Research
Anaerobic Co-Digestion of Municipal Sewage Sludge with Cow Dung at Different Ratio
A large amount of sewage sludge is produced through the sewerage system in Bangladesh. A laboratory scale research work was carried out to find the potential of sewage sludge as a source of renewable Bio-Energy. This paper presents the output results of the research work which was carried out to find out the appropriate technology for biogas generation from co-digestion of sewage sludge & cow dung. The study deals with usage of different proportion of sewage sludge, cow dung and domestic sewage for four trials carrying 6% total solid concentration. For all the experiments, sewage and domestic sludge were mixed in 1:1 ratio. Anaerobic digestion was performed for 60 days at room temperature 30±4 ºC. The pH of the slurry was maintained by the system itself. The inoculum was familiarized with cow dung in the same atmosphere taken for the study and sufficient active biomass was present. It was observed in the research that, when sewage sludge mixed with other co-substrate, the significant increase in gas yield was remarkable. The performances of the reactors were analyzed on the basis of gas yield and methane yield. On the basis of the analysis of the performance of the reactors, it was found that; Trial-2 reactor containing 25% cow dung and 75% municipal sewage sludge and domestic sewage, on total solid (6% TS) of slurry gives optimum result in terms of total gas yield and methane yield (72%). Standards of Trial-2 might choose as an optimum condition for gas generation from municipal sewage sludge.
Pile Load Testing and Determining Bearing Capacity of Cast in Situ Pile: A Case Study
Piles are designed to transfer the load of superstructure to the deeper harder soil strata crossing the upper weaker strata of soil. Cast in situ piles are usually designed by many analyses and using many empirical formulas. But due to a great degree of prevailing uncertainties of subsoil behavior, variation of strata in the same site, diversity in the procedure of construction applied at site, piles are needed to be tested to double or so of design load to verify the conformity with that design load obtained by static design calculation. A case study of load test on a pile of 600mm diameter & length of 35.250m was conducted through ASTM D 1143-81 method. The test load data were collected and converted into graphical forms. The results were interpreted through load-settlement curves applying various methods for determining the allowable load bearing capacity of the pile.
