Global NEST Journal

One of the space-saving and alternative options for wastewater treatment is the use of Membrane Bio-Reactor. This paper delineates the sequential approach to explore integrated cost functions for estimation of the forecast level cost for biological treatment of wastewater by use of Membrane Bio-Reactor. The cost functions for capacity wise small range, medium range and large range groups of wastewater treatment plants with Membrane Bio-Reactor have been developed based on process design and cost estimation. It has been established through regression analysis that they are best expressed by polynomial equations. Validation of cost functions has been executed by assessment of mean absolute percentage errors. The respective determination coefficients in respect of cost functions for capacity wise small range, medium range and large range are 1, 0.9995 and 0.9996. The respective mean absolute percentage errors with reference to the cost functions for capacity wise three different ranges are 0.18 %, 0.82 % and 0.63 %. In each case the value of mean absolute percentage error is well below 10 %. This study has established that accurate forecast level cost may be arrived by integrated cost functions developed for capacity wise three different groups of wastewater treatment plants with Membrane Bio-Reactor.

Researchers have been focusing on protecting water quality and preventing environmental contamination caused by industrial discharge of heavy metals. Various methods have been explored for extracting these metals from wastewater, but they often prove to be costly and rely on non-renewable resources. Adsorption, however, offers a promising solution due to its stability, affordability, and ease of implementation. In this research, continuous biosorption tests were conducted using a glass column filled with Sargassum Wightii (SW) seaweed, with Pb(II) ions used as a model solute. Varying bed heights (15-25cm) and flow rates (0.3-0.6 L/hr) in the column tests aimed to maximize biosorption efficiency. The optimal conditions for metal uptake and removal were a bed height of 25cm and a flow rate of 0.3L/hr, resulting in Sargassum Wightii adsorbing 41.17mg/g of metals with a removal efficiency of 69.07%. The Modified dose-response model effectively characterized Pb(II) biosorption at different bed heights and flow rates. Column regeneration studies demonstrated breakthrough and sorption within 2 hours, complete depletion at 24 hours, and an elution efficiency of 99.2% using 0.1M NaOH, allowing for up to three cycles of biosorbent reuse.

Anaerobic digestion of piggery wastewater mediated with biochar was investigated by COD removal rate, methane yield, process stability and microbial community analysis. The results showed that biochar could effectively improve the COD removal rate and methane yield. Compared with blank group, COD removal rate was increased by 2.3%-9.4% for 300BC and by 37.5%-44.0% for 500BC. The maximum methane yield was obtained in 1g 300BC and 500BC, which was increased by 43.20% and 89.52% respectively. Meanwhile, the final H2S concentration was also obviously decreased by BC. Microbial community analysis showed that the addition of BC could increase the abundance of methanogens compared with the blank group. 500BC had a higher positive effect on anaerobic digestion of methanogenic bacteria than 300BC.Meanwhile, the relative abundances of hydrotrophic methanogens in 500BC groups were significantly higher than that of acetoclastic methanogens in 300BC.

Dual-chamber microbial fuel cell (MFC) was constructed to treat heavy metal wastewater (Pb2+ solution). The results showed the maximum voltage, the maximum electric power density and pb2+ removal were 9.6 mV, 371.0 mV/m2 and 52.3% respectively. The effects of different cathode chamber environments on the production potential (V, volts) and Pb2+ removal rate of strained CD-1 were investigated. The results show that when the cathode chamber is soil, the maximum voltage is 8.88mV, and when the cathode chamber is solution, the maximum voltage is 12.11mV. The removal efficiency of heavy metals polluted from near to far from the electrode plate in the soil is 68.9%, 62.1%, 57.5%, and the removal efficiency of heavy metals in the solution is 67.46%. It can be concluded that when the soil is the cathode chamber. The removal rate of local heavy metals was the highest. When the solution was used as a cathode chamber, the average removal rate of heavy metals was the highest. The bacteria, named strain CD-1, as the electricity production bacteria (EPB) used in the dual chamber microbial fuel cell (MFC), was isolated from activate sludge and identified on its morphology, physichemical properties and phylogenetic positions. The results indicated that strain CD-1 was Gram-negative, rod. Oxidase and catalase reactions were positive. Strain CD-1 could use gluconate, lactose, D-fructose, L-Arabinose, D-arabinose, acetate, propionate, butyrate, lactate, sucrose and glucose, not use melibiose, galactose, N-acetylglucosamine, ethanol and glycerol.16S rRNA gene sequences analysis showed that strain CD-1 was most related to Ochrobactrum sp. (AJ245941）with the homology similarities of 98%. Based on the above results, strain CD-1 was belonged to the genus of Ochrobactrum and seemed to represent a novel species.