Research On Advanced Treatment Of Wastewater By Walnut Shell Filtration

This article makes a testing facility to filter function of walnut shell-filter, according to the the new material—walnut shell-filter—that used in the advanced treatment process of domestic wastewater treatment.The main tests include (1) filtering effect and mechanism of. filter.Analysis media size, filtration rate, coagulant dosage on the removal rate of turbidity, CODcr, TP, TN and others,in order to determine the optimal filter and the best conditions,study walnut shell filtration column of the turbidity, CODcr, TP and TN removal effect,analyze the removal mechanism; (2)the effect of anti-washout.Anti-washout effect is determined to find out the best walnut shell filter flushing intensity, wash time, rinse cycle, for the reference value of the actual production process.The best diameter of walnut shell is 0.8～1.2mm;the best L/d10=1000,the best filter thickness is 800mm;the best filtration rate is 5m/h; Coagulant is PAC, the optimal dosage is 5mg/L, the filtration time was 40min.Filtration tests showed that filtered by walnut shell media, the water quality of CODcr, TP and other indicators have reached the level A standard, CODcr have 17% removal rate, TP have 30% removal rate.Compared to the conventional treatment effect of quartz sand, walnut shell media for the depth of wastewater treatment plant secondary effluent treatment works well,the use of walnut shell filter in wastewater treatment filter performance is feasibility.Anti-washout experiment showed that optimum parameters of walnut shell filter anti-washout (1)the strength of individual gas flushing is 10L/m2.s, washing time is 15s; (2)the strength of rinse water mixed gas:the strength of gas flushing is 10L/m2. s, the strength of water flushing is 8L/m2.s, washing time is 6min; (3) the strength of individual water flushing:the strength of individual water flushing is 8L/m2.s, washing time is 6min; (4) the total washing time is 12-13min.The effect of anti-washout is the results of interaction between particle collision and shear from the surface of the filter.Comparison with the conventional quartz sand filter anti-washout, the fluffy of walnut shell is larger,the interception and adsorption of impurities in the filter surface is easily separated.The anti-washout effect isbetter.