Study Of Pollutants Produced In Municipal Refuse Container In Transfer Process

With the acceleration of urbanization, the production of municipal refuse increase quickly. As a combining site between waste generation area and end disposal system, the refuse transfer stations are becoming more and more important. In order to increase running efficiency and reduce impact on surrounding environment, Shanghai take the lead in using container as refuse carrier. However, there will be waste water and odor generated from the containers, and there is no studies yet.The regularly monitoring and assay of the odor and leachate generated in the container in a transfer stations in Shanghai were studied within a year. The seasonal change of odors and leachate in the container, the relationship of pollutants and environmental conditions (temperature, humidity and so on) and working operation (quantity of refuse, density of compaction and so on) were analyzed. Then the optimization operation conditions and the strategies of pollution prevention were suggested. The conclusions are as followings:(1) In summer, the temperature inside the container is generally higher than that outside the container, which is on the contrary in winter. The concentration of H2S was in range of0.3-10.3mg/m3, the concentration of CH4was in range of0.02-2.97%and the concentration of NH3was in range of0.7～4.5mg/m3, and they all reached the highest in summer. In contrast, the concentration of VOC reached the highest in winter. The pH of the leachate was in range of5.4～6.3, COD was41633～84060mg/L, BOD was18116～34130mg/L, and these three pollution were all higher in winter than in summer. The ammonia concentration was in range of537.33～1222.48mg/L. While the TP fluctuated acutely in range of17.98～296mg/L. The change of sand removal was consistent with SS, which didn’t change with the seasons.(2) Extreme temperature had effect on the odor produce in the container obviously. The concentration of H2S, CH4and NH3in the extreme high temperature was much higher than that of annual mean. But VOC in the extreme low temperature was higher. It is alert to pay attention to CH4generated in summer. COD and BOD in extreme low temperature were higher than extreme high temperature and annual mean, and pH was close to neutral. There was nearly no obvious difference between the ammonia concentration in two extremes. TP drop to bottom in the extreme high temperature. Sand removel and SS fluctuated a lot and didn’t show obvious difference in two extremes.(3) Rainning affects the odor index inside the container obviously. H2S, CH4and NH3in dry month were much lower than those in humid month, but the VOC was on the contrary. COD, BOD and ammonia diluted by rain were much lower than those in dry month. TP and sand removel in humid month were higher than that in dry month, while SS was on the contrary.(4) In the density of compaction of0.49t/m3and0.61t/m3, although the concentration of odor generated in high density was a bit higher than that in the low one, the pollution index in two containers didn’t show obvious differernce.(5) All the odor index reached peak in1-2days, then gradually decreased, and remained stalbe in4-5days. The downside was notable in summer, and rain had obvious impact on the decrease of odor index. The index changed with the temperature within a day. The organics rised while the ammonia dropped in the leachate. The pH of leachate increased slightly in August. The ammonia concentration in October and December showed obvious rising trend. Sand removel and SS fluctuate the most significantly.(6) During the whole experimental period, the variation trend of odor index in each point is basically the same. In each season, the odor index in the tail part was the highest, and the middle part was a little higher than the top part. They all decreased with the time and changed with the temperature.(7) The leachate production rate of refuse in the container within the experimental period is about1-2%, and the the height of leachate level is about40cm-60cm.(8) PCA and correlation analysis results showed that there were certain relationships among temperature inside container, temperature outside container, CH4 and H2S. Good correlation can be found between pH and BOD, ammonia, VOC and COD as well. However, the relationship of TP, SS, sand removel and quantity of refuse was not obvious. It indicates that high temperature is the main reason of odor generation and NH3and VOC can be reduced by reducing organics in the leachate.