Pilot Study On Filter Cloth Filter Technology

An advanced municipal wastewater treatment process with cloth media filtertechnology has been used in engineering in foreign countries, but up to now there aren’tsuccessful large scale application samples in China. Therefore, pilot study on cloth mediafilter technology in Shenzhen sewage treatment plant is significant, and it can be veryhelpful for the design and operation of the technology in our country. Through long-termoperation and revelant research, the main conclusions of this paper are as follows:(1) Firstly, through a large number of beaker tests, we selected five drugs includingferric chloride, polyaluminium chloride, polyaluminum ferric chloride, ferrous sulfate andpolymeric ferric sulfate, and choose ferric chloride, PAFC and PAC as the coagulant of thepilot study. Secondly, through the analysis of different agents, adding coagulant andcoagulant mixing mode for the water pollutant removal effect in project part I of Luo-Fangsewage treatment plant, the test result shows that after adding coagulant, the effect isapparent for ferric chloride coagulant on the turbidity removal, not apparent for PAC andphosphorus promotes. PAFC has both disadvantages of iron salt and aluminum salt. As canbe seen from the backwash frequency, filter cloth filter economy had a greater negativeinfluence after adding coagulant. There is not apparent promotion for coagulant in clothmedia filter technology.(2) Pilot study using cloth media filter technology in project part I of Luo-Fangsewage treatment plant reveals that ferric chloride and PAC had very little effect on theremoval of turbidity and TP under different running water conditions. The removal rate ofTP increased with the increase of amount of wastewater when adding PAC or ferricchloride, but the two drugs had litter effect on nitrogen removal, and there have an adverseeffect on chroma and turbidity of effluent when ferric chloride dosage is too high. Thebackwash frequency of the system increased with the increase of dosage, the backwashfrequency of PAC (60times per day) is higher than that of ferric chloride (37times per day).The addition of ferric chloride on cloth media filter had effect on the chroma of effluent,the maximum of chrominance reached17times when the adding dosage was above9mg/L.SS concentration of backwash water is at high level of200mg/L, SS concentration ofwastewater from discharging mud is at low level of20mg/L.(3) Pilot study using cloth media filter technology in project part ш of Bin-He sewage treatment plant reveals that:①the turbidity in the effluent is over3UNT whenferric chloride dosage exceeds15mg/L, COD removal rate of the system is below10%andTN removal rate20%;②the turbidity in the effluent is below3UNT when PAC dosage isless than8mg/L, elimination capacity of TP by PAC is superior to that by ferric chloride.COD removal rate of the system is at the range of8~55%and TN removal rate30%;③backwash frequency of the system increased with the increase of dosage, backwashfrequency by PAC is higher than that by ferric chloride;④SS concentration in the effluentincreased with the increase of dosage, PAC dosage should not be more than5mg/L andferric chloride dosage3mg/L while SS concentration in the effluent10mg/L can bereached.