THAI NGUYEN UNIVERSITY UNIVERSITY OF AGRICULTURAL AND FORESTRY DAM HA LUONG THANH BIOMETHANE POTENTIAL TEST FOR RAPID EVALUATION OF ANAEROBIC DIGESTION OF SEWAGE SLUDGE FROM MULTIPLE MATERIALS FOR A PROPOSED LARGE-SCALE DIGESTER BACHELOR THESIS Study Mode: Full-time Major: Environmental Science and Management Faculty: International Training and Development Center Batch: 2012 - 2016 Thai Nguyen, 2016 DOCUMENTATION PAGE WITH ABSTRACT Thai Nguyen University of Agriculture and Forestry Degree Program Bachelor of environmental Science and Management Student name Dam Ha Luong Thanh Student ID DTN1353110232 Biomethane potential test for rapid evaluation of anaerobic digestion Thesis Tiltle of sewage sludge from multiple materials for a proposed large-scale digester Assoc. Nguyen The Hung, Thai Nguyen University of Supervisor Agriculture and Forestry, Vietnam Abstract This paper examines the biomethane potential from organic wastes. The biomethane potential test is used to assess the suitability of different substrates for biomethane production. A methodology for accurately estimating the biomethane potential from multiple heterogeneous organic waste substrates is sought.
Three main substrates were identified as possible substrates for biogas production, namely: pig manure, food waste, and beer processing waste. The biomethane potential of these substrates ranged from as low as 82 L CH4 kgVS-1 for beer processing waste to as high as 112 L CH4 kgVS-1 for food waste treatment. The objective of the paper is to suggest an optimum substrate mix in terms of biomethane yield per unit substrate for the proposed anaerobic digester. This should maximise the yield of biomethane per capital investment.
Pig manure displayed the highest biomethane yield (13 Lkg-1) followed by food waste (3 Lkg-1) and beer processing waste (2 Lkg-1). biomethane potential test, anaerobic digestion, sewage sludge, Keywords biogas Number of papers 40 pages Date of submission: 21/09/2016 Supervisor’s signature: ii ACKNOWLEDGEMENTS Completion of my Bachelor Thesis at Thai Nguyen University of Agriculture and Forestry has not been achieved by my efforts alone, but memorably contributed by many wonderful people to whom I must express my great thanks. My sincere gratitude is offered to Assoc. Nguyen The Hung who gave me a precious opportunity to carry out this study along with his enthusiastic support throughout my thesis with his patience and knowledge whilst allowing me the room to work in my own way.
I attribute the level of my Bachelor degree to his encouragement and effort. A word of thanks must be also recorded to Ms. Anurag Deo and Ms. Mette Axelsson Bjerg from Linköping University for their commitment and companionship as teammates throughout this study, especially during the time they constructed their Master Thesis of Biogas plant in Thai Nguyen Agriculture and Forestry (TUAF).
I would also like to offer special thanks to Mr. Duong Manh Cuong (MS), lecturer in Faculty of Biotechnology and Food Technology, TUAF for his suggestions and assistance in setting up my experiment. I am also grateful to all laboratory technicians and managers, Mrs. Hoan, Mrs, Phuong, and Mr.
Lam from Faculty of Biotechnology and Food Technology, TUAF for their whole-hearted help during the time I carry out my experiment. To my family, my heartfelt thanks are expressed for their unconditional love and belief. DAM HA LUONG THANH iii TABLE OF CONTENS List of figures. vi List of table.
vii List of abbreviation. viii PART I: INTRODUCTION .3 PART II: LITERATURE REVIEW .1 Type of sewage sludge .2 Component of sewage sludge .2 Anaerobic sludge digestion .1 Fundamentals of anaerobic digestion .2 Current status of anaerobic digestion process .3 Factors influencing the anaerobic digestion process. Nutrient requirements for anaerobic digestion .5 Anaerobic digestion in sewage sludge treatment .20 PART III: MATERIALS AND METHODS .1 Biomethane potential test equipment .1 Analyzing total solid (TS), volatile solid (VS) and organic loading rate (OLR) .3 Biomethane Potential (BMP) experiment .1 Characteristics of inoculum and materials .3 Methane potential per mass of substrate. DISCUSSION AND CONCLUSION .34 v LIST OF FIGURES Figure 1.
Anaerobic digestion process of organic maters (Thanh, N. Factors influencing AD performance. Analysimg CH4 concentration. Monitoring biogas production.
Methane production curve of materials .30 vi LIST OF TABLE Table 1. Typical constituents of different types of sludge. Summarises the optimal concentration and effects of these nutrients in the anaerobic digestion process. Advantages and disadvantages of anaerobic sludge digestion.
Preparation of nutrient solution. Preparation of sodium hydrate solution. Characteristics of inoculum and materials. Bio-methane potential of substrates.
Weighted average methane potential per kg of substrate .30 vii LIST OF ABBREVIATION AD : Anaerobic digestion BMP : Biomethane potential test ORL : Organic loading rate TS : Total solids VFAs : Volatile fatty acids VS : Volatile solids Ww : Wet weight WWTs : Wastewater treatment WWTPs : Wastewater treatment plans viii PART I: INTRODUCTION 1. Research rationale In recent years, there are several techniques for the treatment and management of sewage sludge, including landfill, incineration, composting, and anaerobic digestion (AD) process. Among them, AD is the most commonly used technique since biogas, which is a valuable form of bio-energy, can be extracted from sewage waste. Anaerobic digestion is a process by which organic materials are naturally broken down into biogas and bio-fertilizer.
In this process involving several sequential biochemical stages, many different microorganisms participate in a complex web of interacting processes which result in the decomposition of complex organic compounds as carbohydrates, fats and proteins to the final products as methane and carbon dioxide. This process occurs naturally in many environments with limited access to oxygen, for example in bogs and marshes, rice paddies and in the stomach of ruminants, such as cows. Besides, it happens in the absent of oxygen naturally, or in sealed, free-oxygen tanks called anaerobic digesters. AD of solid organic waste such as bio-waste, sludge, cattle manure, energy crops, and other biomasses, for bio-energy production is widely applied technologies.
The production of biogas in AD offers several advantages over the other alternatives. These include biogas production, nutrient recovery, and reduction of waste organic content and pathogen agents. Sewage sludge can be described as a byproduct mixture of solid and water from wastewater treatment (CIWEM, 1995). By applying several different treatment 1 processes, the resulting sewage sludge types extremely differ in their characteristics.
Constituents of sewage sludge regarding to carbonhydrate, proteins, lipids are highly depended on their origin. The presence of significant concentration of nitrogen, phosphorus, and potassium in sewage sludge make it possible for fertilizing soil because these elements are essential for plant growth. Anaerobic digestion instability is resulted from the fluctuation in organic loading rate, heterogeneity of waste or excessive inhibitors. Towards improving AD performance in biogas production and accelerating the microbial activities for higher quality of bio- solids, several environmental conditions should be meticulously controlled.
Additionally, various studied have demonstrated that hydrolysis phase is a rate- limiting stage, and seriously impacts on the performance of AD. At present, end-users in Vietnam, often have difficulties in controlling the technology efficiently, due to poor management competence (Jiang et al. This leads to production being inadequate in periods of high demand in low temperature regions during winter, and excessive during periods of high temperature and high production of excreta (Cu et al. There is thus a need to improve knowledge about biogas production potential using local biomass, in order to develop digesters adapted to the local environment and individual management schemes, thus ensuring production of the gas needed for cooking, heating and light (Vu et al., 2007; Cu et al.
Hence, there is an associated need to review, develop and validate methods to assess biogas production which can be used in laboratories with limited access to analytical instruments. Research carried out at laboratories in regions with limited access to high- 2 tech instruments must be of international standard, so as to ensure useful results and contribute to progress in development of the technology.2 Research’s objectives This paper aims to assess and screen potential substrates from three major waste streams for a proposed anaerobic digestion facility using the biochemical methane potential (BMP) test which can be carried out in simple laboratories. The BMP test is also used to assess the level of variability of biomethane potential (methane concentration in biogas) within the waste streams by using Dr. Einhorn’s fermentation saccharometer with dilution tube and absorption of CO2 in alkaline liquid (7M NaOH).
The objective is to recognize substrates with a high methane production per unit mass in lab-scale with limited access to analytical equipment, which will lead to an economic digester design in future.3 Research questions This study is operated to investigate these following issues: o How much biogas can be produced from the substrates? o What is methane potential of the substrates? 1.4 Limitation The increasing demand of renewable source of energy and quality of bio-solids has determined as a great deal to formulate the feasible treatment processes applied in WWTPs. In addition to sewage sludge stabilization, AD has been known to produce biogas, which is renewable fuel. Using organic materials is expected to enhance the efficiency of anaerobic digesters. Furthermore, a more comprehensive understanding 3 of key physiochemical properties of the substrate, operational conditions, and biogas potential is of great necessary prior to any large-scale opperations.
The BMP assay is designed to provide ideal anaerobic conditions and prevent any form of biochemical inhibition. To ensure this, three important conditions should be met throughout the BMP assay (Labatut, et al, 2010): (1) appropriate microbial community, enzyme pool, and nutrients are present; (2) environmental conditions are optimal; and (3) substrate and intermediate product concentrations are well below inhibitory/toxic levels. BMP results should be limited to a relative interpretation of the substrate’s methane potential, and not for an absolute estimation of daily biomethane yields or the overall performance and stability of large-scale digesters, it is best suited when used to elucidate what types of substrates, from an array of potential substrates, have the highest biomethane potential. 4 PART II: LITERATURE REVIEW This chapter provides an overview of the current knowledge regarding bio-methane potential test, including anaerobic digestion of sludge sewage and other organic waste materials.
The AD process is firstly presented and discussed. This is followed by a comprehensive review of CH4 production by anaerobically digesting sewage sludge with other substrates.1 Sewage sludge In the effort of improve effluent quality, waste water treatments (WWTs) are built and upgraded. While these plants can produce high effluent quality, sludge disposal remains underlying issues. These include the expensive cost of sludge treatment, which makes up more than 50% of total WWTs cost (Rulkens, W., 2007), and potential risks associated with the sludge disposal for the environment and human health.
Sewage sludge is a mixture of solids and semi-solid removed from the liquid stream of WWPs. A more restricted definition is “a residual solid from sewage plants treating domestic and urban waste water and from other sewage plants treating waste water of a composition similar to domestic and urban waste water” 2.1 Type of sewage sludge To assess options for sludge treatment and disposal, it is necessary to investigate different kind of sludge and origins. A typical sewage treatment plants includes primary, secondary, and tertiary processes (Fytili, D. 5 Primary sludge is collected from primary treatment process containing high total solids (TS) content.
The characteristics of primary sludge vary considerably depending on the initial compositions of wastewater, the efficiency of primary sedimentation and the usage of chemicals in sedimentation (Guyer, J. Primary sludge may contain oil, grease, vegetable materials, paper, faecal materials, sanitary and medical waste, kitchen waste. Treatment process such as activated sludge process, or rotating biological contactors results in humus sludge or biological sludge (Arnaiz, C. Humus sludge is the settled product from soluble waste in the primary effluent.
This is a mixture of microorganism: sloughed bacteria and fungus under living or dead remains. Humus sludge has earthly smell and color of dark brown. Humus sludge from biological aerated filters and their variation, which have different types of biological media, share certain characteristics with activated sludge.