Influence of Biomass Ash Residues of Power Plant on Treatment Effectiveness for Micro-Polluted Raw Water
The treatment and disposal of biomass ash residues(BAR)were investigated in this study.The BAR with different particle sizes(i.e.,L1 with a range of 0.25～0.50 mm,L2 of 0.50～1.00 mm,L3 of 1.00～2.00 mm,L4 of 2.00～4.00 mm and L5 of 4.00～8.00 mm)were obtained by magnetic separation,screening,and cleaning via a multi-layer mesh synchronous screening machine.The effect of particle size of BAR on the purification effectiveness of micro-polluted water was verified by rapid small-scale column tests(RSSCT).The characterizations of BAR were detected by the scanning electron microscopy(SEM),X-ray diffraction(XRD),and fourier transform infrared spectroscopy(FTIR),respectively.The adsorption effectiveness was evaluated via outflow turbidity,chemical oxygen demand(CODCr),and the content of total phosphorus(TP)and ammonia nitrogen within 15 days.The results showed that the L2 and L3 possessed superiority purification effectiveness,of which the average removal rates of outflow turbidity,CODCr,and TP reached over 88%,40%and 35%,respectively due to the higher adsorption capability of BAR and microbial degradation.The rejection effectiveness of ammonia nitrogen of L4 and L5 with large particle size reached 95%due to the improved biological activity of nitrifying bacteria as their low filling density and sufficient oxygen content in the later stage of operation(11～15 days).However,the bulk density and filling density of L1 with the smallest particle size were relatively high.Therefore,the water flow faults,oxygen deficiency,and insufficient microbial activity occurred,hindering the removal of various pollutants in the raw water.In addition,the M-L2,modified by citric acid and chitosan,increased the removal rates of CODCr and TP in raw water from 42.05%and 40.97%to 80.28%and 60.36%,respectively compared to L2.The improved effectiveness of M-L2 was comparable with that of common packings(i.e.,zeolite and ceramsite)on the market and the cost was lower.The research results provide certain support for the high-value application of BAR with different particle size and the development of modified BAR in the pre-treatment technology of micro-polluted water.
biomass ash residues(BAR)particle sizepackingmodificationmicro-polluted raw water
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