Investigation On Quantitative Reduction Of Oily Sludge Through Dewatering Method

Because of large amount, high water content and environmental stresses of oily sludge, quantitative reduction and dewatering of oily sludge requires particular attention. Inveatgating on the dewatering performance of three kinds of oily sludge, SLT3, SLNH, and SLT2, from Shengli Oil Production Plant through pressure filtration method, the purpose of this work is developing a laboratory scale dewatering plant for oily sludge, so as to provid a theory basis for oily sludge disposal on large scale.The influences of adding different filter aids and flocculants on dewatering performance of oily sludge by pressure filtration method were experimentally investigated. Cheap, easily gained filter aids, such as HTK and GLF, and flocculants, such as cationic polyacrylamide, anionic polyacrylamide and polyaluminium chloride, were used in aidding filtration. The effect of these agents were investigated and finally excellent auxiliary agents were selected. The results show that the low-oil-content, large-sand-size SLT3 oil sludge can be directly filtrated under low filtration pressure and the filter cake has low water content. It was also found that the solid concentration of the suspension has some effect on filtering, so dilution of the oily sludge suspension is perhaps of benefit to filter.At low filtration pressure, SLNH oily sludge, which has high oil content and small sand size can be direct filtered. Both water content of the filter cake and filtering velocity are very low. Filter aids such as HTK, GLF can speed up the filtering velocity and bring down the specific resistance, making the filter cake much regular and massy. But this effect is limited. Small dosage of flocculants can cut down the filtration time greatly, and the filtrate is clear. But it has some defects such as the filter cake being not massy enough. For making the discharge of filter cake easier, both flocculant and filter aid can be used to aid filter. It is found that cooperation of 1# polyacrylamide and GLF is beneficial to filter.The influences of filter aid and flocculant on dewatering performance of SLT2 oily sludge are investigated and the optimal dosage was determined. The results showed that 1# polyacrylamide is better than others and the optimal proportion is 0.022wt%. Meanwhile, if 1# polyacrylamide was combined with not less than 0.4wt% GLF filter aid, the filtering effect is better. The filter media's repetitive test proved that the monofilament filter cloth is the best.Form trials of the laboratory scale frame filter and the skid-mounted pilot plant on the spot, it found that adding filter aid and flocculant are of advantage for filtering and the filter cake has low water ratio, which can meets the transportation requirement.