Thesis (M.Sc.) - Asian Institute of Technology - UNESCO-IHE, 2015

A thesis submitted in partial fulfillment of the requirements for the Degree of Master of Science in Urban Water Engineering and Management jointly offered by the Asian Institute of Technology, Thailand and UNESCO-IHE, The Netherlands

In Thailand, 84% of the sanitation facilities are cesspool systems, but these are normally associated with environmental problems and to counter that, a Cess - to - Fit model is proposed The aim of this study was to investigate the performance of different support media for the Cess - to - Fit model with respect to pollutant removal at HRT of 1, 2 and 3 days in the ambient lab conditions as well as in real site conditions. Four identical reactors having effective volume of 90.50 L were installed with three diff erent support media, PVC Pall rings, Plastic Tubes, Plastic Strips and one as the Control. The media occupied volume for each reactors were 35.16 L . The synthetic blackwater made by mixing faecal sludge and AIT wastewater was fed three times in a day as in f luent to the reactors. 90.50 L/day, 45.25 L/day and 30.16 L /day flow was fed to each reactor for 33, 21 and 20 days respectively. Three similar reactors, having 102.50 L effective volume. Consisting the PVC Pall rings, 148 lit., consisting the Plastic tu bes and 108 lit. Consisting the plastic strips were installed in three different cesspools of the households situated in Pathumthani province of Thailand for 50 days. The quantity of support media were kept exactly the same as in the lab scale reactor. Th e grab samples analyzed for all the lab scale reactor for the operational period of 71 days achieved more than 90% of TCOD and TSS removal efficiency. However, when TCOD and TSS removal along the media zone were analyzed, the plastic tubes performed least in terms of TCOD and TSS removal. All the lab scale reactors showed less impact on nutrient removal. The field reactors with the PVC Pall rings, the Plastic strips and the plastic tubes showed average TCOD removal efficiency of 67%, 49% and 39 % respective ly in 50 days of operation. In case of TSS removal efficiency the reactor with PVC pall rings attained more than 90% and other two attained around 80% within the same time period. As in the lab scale study the nutrients removal remained inefficient for rea l site conditions as well . According the lab and field study the PV C Pall rings showed superior performance. The study for lab reactors showed that the concentration of SCOD in influent and effluent remain almost same but TCOD removal efficiency was above 90%. It shows that the settling of the suspended solids was the major phenomena to remove the TCOD and TSS from the influent for the study period. The s upport media inside the Cess - to - Fit model enhanced the solid entrapment thus increasing the pollutant removal from the influent blackwater . A further study is recommended for the TCOD, TSS and nutrients removal by attached biofilm on the surfaces of supp ort media. Clogging is the associated problem with the Cess - to - Fit model, further study is necessary to investigate the clogging phenomena in Cess - to - Fit model for different types of toilets.