Proceedings of the 4 th International Conference on Civil Engineering for Sustainable Development (ICCESD 2018), 9~11 February 2018, KUET, Khulna, Bangladesh (ISBN-978-984-34-3502-6) ICCESD-2018-4983-1 INVESTIGATION OF OPTIMUM INITIAL MOISTURE CONTENT OF CO- COMPOSTING PROCESS IN KHULNA CITY OF BANGLADESH Md. Alamin 1 and Quazi Hamidul Bari 2 1 Post-graduate Student, Department of Civil Engineering, Khulna University of Engineering & Technology, Bangladesh,e-mail: alamin081@gmail.com 2 Professor, Department of Civil Engineering, Khulna University of Engineering & Technology, Bangladesh, e-mail: qhbari@ce.kuet.ac.bd ABSTRACT Composting is the biological degradation of highly concentrated biodegradable organic wastes in the presence of oxygen (aerobic decomposition) to carbon dioxide and water, whereby the biologically generated waste heat is sufficient to raise the temperature of the composting mass in the thermophilic range (50 o C to 65 o C). In this study, temperature variation and Volatile Solids reduction of the composting process in different initial moisture content were investigated. Also determine the optimum initial moisture content in co-composting process. Organic solid waste was prepared according to waste proportion vegetable wastes: food wastes: waste paper: sawdust as 40:35:10:15. Organic solid wastes (OSW) and faecal sludge (FS) was mixed ratio 90:10 (OSW: FS). Total seven initial moisture content of organic solid wastes and faecal sludge were taken such as 20%, 30%, 40%, 50%, 60%, 70% and 80%. To investigate the effect of initial moisture content on volatile solids (VS) degradation and temperature parameters for total 14 reactors were used. Composting tests were performed in 30 days duration every initial moisture content. Temperatures at composting mass were continuously monitored. Maximum temperature of composting process was 55 o C to 65 o C which raised within 7 days in the moisture range between 50% and 70%. The area under the temperature curve in o C.h was highest in the initial moisture range between 50 and 70%. It should be noted that a higher value of the area under the temperature curve indicates higher heat production and thereby higher VS degradation. For detemination of optimum moisture content, the area under the temperature curve in o C.h and %VS reduction was highest in the initial moisture content range between 55% and 70%. VS reduction sharply decreased at an initial moisture content below 30 to 40%. Keywords: Organic solid waste (OSW), Temperature, Co-composting, Moisture content and volatile solids reduction 1. INTRODUCTION Khulna is the country’s third largest city in Bangladesh and has been known as an industrial city with a port. The whole city area is only 2.5 meters above the mean sea level. Khulna has a history of about one hundred years. Composting is the best option for solid waste management. However, composting offers a cost-effective sustainable solution for the biodegradable organic wastes. This is a very effective process for recovering waste materials and for minimizing environmental emission by stabilizing the organic wastes in the shortest period of time. In practice, the main biological process applied for solid wastes is composting (Haug, 1993). Although this biological decomposition can take place under aerobic or anaerobic conditions, composting is mainly considered as anaerobic process. Anaerobic composting has higher odor potential because of the nature of many intermediate metabolites (Haug 1993), whereas aerobic composting minimizes the potential of nuisance odors (Metcalf & Eddy,1979). The decomposition rate in anaerobic composting is also very slow.The use of organic solid waste has a long history mainly in areas of the world. The biodegradable portion could be managed either by recycling and recovering through biological treatment, or disposal to landfills. Solutions for effective and sustainable Faecal Sludge Management (FSM) presents a significant global need. FSM is a relatively new topic, however, it is developing rapidly and gaining acknowledgement. FSM can be managed together with composting process and the find process is usually named as Co-composting.