằng phân từ than sinh học, và so sánh với phân hóa học cũng như một mẫu đối chứng Kết luận, than sinh học chưa thể đánh giá được khả năng nhả chậm, nhưng cây sâm bố chính sử dụng than sinh học có tốc độ phát triển cũng như tính chất như hai loại đối chứng

THE COMMITMENT OF THE THESIS’ AUTHOR

I hereby declare that this thesis is solely my original work and that the content presented within it is entirely accurate The data and tables used for analysis and guidance in this study have been sourced from various references, and proper attributions are provided in the references or footnotes immediately beneath the respective tables Moreover, to provide additional clarification for the analyzed and referenced arguments, explanatory documents are included in the appendix, along with annotated data sources

Ho Chi Minh City, July 2023

Nguyen Lan Thanh

TABLE OF CONTENT

ACKNOWLEDGEMENT i

ABSTRACT ii

TÓM TẮT LUẬN VĂN THẠC SĨ iii

THE COMMITMENT OF THE THESIS’ AUTHOR iv

CHAPTER 2 LITERATURE REVIEW 5

2.1 Overview of animal agriculture 5

2.2 Environmental affection 6

2.2.1 Polluted by solid waste 6

2.2.2 Polluted by wastewater 8

2.3.1 Mechanical treatment method 12

2.3.2 Physicochemical treatment method 13

2.7.2 The negative effect of sludge 36

2.7.3 Sludge treatment method 37

2.8 Review studies in Vietnam and international 39

2.8.1 In Vietnam 39

2.8.2 International 40

2.8.3 Brief conclusion 41

CHAPTER 3 MATERIALS AND METHODS 43

3.1 Equipment and material 43

3.2 Material preparation 44

3.2.1 Biochar preparation 44

3.2.2 Sludge preparation 45

3.4 Adsorption experiment 46

3.4.1 Evaluating adsorption of biochar and sludge on synthetic wastewater 46

3.4.2 Evaluating adsorption of biochar and sludge on real wastewater 46

3.4.3 Evaluating slow – release 47

3.4.4 Soil application 48

3.5 Analyzing method 48

3.5.1 Ammonium analyzing method 48

3.5.2 Phosphate analyzing method 49

3.6 Calculation 51

3.6.1 Removal efficiency 51

3.6.2 Adsorption capacity 51

CHAPTER 4 RESULTS AND DISCUSSION 54

4.1 The preliminary results 54

4.2 Biochar characterization 56

4.2.1 Surface morphology and pore structure of 10% Mg-biochar 56

4.2.2 Compositions and structure of modified biochar 57

4.3 Optimization 62

4.3.1 Model fitting and statical analysis 62

4.3.2 Interactive effect of variable on models 66

4.4 Optimization results 71

4.4.1 Application on sythetic wastwater 71

4.4.2 Application on actual wastewater 72

4.5 Slow-release experiment 74

4.5.1 Slow release in water 74

4.5.1 Slow release in soil 76

4.6 Soil application 77

4.7 Cost for 5 g of modified biochar 82

CHAPTER 5 CONCLUSION AND RECOMMENDATION 84

ACRONYMS

LIST OF FIGURES

Fig 2.1 Diagram for removal and generation solid liquid pollutants 16

Fig 2.2 The image of biochar 17

Fig 2.3 (a) Mound kiln; (b) Pit Kiln 21

Fig 2.4 (a) Brick Kiln; (b) Metal Kiln 22

Fig 2.5 Loaded technique of biochar for different emphases 24

Fig 3.1 Biochar preparation procedure 44

Fig 3.2 Sludge preparation procedure 45

Fig 3.3 The chicken coop in District 12 47

Fig 3.4 Ammonia analysis method 49

Fig 3.5 Phosphate analysis method 50

Fig 4.1 The influence various types of biochar (with or without sludge) on phosphate and ammonium adsorption capacity 55

Fig 4.2 SEM images of raw material and MgCl2 10% modified biochar a) raw bagasse scaled up x10000 times; b) raw sludge scaled up x10,000 times; c) BS scaled up x 10000 times 56

Fig 4.3 Analyzed element in EDS and % element in material (a) Mg-BS before adsorption; (b) Mg-BS after adsorption; (c) raw water treatment plant sludge; (d) raw bagasse 58

Fig 4.4 XRD analysis of BS before (B-adsorb) and after (A-adsorb) adsorption nutrients from wastewater 60

Fig 4.5 The isotherm plot adsorption and desorption of BS (a), and the pore distribution of BS (b) 62

Fig 4.6 The normal distribution plot of adsorption capacity (a) Ammonium (b) Phosphate 64

Fig 4.7 Normal probability plots of residual for (a) Ammonium adsorption capacity (mg/g) (b) Phosphate adsorption capacity (mg/g) 65

Fig 4.8 The predicted vs actual response values plot for (a) Ammonium adsorption capacity (mg/g); (b) Phosphate adsorption capacity (mg/g) 66Fig 4.9 3D surface plot and perturbation plot of ammonium adsorption capacity 67Fig 4.10 3D surface plot and perturbation plot of phosphate adsorption capacity 70Fig 4.11 The adsorption capacity (a), removal efficiency (b) of phosphate and ammonium ion 72Fig 4.12 Outlet concentration of ammonium and phosphate leachate from water 75Fig 4.13 Outlet concentration of ammonium and phosphate leachate from (a) sand and (b) soil 76Fig 4 14 The Pink Swamp Mallow blooming 78Fig 4.15 (a) the height and (b) largest diameter of pink swamp mallow roots 79Fig 4.16 The expression of Pink Swamp Mallow (a), (b) the flower blooming, (c), (d) (e) leaves of biochar, chemical, and untreated 80Fig 4.17 Qualitative sample extracting fluid from three treated plant (1 – biochar, 2 – chemical, 3 – untreated) (a) raw extracting fluid (b) sample with NaOH 10%, (c) sample 2 times distilled with NaOH 10% 81

LIST OF TABLES

Table 2 1 Chemical composition of manure (following basic factor) 6

Table 2 2 Chemical position of broiler and turkey manure from South California 7

Table 2 3 Characteristics of poultry and swine wastewater 10

Table 2.4 Product (dry %) with different types of pyrolysis 23

Table 2.5 The differences in materials and applications of biochar, activated carbon and regular charcoal 27

Table 2.6 Mass yield of main crops in Vietnam from 2000 to 2020 31

Table 2.7 The characteristic of sludge in water plants in HCM city 35

Table 3.1 Equipment for experiment 43

Table 3.2 Machine for experiment 43

Table 3.3 Experimental range and levels of the independent variables 46

Table 3.4 Standard curve for phosphate concentration 50

Table 4.1 Analysis of variances for fit of phosphate ion, and ammonium ion qe (mg/g) from central composite design 63

Table 4.2 Results of synthetic wastewater for testing the predicted model 72

Table 4.3 Comparison of others research 74

Table 4.4 Properties of root pink swamp mallow 82

Table 4.5 The total price of 5g modified biochar (0% loss) 83

CHAPTER 1 INTRODUCTION

1.1 Motivation

Nowadays, animal agriculture plays an important role in Vietnam agriculture (about 28% of production value) Approximately 4.58 million tons of meat including pigs, cows and poultry were slaughtered in 2014 in Vietnam According to the General Statistics Office in 2012, pork production accounted for 72.6%, while that of poultry, cows and buffaloes was 18, 6.3 and 1.8% respectively [1] Moreover, according to Department of Livestock of Vietnam in 2020, despite all adverse events, global poultry production still grew well, up 1.3% compared to 2020 Total poultry production was about 131.6, 133.4, and 135.2 million tons in 2019, 2020, and 2021, respectively Since 2000, the annual global poultry meat production has continuously increased and surpassed pork production Poultry meat production in 2021 reached 135.2 million tons and accounted for over 40% of total meat production, commercial poultry meat in 2021 reached 15.6 million tons, accounting for over 37% of total commercial meat Due to the following increased consumption demand, farms will spring up all over Vietnam

The spread of spontaneous animal agriculture production is detrimental to the environment industry because these household do not ensure the sanitation of the barns as well as the treatment of waste in a secure manner According to information from the Ministry of Agriculture and Rural Development, animal waste is surveyed about 80 million tons a year, 80% of which is discharged from establishments, small cattle and hennery farms and large farm However, up to 36% of this 80% is discharged directly into the environment without treatment The amount of waste that is directly discharged over time will cause many serious impacts to the water, soil, and air environment around that area Furthermore, the hennery manure and pig manure contains about 70%-90% nitrogen, phosphorus, magnesium, potassium, and others [1] In which, a large amount of phosphorus

and nitrogen (main nutrients in animal agriculture wastewater) discharged into the aquatic environment can cause eutrophication affecting aquatic organisms

Furthermore, Viet Nam is an agricultural country which plays an important role in Viet Nam’s economic According to the Department of Crop Production, Ministry of Agriculture and Rural Development, the waste from paddy field accounted for 50% dry waste, it meant each 1 tons of paddy had nearly 1 tons of waste [2] There are about 61.43 million tons of agricultural waste included 39.9 million tons of straw, 7.99 million tons of rice husk, 4.45 million tons of bagasse, 1.2 million tons sugarcane stalks, … Besides, nearly 80% of the agricultural waste was discharged directly into the environment or burned which was negative affect on the environment [2]

Due to the above problems of the animal agriculture treatment, and the agricultural waste management, some research about those issues needs to be explored Today, the ideas of cleaner production instead of end-of-pipe treatment have been and are being paid attention all around the world Instead of using wastewater treatment methods, present research is focusing on reusing nutrients such as N and P to create another product with economic benefits Furthermore, reused the crop residues and fabricated biochar as an adsorbent for nutrient recovery from poultry wastewater was a good idea for dealing with all the problems above At the present in Vietnam, studies on the recovery of N and P with different purposes have not been widely studied Therefore, from the practical requirements in Vietnam, the study aims to propose the topic "Study of recovery nutrients from poultry wastewater by modified biochar for soil application"

1.2 Research’s aim and content

1.2.1 Research’s aim

This study aims to fabricate the slow-release fertilizer from N and P in poultry wastewater by the modified biochar from crop residues and sludge

1.2.2 Research’s content

- To achieve this aim, this study has implemented the following contents as below: - Content 1: Biochar preparation and modification

- Content 2: Evaluating factors effect on synthetic wastewater - Content 3: Evaluating factors effect on poultry wastewater

- Content 4: Evaluating the slow-released ability of biochar fertilizer - Content 5: Soil application

1.3 Research’s subject and scope

1.3.1 Research’s subject

The research subjects of this study include:

- Ammonium and Phosphate from poultry wastewater - Synthetic wastewater

- Wastewater from small hennery - Plant for soil application

1.3.2 Research’s scope

This research takes place in environmental analysis laboratory, room 710, building H2, Ho Chi Minh University of Technology in second campus The experiment is proceeded in batch using wastewater from poultry farm

Time for research: from 3/2022 – 12/6/2023

1.4 Scientific contribution and prospective application

1.4.1 Scientific contribution

This study provides data on the ability to recover nutrients by adsorption method for the goal of slow-release fertilizer for plants with poultry wastewater At the same time, the topic is the basis for further research processes related to fertilizers for crop and cultivation

1.4.2 Prospective application

Taking advantage of nutrients from wastewater as fertilizer for crops helps farmers save some production costs, as well as protect the environment From there, it is possible to expand the production scale as well as reduce the costs of environmental treatment

CHAPTER 2 LITERATURE REVIEW

2.1 Overview of animal agriculture

The animal agriculture in Vietnam accounts for about 28% of the agricultural value and is an essential factor of the agricultural sector in Vietnam [3] The growth value of the animal agriculture industry is higher than the crop and service sectors, reaching an average value of 5.27% per year According to statistics in 2014 in our country, pork accounted for the majority of 73%, the rest was poultry meat 19%, beef 6%, and other types of buffalo meat accounted for 2% [1]

According to the General Statistics Office in 2020, poultry production will develop stably, although avian influenza still occurs in some areas Also in 2020, African fever happens but the total number of pigs in the country in 2020 still increase by 17% compared to 2019 [1] Over the next decade (2021-2030), FAO predicts that poultry meat production will continue to grow at a high rate and outpacing the growth of other meats By 2030, poultry meat will account for over 41% of all meat production and over 52% of all commercial meat The potential demand for meat consumption in Vietnam is mainly still high in the domestic market However, in the past decade consumption demand has tripled while meat production has only doubled Therefore, Vietnam had to import meat to meet its demand According to data from the General Statistics Office, in 2016 the total number of livestock farms in the country was 20869, in which many concentrated in provinces and cities such as Hanoi (3,189), Hung Yen (648), Vinh Phuc (1,007), Central Highlands (4,041), Thai Nguyen (800), Dong Nai (3,811) and Binh Duong (901) Our country has about 29.1 million pigs, about 8 million buffaloes, and 361.7 million poultry Which, livestock farming still accounts for about 65-70% of quantity and output From the number of heads of livestock and poultry, it can be converted to the amount of solid waste (manure, leftovers, or scattered food) that the herd of livestock and poultry wastes is about over 86

million tons, and about over 57 million cubic feet of liquid waste (urine, barn wash water, blanket yard)

2.2 Environmental affection

2.2.1 Polluted by solid waste [4], [5]

Solid waste in animal agriculture includes manure and animal feed (food for raising cattle, chicken, …) Food spillage, production packaging, hazardous waste

- Hazardous waste: In terms of care or vaccination activities for pigs and chickens a large amount of medical waste such as needles, cotton balls, medicine bottles, bottles is generated In addition, there are animal corpses due to illness or accidents, placenta during childbirth, these types of waste are listed as hazardous waste that needs to be handled separately

- Pig has dry manure and urine while fresh chicken manure consists of feces with a white paste mixed with the manure Manure is the residue of animal feed after passing through the digestive system, is not absorbed, or used up, and excreted from the body Feces contain a very small amount of garbage, fillers, and leftovers The chemical composition of feces includes cellulose, lignin, proteins, decomposed products of proteins, lipids, organic and inorganic acids Urine is the part of nutrients in animal feed that has been digested, dissolved in the blood after metabolism is excreted in the form of water The chemical composition of cattle urine is mainly urea, uric acid, hippuric acid, inorganic salts of K, Na, Ca, and Mg Poultry litter concludes thirteen types of plant nutrients like N, P, K, Na Mg, Cu, Zn, Fe, B, Cl, Mo, Mn, S and Ca

Table 2 1 Chemical composition of manure (following basic factor) [6], [7]

Cattle Ability for manure

Chemical composition (% weight)

production of 500 kg cattle

Volume

Fresh weight

(kg)

Solute Nitrogen Phosphorous C/N Potassium Calcium

Pigs 0.028 28.40 7.02 0.83 0.47 25

20-0.95

0.15-0.34

0.09-Table 2 2 Chemical position of broiler and turkey manure from South California [8]

Chicken (broiler litter) Turkey (grower litter)

environment, the water source will be polluted If waste is buried in the ground, it will pollute the soil as well as the odor will affect the surrounding air environment

2.2.2 Polluted by wastewater [9], [10]

Wastewater from the animal agriculture is mainly generated by the cleaning of the barn as well as the hygiene of the animals, consisting of urine, feces, and barn cleaning water The main components of polluting wastewater are organic matter, nitrogen and phosphorus, excess drug components, and pathogenic bacteria The waste is discharge directly into canals and rivers without any treatment, causing water pollution [9], [11]

Poultry wastewater typically contains more than 1% of total solids (TS) mainly organic and concentrations, chemical oxygen demand (COD), varies from less than 10 g/L to more than 100 g/L in harsh case There is also nitrogen and phosphorus in wastewater with a total nitrogen (TN) of 0.2–7.3 g-N/L and a total phosphorus (TP) concentration of about 0.2–0.5 g-P/L [9], [10]

The poultry litter should be covered if it is not using for land application in 1 or 2 days This will conserve the nitrogen contained in poultry manure, also decrease the nitrogen losses about 17 percent, odor, flies and leachate waste [8]

- Organic and inorganic substances

The organic substances that have not been assimilated and absorbed by cattle will be excreted in feces, urine, and other metabolic products Excess feed is also a source of organic pollution

In animal agriculture wastewater, organic compounds have nearly 70-80% including proteins, amino acids, fats, carbohydrates Most are easily degradable organic substances, enrich in nitrogen, phosphorus Inorganic substances account for 20-30% including sand, soil, salt, urea, ammonium, chloride salts, sulfate

Chemical compounds in feces and wastewater are easily decomposed Depending on anoxic or anaerobic conditions, the decomposition process produces different products such as amino acids, fatty acids, aldehydes, CO2, H2O, NH3, H2S If the decomposition process is present O2, the products formed will be CO2, H2O, NO2, NO3 If the decomposition process takes place in anoxic conditions, it will form products like CH4, N2, NH3, H2S, Indol, Scatol The gases produced by anaerobic and anoxic decomposition such as NH3, H2S … causing a stench in the farming area, which adversely affects the air environment

Wastewater is a complex mixture of beneficial and harmful microorganisms, including various types of parasite eggs, bacteria, and viruses that can cause diseases such as E coli, Salmonella, Shigella, and Proteus Arizona In healthy animals and humans, these microorganisms coexist in a symbiotic balance within the digestive tract However, when a pathological condition arises, such as diarrhea in cattle, the balance is disrupted, leading to an overgrowth of pathogenic bacteria that can outcompete the beneficial bacteria In cases of infectious diseases, the excretion of pathogenic bacteria in wastewater can pose a significant risk to the environment and other livestock

- Nitrogen and phosphorous [12], [13]

The nitrogen and phosphorous adsorption ability of cattle and poultry is not good, so they will be excreted in feces and urine after eating food containing nitrogen, and phosphorous Form of nitrogen in poultry feces is ammonium (N-NH4+), which can convert into NH3 at base pH level [8] Ammonia in poultry manure can be loosed from the feces surface whether it is storage or soil application Poultry wastewater often include high levels of nitrogen and a part of phosphorus Total nitrogen content in wastewater of cattle and poultry farm measured after biogas production is about from 100 to 594mg/l, phosphorus from 13.8 to 62 mg/L Nitrogen is excreted in urine and feces in the form of urea, then urea is quickly converted to NH3 according to the following equation:

(NH2)2CO + H2O NH4 + OH- + CO2 NH3 + CO2 + H2O

Microorganisms release the enzyme urease, which converts urea into ammonia From there, ammonia evaporates into the air, causing odors, affecting the surrounding environment N and P exist in water in the form of ammonium (NH4+), nitrate (NO3-) and phosphate (PO43-) A large amount of N and P are contained in animal agriculture wastewater, these two nutrients can cause eutrophication, affecting aquatic habitats

Table 2 3 Characteristics of poultry and swine wastewater

1341 - 1821 1602 ±

243

7719 5422 ±

3154-2282

-

7.3 – 8.6 8.2 ±

0.42

-

162.6 – 564 361 ±

215

-

7 – 17.1 12.3 ±

4.25

Celaya, Gto., Mexico[16]

8700

111.50

10.5-12.74

7.17-7.81

2.75-Tamilnadu, India [17]

1890

1300

1600-

Ontario, Canada

[14]

610 – 4635

(after biogas) [13]

582 307±9

192-0

264-789 463±12

7

188-821 373±12

3

-

421 259±7

106-4

712 536±8

355-9

122-492 318±84

-

Xuan Tho III, Dong Nai (after biogas)

3268

1664-5028

2561-3218

1700-8.1

7.23-471

512-594 13.8-62 -

Chuong My, Ha Noin

(after biogas) [19]

China (after

Jeongup, Korea [21]

TCOD 23821.5

10.5±0.5

8.02±0.11

3053.6±19.5

527.0±67.0

667.1±4.2

TCN 678

QCVN MT:2016/B

62-TNMT B

QCVN MT:2021/B

62-TNMT B DT

2.3 Animal agriculture wastewater treatment method

The composition of poultry farming wastewater is mostly organic, inorganic and micro-organisms that exist in the form of dissolved, dispersed, or larger in size Pollution characteristics of this wastewater are organic matter, nitrogen, phosphorus, and pathogenic microorganisms Depending on the production scale, the land fund used for treatment, economic conditions, the purpose of using waste, wastewater from common farm, the requirements of the receiving source, etc., appropriate treatment measures can be applied fit

2.3.1 Mechanical treatment method

The purpose is to separate solids, residues, and manure from the wastewater mixture by collecting and separating Using the screens to prevent garbage, preliminary settling tanks to remove coarse sediment, and reduce the volume of subsequent treatment works In addition, centrifugation or filtration methods can be used The concentration of suspended sediment in wastewater is quite high (about several thousand mg/l) and easy to settle, so it can be pre-settled before being transferred to the next treatment works After separation, the wastewater is put into the rear treatment works, and the separated solids can be composted to make fertilizer [22]

Mechanical methods include sedimentation and filtration, the resulting sludge can be utilized to produce fertilizer This method can help to reduce pathogens, such as Salmonella typhimurium, E coli, Streptococcus faecalis Depending on the type of membrane, it can separate the allowable substances However, this method have some negative points such as the high replacement cost of the membrane, not suitable when using too concentrated wastewater streams, need to be pre-filtered before passing through the membrane to avoid jam [23], [24]

The separate method can be applied by membrane technologies such as micro filter (MF), ultimate filter (UF), or nano filter (NF), and reverse osmosis (RO) The research of Kurama used RO for ion ammonia recovery performance 96.9% [25] The pig manures were treated by the RO and electrodialysis to produce composite (contain 13 g/L NH3-N) in the research of Mondor and cooperate [26]

2.3.2 Physicochemical treatment method

Chemical methods include flocculation, and sterilization Microorganisms and solids can be removed by sedimentation or filtration after flocculation Dissolved nutrients often collide together to form colloid and are removed by sedimentation Flexible operation, low cost for phosphorus removal However, there are by-products in the sterilization process such as trihalomethanes and chlorites The generated sludge requires an additional sludge treatment step, which is likely to contain heavy metals in the residual sludge It may contain toxins that have not been handled in time, which inhibit biological processes [22]

The cheapest and easiest for nitrogen and phosphate recovery was precipitation by chemical such as calcium, alumni, or iron [27] The condition of phosphate precipitation should be concerned was pH, alkalinity, and hardness Ammonium and phosphate could be removed by precipitation Magnesium ammonium phosphate (MgNH4PO4) or Potassium precipitation at pH > 8.0 (KNH4PO4) [28]

2.3.3 Biological processes

Biological method is an activated sludge system containing microorganisms under anaerobic, aerobic, or anoxic conditions depending on the nutritional requirements of microorganisms and the pollutant Biological methods help control odors, nitrogen levels in wastewater, organic decomposition products, inactivation, or removal of pathogens In addition, there are some disadvantages to note that microorganisms can be inhibited due to toxic compounds contained in wastewater (such as drug-resistant pathogens, heavy metals, and organic compounds), the process requires strict environmental control [22]

The biological treatment method has great advantages compared to other treatment methods in that it is low cost and high stability, especially the treatment efficiency is very high at a short retention time for wastewater containing high biodegradable organic matter Animal agriculture wastewater is identified as easily biodegradable because it contains mainly biodegradable organic compounds such as carbon hydrate (cellulose, hemicellulose, starch, sugar, dextrin ), Biological treatment of animal agriculture wastewater is a common method based on its feasibility and high economy [23], [24]

2.3.4 Brief conclusion

The above common animal agriculture wastewater treatment method could remove the pollutant such as nitrogen or phosphorous with medium to high performance However, each study has its own strengths and weaknesses For instance, wastewater needs to be treated first to avoid membrane clogging, biological methods need to ensure oxygen nutrition The controlled pH is suitable for microbial growth, the flocculation method has the major disadvantage of being costly in chemicals and requires measures to treat the generated sludge [22], [29] In addition, the purpose of this study is to recover the ammonium and phosphate for slow-release fertilizer Nitrogen and phosphorous common exist in the water at the form of NH4+, NO3- and PO43- which the main reason for eutrophication [30] Besides, phosphorus was a nonrenewable source which wasted and

presented in the wastewater [31] Therefore, this study is to recover ammonium and phosphate by the modified biochar as an adsorbent

2.4 Adsorbent material

2.4.1 Adsorption procedure

Adsorption was defined as a material that contains its liquid or gaseous surrounding on its solid surface C.W Scheele in 1773 had been seen the adsorption of gaseous on carbon, and Lowtiz in 1785 of the wood charcoals for odor and color removing However, the first one who came up with the term “adsorption”, was Kayser in 1881 [32] The basic procedure of adsorption followed by Kayser was the surface accumulation of the material [32]

At present, the adsorption was divided into two types of chemical or physical adsorption Physical adsorption was defined as the attraction between material surface and the adsorbed molecules in the physic way or the attractive forces van der Waals and the reversible in nature [32] In contrast, the attractive forces between material surface and molecules were chemical bonding instead of Van der Waal forces was known as chemical adsorption The bonding of chemicals was stronger than the physical ones, so it is hard to eliminate the species adsorbed on the material’s surface

2.4.2 Adsorbent materials

The high surface area was the main characteristic decided good or bad adsorbents The porous of adsorbent can be divided into three types of pores such as micropores, mesopores, macropores To remove pollutants the adsorbed need to have these characteristics high surface area, high porosity, and fast adsorption kinetics Some adsorbent that common in industry and others aim following:

- Alumina and Bauxite (Surface area 200 – 300 m2g-1) - Silica Gel (surface area 250 – 900 m2g-1)

- Zeolites and ion exchange resin (about 700 m2g-1) - Activated carbon (500 – 2000 m2g-1)

Fig 2.1 Diagram for removal and generation solid liquid pollutants [32]

Fig 2.1 shows the low-cost adsorbent was generated and using by the solid liquid pollutants To reduce the price of adsorbent material, the low – cost adsorbent was investigated The low – adsorbent can be classified by their availability (natural materials, industrial/agricultural/domestic wastes or by product, …) or on nature (inorganic and organic) The low – cost adsorbent after wastewater treatment which can become a beneficial by product such as biochar [32]

2.5 Biochar

2.5.1 Definitions

Biochar was defined as enrich in carbon with the nature biomass such as wood, manures, or leaves in close container without or less oxygen by Lehmann and Joseph In addition, biochar was also introduced as a porous carbonaceous solid in the lack of oxygen atmosphere which could store carbon in a long time Biochar could be utilized by any kind of biomass such as animals waste, crop residues or sewage sludge [33]

Fig 2.2 The image of biochar

2.5.2 Biochar properties [34]

The carbonaceous solid is the main product of biochar manufacture The evaporation water and volatile component leads to the high content of fixed carbon in the solid To get the higher carbon content up to 95%, the temperature may reach near to 1000oC However, this temperature is just suitable with the wood feedstock instead of the crop residues with the lower ash melting temperature (not > 700oC)

Besides the process factor, the characteristics of biomass feedstock can affect the properties of last material There are three organic compound is mostly contained in the biomass lignin, cellulose, and hemicellulose Hemicellulose decomposed at the temperature of 220 – 315oC, known as a polysaccharide with branches Cellulose is not reactive as the hemicellulose and decomposed at temperature of 280 – 400oC With the large function group in the complex three – dimensional macromolecule structure, lignin

has the decomposition temperature range 200 – 900oC Based on the decomposition and properties of three organic compound, the process conditions should be design properly for the product’s aim In addition, animal manure or sewage sludge was not researched about the present of three kind of organic compound in them; therefore, they must be classified in other types of biomasses

❖ Structural compound

The temperature range of 250oC – 350oC is the most active range in which nearly total the hemicellulose decomposes and part of cellulose and lignin decomposes leads to transformation in the characteristics of the material With the time of pyrolysis being 5 min and the temperature of larger than 400oC, it is seen that the decomposition of almost holocellulose (mixture of cellulose, hemicellulose, and water-insoluble carbohydrate) Furthermore, with a short pyrolysis time at 2 min, a partial of holocellulose is decomposed, with higher temperature > 650oC, mostly all holocellulose converted whether short time or not

❖ Porosity and density

When the gases are released from the structure of the material, a carbon frame is formed during the pyrolysis process The charcoal in a unit per unit volume of biochar is lower while the porosity of biochar is higher The porosity of the last product can achieve 72% with a temperature of 850oC for wood Moreover, if the biomass is grass, the porosity can reach 80% at the temperature range 350 – 700oC

Porous are divided into three groups: micropore, mesopores, and macropores Micropores are the group with the largest adsorption energy; molecular size, active radius site less than 2 nm, pore volume from 0.15 to 0.7 cm3/g, a specific surface area of about 95% of the total surface area of biochar The adsorption in these pores occurs by a pore volume-filling mechanism and no capillary condensation occurs The mesopore, also known as the transport hole, has an active radius site from 2 nm to 50 nm, and its volume

is usually from 0.1 to 0.2 cm3/g Macropores are not significant in the adsorption of biochar because they have very small surface areas (<0.5 m2/g) They have an active radius site greater than 50 nm and are typically in the 500 - 2000 nm range with pore volumes from 0.2 to 0.4 cm3/g This group of pores acts as a channel for the adsorbed substance to enter the micropore and the mesopore

❖ Surface area

The surface area is the result of the devolatilize gases during the pyrolysis process A biochar’s surface area relates to other properties such as ion exchange capacity, water capacity holding BET analysis is the common technique for the surface area of biochar determination At a temperature range of 800 – 1000oC, the surface area of biochar is decreased after the initial increase With the wood biomass, the surface area grows by 373.5 m2/g at the temperature from 450oC to 750oC However, the surface area goes down to 3.5 m2/g at 1000oC

❖ Hydrophobic

The higher the pyrolysis temperature, the higher ability of hydrophobic biochar caused the polar functional groups to be eliminated and risen of aromatic Hydrophilic compounds are a polar and strong attraction with the water while hydrophobic substances are nonpolar The hydrophobic surface may not allow the water adsorbed in the pore structure Some researchers believed that the high temperature helps the surface of biochar is hydrophobic while the others did not get the same results at the temperature above 500oC The aliphatic functional groups, eliminated at the 400oC – 500oC, are related to the hydrophobic biochar The destruction of these functional groups leads to the changes from hydrophilic to hydrophobic biochar in the torrefaction process at > 300oC On the other hand, the hydrophilic char may occur if the temperature is higher than 500oC

❖ Cation exchange capacity

The amount of exchangeable cation that a material can hold is the definition of cation exchange capacity The cation can be adsorbed on the surface site of biochar due to the negative charge surface The cation exchange capacity is based on the surface area, surface charges, and functional group of biochar At the lower process temperature and higher pH level, the amount of exchangeable cation of biochar is higher The cation exchange capacity of wood and grass feedstocks at pH level (1.5 – 7.5) was the maximum at 250oC

2.5.3 Application of biochar

The application of biochar into the soil can change the physical characteristics of soil like structure, texture, pore distribution size, … The porosity of biochar may affect the soil pore network The size of biochar, distribution, the connection of pore, the mechanical strength is also effective factor of the soil properties These components may inhibit or improve the overall soil porosity [35]

Biochar added into the soil may affect the physical and chemical properties of soil The benefits in agriculture of biochar are nutrition conservation or improved water Based on the large surface area of biochar, it connects to the water-holding ability of soil Biochar can interact with the soil organic matter, minerals or microorganisms depending on the surface charge of biochar Old biochar (Aged biochar) which is high at cation exchange capacity improves the interaction between biochar and soil organic matter, or minerals [35] The cation exchange capacity of soils prevents the leaching of nutrient to environment, helps the plant adsorbed the nutrient CEC change of the biochar by the weather or soil activity, aged, or moves in soil has not been studied yet At the neutral pH, anion is bad connected with soil so biochar application at pH 3.5 improve anion exchange capacity In addition to providing necessary nutrients, in biochar, there are humid acids containing hormones that can plant growth; can absorb ammonium from the soil solution, helping to reduce the amount of nitrogen lost by seeping into the soil; capable of reducing ammonia volatilization; improve soil quality from 80% to 220%, increase nutrient

absorption capacity of plants and prevent soil erosion, especially soil in unstable terrain …[36] Moreover, biochar can remove nitrate, ammonium, or phosphate in wastewater Furthermore, biochar helps to deodorize and disinfect common farms by using biochar in combination with microbial products to make bio-mats for poultry farms; Biochar also can absorb CO2 from the of plants to store and create others form of energy This property of biochar is a revolution of environmental protection, minimizing the effects of greenhouse gases [36]

2.5.4 Biochar production

The first kiln includes pits (decrease heat losses, air controlling) which is a simple and low-cost technique Kiln simply makes by concrete, clay, or metal to produced charcoal Kiln lately is improved to optimization the biochar mass yield from batch mode to continuous mode In traditionally, charcoal manufacturing has three steps with three types of smoke as following:

- Drying step with white smoke - Pyrolysis step with yellow smoke - Finished step with blue smoke

Fig 2.3 (a) Mound kiln; (b) Pit Kiln

Fig 2.2 describe shape a typical mound and large pit kiln Volume of a small pit kiln is about one m3 while volume of large one can up to 30 m3 or bigger Mound kiln is

(b) (a)

not built underground like pit, outside the mound is a layer of earth for controlling air and heat losses As describes in fig 2.2 (a), mound kiln has diameter of 4 m, height of 1 m or 1.5 m [36]

Fig 2.4 (a) Brick Kiln; (b) Metal Kiln

Fig 2.3 shows shape of brick kiln and metal kiln Brick kiln is a low – cost construction which produces good quality and high amount of charcoal rather than old pit and mound kiln Charcoal manufacturing process (carbonization stage) is conducted by the worker over 6 – 7 days or more [36] The inside diameter of brick kiln is about 5 – 7 meters, the outside height of three meter The metal kiln utilizes widely around the world in 1960s Metal kiln eight channels for ventilation and 4 channels for smokestack which can controlled air emission easily [36] The charcoal process occurs in three days which is shorter than brick kiln Lately, the concrete kiln and hearth kiln is invented and have more advantage rather than the older kiln The charcoal yield of concrete kiln is about 16t through 3 weeks cycle To calculate the char yield from the kiln, the following equation is applied:

The biochar manufacturing is simply the process that convert biomass into biochar in pyrolysis conditions without oxygen However, it is not only the last product of pyrolysis process biochar but also the gas and condensable vapors The condition of pyrolysis and properties of biomass decided the percentage of gas, condensable vapors, or char As shown in the Table 2.4 about the percentage of last product following different pyrolysis conditions

Table 2.4 Product (dry %) with different types of pyrolysis [36]

(%) Char (%) Gas (%)

Fast Moderate temperature ~ 500°C

Short vapor residence time ~ 1sec 75 12 13

Moderate

Moderate temperature ~ 500°C Moderate vapor residence time ~ 10–20sec

Slow

Moderate temperature ~ 500°C Very long vapor residence time ~ 5–30min

generally concerns (i) increasing the surface area and porosity; (ii) enhancing the surface [37]

Fig 2.5 Loaded technique of biochar for different emphases [37]

Chemical modification can be achieved through both one-step and two-step processes One-step modification involves carbonization in the presence of chemical agents, while two-step modification first involves carbonization of the raw material, followed by modification of the resulting product through mixing with a chemical agent or pretreatment with a precursor prior to carbonization Although these processing methods generate additional costs, the benefits in terms of enhanced product features make them worthwhile [21, 22] The choice of modifying agent used depends on the specific pollution criteria to be treated

- Chemical modification

The process of chemical treatment usually involves impregnating biochar with acids or bases Alternatively, the surface functional groups of biochar can be transformed

intentionally by oxidation using agents such as hydrogen peroxide (H2O2), potassium permanganate (KMnO4), ammonium persulfate (NH4)2S2O8, and ozone (O3), as shown in a previous study [23] Strong acid agents like phosphoric acid H3PO4, sulfuric acid H2SO4, nitric acid HNO3, and hydrochloric acid HCl have been studied for their ability to oxidize pollutants in water, which can increase the surface acidity and alter the porous structure of biochar

Among these agents, H3PO4 is one of the most used for chemical modification as it is more environmentally friendly than other corrosive and hazardous reactants like ZnCl2

[24] Degradable H3PO4 can yield lignocellulose, aliphatic, and aromatized materials while forming cross-bridges between phosphate and polyphosphate, thereby avoiding shrinkage or loss of porosity during the development of porosity [25] Other inorganic acids, such as HNO3, H2SO4, and HCl, have also been widely used to transform biochar Oxidation by HNO3 treatment has been shown to cause degradation of the micropore wall due to its corrosive nature, resulting in a decrease in the total surface area Similarly, treatment with H2SO4 reduced the porosity of biochar by 10 to 40% and improved the size distribution of heterogeneous pores [26] Dehydration of H2SO4 during pyrolysis can be detrimental to surface area growth due to excess water vapor migration towards the surface structure [27] Organic acids such as oxalic acid C2H2O4 can enhance the uptake of pollutants through ligand and proton promotion processes [28] Overall, strong acid treatment is known to introduce acidic functional groups like amino and carboxylic groups to the surface of biochar, thereby enriching metal affinity and absorption through cation exchange and surface complexation with these additional active sites

The use of potassium hydroxide (KOH) and sodium hydroxide (NaOH) in the alkaline activation of biochar can increase its oxygen content and surface basicity This process also dissolves ash and condensed organic matter, such as lignin and cellulose, which facilitates further conditioning Two-stage activation with KOH has been found to generate a larger surface area with additional surface hydroxyl groups In fact, extremely

high surface areas have been reported for biochar that has been activated with KOH or NaOH During activation, potassium species (K2O, K2CO3) can form due to the intercalation of K+ in the crystal layer, resulting in a condensed carbon structure These species can diffuse into the internal structure of the biochar micropore matrix, widening existing pores and creating new ones Overall, the use of KOH and NaOH in alkaline activation can significantly improve the properties of biochar, making it more effective in a variety of applications

The concept of mineral oxide impregnation involves preparing modified biochar by impregnating minerals with biochar Clay minerals have been widely used to remove contaminants due to their cation exchange capacity (CEC), surface charge, mineral structure, and composition Montmorillonite, gibbsite, and kaolinite are among the most used clay minerals, as well as iron oxide, which is a low-cost absorbent In most cases, the surface area of the clay biochar composite is lower than that of unmodified biochar because clay particles tend to clog the pores However, the integrated performance of biochar and clay for pollutant removal can significantly increase the contaminant absorption capacity As a result, the reduction in surface area does not lead to a reduction in absorbance efficiency [21]

- Physical modification

In general, physical, or mechanical methods of transformation are often simple and economically feasible, but less efficient than chemical methods Physical modification processes involve the use of oxidizing agents such as carbon dioxide (CO2), steam, and air, without the addition of any chemicals

Steam activation is a process that can upgrade conventional biochar to activated biochar, which has improved carbon structure and high surface area The process involves two stages In the first stage, the biochar undergoes pyrolysis reactions in the absence of oxygen at moderate temperatures ranging from 400°C to 800°C In the second stage, the