An evaluation of pre-concentration technologies for domestic sewage to enhance the performance of anaerobic degestion | |
| Author | Rathnayake, Thusitha Dilruwan Wijewardhana |
| Call Number | AIT Thesis no.EV-17-29 |
| Subject(s) | Sewage--Purification--Anaerobic treatment Sewage--Treatment--Evaluation |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. EV-17-29 |
| Abstract | This study compares the performance of three different pre-concentration technologies; woven fiber microfiltration (WFMF), tube settler (TSET) and conical membrane tank (CMT) that can apply to, concentrate the domestic sewage prior to the anaerobic treatment. The main goal of the pre-concentration is to concentrate as much as possible of the wastewater organic matters in a separate stream, which can later be used for energy recovery. The pre-concentration performance was evaluated in terms of chemical oxygen demand (COD), suspended solid (TSS) concentration and the energy consumption. WFMF was able to concentrate 21 to 24.2 g COD/ m³. d of COD, while CMT had 17.5 to 19.7 g COD/ m³. d. TSET indicated that the lower COD pre-concentration performance with 0.005 m/h and 0.01 m/h loading rates as 1.8 and 2.6 g COD/ m³. d. In terms of TSS accumulation, WFMF and CMT resulted in more than 90% while TSET had 63%. In terms of the effluent quality, the WFMF was able to remove 68% of COD while CMT has 77%. This could have a potential of reuse application of the permeate water for agricultural purpose. Thus, the WFMF was found to perform better among the three technologies in terms of domestic sewage pre-concentration. Once found to be the best performing technology as WFMF 7.5 LMH flux, it was continued for pre-concentrating the domestic sewage. Concentrated domestic sewage was used as a feed water to the anaerobic membrane bioreactor (AnMBR) and the performance was evaluated in terms of biogas generation, methane content of the biogas and the removal efficiencies of TSS, BOD and COD. The AnMBR was able to generate biogas 28 mL/g COD with concentrated domestic sewage. 38 % of methane content was found to be in the biogas for concentrated domestic sewage at 3.2 kg COD/m³.d loading rate. TSS, BOD, and COD removal efficiencies were 99, 67, and 71% for the AnMBR process, respectively. Finally, this research proved that the capturing of solid fraction from the domestic sewage can lead to generate higher COD concentrations that can be effectively used in the anaerobic digestion process. Furthermore, this research discussed the common unit approach on different pre-concentration technology comparison and importance of the sludge cone volume for the mass balance approach. Moreover, this concept helps to reduce the anaerobic reactor volume by concentrating the domestic sewage. |
| Year | 2017 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Environmental Engineering (EV) |
| Chairperson(s) | Visvanathan, C.; |
| Examination Committee(s) | Annachhatre, Ajit P.;Thammarat Koottatep; |
| Scholarship Donor(s) | Bill & Melinda Gates Foundation / Sustainable Decentralized Wastewater Management in Developing Countries Project;Asian Institute of Technology Fellowship; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2017 |