| Aerobic composting is one of the main ways in rural living garbage disposal.But composting leachate,which is seriously polluted,complex in composition and high concentration,is produced in the process of aerobic composting.In general,the content of ammonia nitrogen,organic pollutants,heavy mental and inorganic macromolecules,is high,and the water quality density fluctuates siginificantly.Based on the specificity and strong volatility in water quality,it's urgent to collect effectively and dispose properly the leachate in the vast rural areas.In this experiment,the leachate from aerobic composting of rural living garbage was taken as the research object.As a efficient reactor in the biochemical experiment,the double-aeration and double sludge-layer filtering reactor,which is designed by our team,was a invention patent?patent number: ZL20101 0573254.4?.Using a continuous aeration and continuous influent operational mode,the experiment studied the removal efficiency of nitrogen and carbon under the condition of low and high concentration and different volumetric loads.And the experiment lasted for 166 days.Combining the double-aeration and double sludge-layer filtering reactor process with coagulation process in the experiment of coagulation and biochemical,the paper analyzed contrastively the process of coagulation + biochemical and the process of biochemical+ coagulation from the aspects of the removal efficiency of COD and NH3-N,the sludge production and the economic cost.And this part of the experiment lasted for 18 days.The conclusions of the two experiments are as follows:?1?In the stage of low concentration feed water,the experiments were carried out under the three conditions of 0.6kgCOD /?m3 · d?,1.2kgCOD /?m3 · d?and1.8kgCOD /?m3 · d?.The results showed that the removal efficiency of COD was stablized at 89%91% and the COD concentration of effluent was maintained at 200280 mg/L,and the removal efficiency was similar under the three volumetric loading conditions.The removal efficiency of NH3-N was best under the condition of1.8kgCOD /?m3·d?,stabilized at 98% 99%.And the effluent concentration was maintained at 38mg/L.The optimum operating conditions of 1.8kgCOD /?m3·d?were as follows,HRT was 47 h,the sludge reflux ratio was 100%,the DO?dissolved oxygen?of the first and secod aeration zone was stablized at 24mg /L and0.5-1.0mg / L.?2?In the stage of high concentration water inflow,the test was carried out under the conditions of 0.6 kgCOD /?m3 · d?,1.2kgCOD /?m3 · d?and 1.8kgCOD /?m3 ·d?.With the gradual increase of volume load,the effluent concentration of COD and NH3-N increased step by step,and the removal rate descended step by step at the same time.The effluent concentration requirements of leachate was based on the advanced film processing in the practical engineering.And the effluent concentration can meet the relevant requirement when the volume load of COD is less than1.3kgCOD /?m3 · d?in the high concentration stage.The optimal operation load was1.2kgCOD /?m3 · d?in this stage.The COD concentration of effluent was stabilized at 800 900mg/L,the removal rate was stabilized at 97%98%,and the NH3-N concentration of effluent was maintained at 10 19 mg / L,the removal rate was stabilized at about 99%.The removal rate of total nitrogen was stabilized at 97% 98%,the effluent concentration was maintained at 37 58mg/L.?3?In the stage of Coagulation and biochemical process,the combined process was used to treat high concentration compost leachate,and the results were compared and analyzed from the three aspects: operation treatment effect,sludge production amount and operation cost.The results showed that the process of biodegradation +coagulation and sedimentation is better than the process of the coagulation sedimentation + biodegradation.And the optimum pH of coagulant FeCl3 is about 8.0,the best dosage is 700 mg /L.The removal rate of COD and NH3-N in the combined process was 98% 99% and 99%,the effluent concentration of COD and NH3-N was maintained at 401 474 mg / L and 11 13.6mg/L.This paper provides a reliable and efficient pre-treatment method for post-treatment NF / RO double-membrane depth treatment,which has certain reference value and application prospect for the practical engineering application ofcompost leachate treatment. |
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