Study On The Treatment And Reuse Of Municipal Wasterwater By Means Of BAF-CMF Technology

Serious devoid of water resource and deteriorated water environment have been popular concerned problem at present. The reuse of the municipal wastewater is an important measure to solve the scanty water resource. The rapid rising ratio of operating water costs to running expenses requires municipal wastewater reclamation for supplying water in Harbin generate electricity corporation. The article proposed adopting the combined technology of two-step biological aerated filter (BAF) and continuous micro filtration (CMF) for municipal wastewater reclamation. The test based on the natural municipal wastewater and pilot scale was conducted. The objective of this test was to determine the optimal operation status and parameters and offer references for project design by detecting the water quality indexes such as COD,NH4+-N,SS and optimizing the main operation parameters such as upflow velocity, the ratio of air to water, shock loading.The main results are summarized as follows:1.It was feasible for municipal wastewater reclamation by BAF-CMF technology and the effluent completely complied with the recycle requirements. The effluent of BAF-CMF technology excelled living water quality standard (CJ25.1-89), while effluent of two-step BAF technology preceded first grade discharge standard of pollutants for municipal wastewater treatment plant (GB18918-2002) and reuse water for sight water quality standard designed by construction ministry in 2000. The results indicate that the BAF-CMF technology has a good prospect.2.The BAF-CMF technology was applied in municipal wastewater recycle in Harbin generate electricity plant with unit investment:1482.52$/t and unit operation cost:0.681 $/d. The project could produce water 219,0000 t and save 4202.6 thousand $.The study suggests BAF-CMF is an economic technology.3.Two-step BAF technology has a good shock load resistance. The effluent of COD,NH4+-N,SS were less than 30mg/L, 5mg/L, 20mg/L respectively when the corresponding load reached 16.07, 2.65, 8.18 kg/(m3·d) separately.4.The results of back-flush test on two-step BAF illustrated that back-flush by influent had little effect on operation period. The back-flush frequency were 1~2d and 2~3d respectively for BAF(C) and BAF (N). The effluent of COD and SS were below 25mg/L and 15mg/L separately after 1.5h resuming and effluent kept on steadily after 2.5h.5.Two-step BAF had high removal efficiency with COD,NH4+-N,SS achieved 94.7%, 90.1%, 85.7% respectively under the economic operation parameters which the ratio of air to water was 2:1 for two steps and upflow velocity was 2.5m/h. The technology achieved 73% phosphorus removal rate while effluent TP still exceeded 1mg/L that was stipulated by discharge standard and chemical dephosphorization was required.