Hassan Ahmed Hossam, Ramadan Mohamed Hassan
Environmental Heath Dept., High Institute of Public Health, Alexandria University.
J Egypt Public Health Assoc. 2005;80(1-2):27-49.
The total amount of solid waste generated in Alexandria is 2820 tons/d which increases to 3425 tons/day during summer. In the past, 77% of the collected solid wastes was open dumped. The open dumping sites did not have the minimum requirements for pollution control. Following the exacerbation of the problem, the Alexandria Governorate contracted a company to carry out the solid waste management. The contracted company transferred 75% of the daily generated solid wastes to a new constructed sanitary lanfill. The site receives a daily average of 1910 tons. The landfilling is performed by trench method in the form of cells. The produced leachate is discharged into two lined aerated lagoons. The biogas formed from biodegradation of landfilled solid wastes is burned and the produced heat is used for drying the lagoons leachate. The remaining residues are relandfilled. The study aims at assessment of the solid waste sanitary landfill leachate characterization and its impacts on the groundwater. The analysis of the collected data confirms that leachates from the landfill are severely contaminated with organics, salts, and heavy metals. The fluctuations in concentration levels of the different parameters were attributed to aging and thickness of waste layers, stage of decomposition, and re-landfilling of the concentrated residues from the drying lagoons. The concentrations of NH4-N (600 mg/l) indicated that the process of stabilization was still in the initial stages and attributed to the compaction process. The high BOD5 results (28,833 mg/l) indicated that the process of stabilization was in the initial stages which were very slow. The high COD results (45,240 mg/l) can be attributed to the compaction of the wastes which also retards the degradation of the solid wastes. The BOD and COD values indicated clearly severe contamination. The BOD5/COD ratio measured in the current study (0.64) indicated that the leachate of the present study was biodegradable and unstabilized, and required time and favourable conditions for anaerobic biodegradation. Heavy metals were lower compared with what have been observed in other countries. Re-landfilling of the residue after drying the leachate in lagoons and the short time of biodegradation in the landfill site were factors which effected the high strength of most of the parameters concentrations of the leachate. Assessment of groundwater contamination through piezometer wells around the active cells indicated that there was no contamination from the leachate to the groundwater surrounding the site. The study recommended emphasizing the importance of adjusting the biodegradation factors, the monitoring program, the prohibition of disposing heavy metals, determination of the leachate generation rate, and treatment of leachate.
亚历山大港产生的固体废物总量为2820吨/天，夏季增加到3425吨/天。过去，收集到的77%的固体废物被露天倾倒。露天倾倒场没有污染控制的最低要求。随着问题的加剧，亚历山大港省政府与一家公司签约进行固体废物管理。该签约公司将每日产生的75%的固体废物转移到新建的卫生填埋场。该场地平均每天接收1910吨。填埋采用单元式沟槽法进行。产生的渗滤液排放到两个有衬里的曝气塘中。填埋固体废物生物降解产生的沼气被燃烧，产生的热量用于干燥塘中的渗滤液。剩余的残渣被重新填埋。该研究旨在评估固体废物卫生填埋场渗滤液的特性及其对地下水的影响。对收集数据的分析证实，填埋场的渗滤液受到有机物、盐分和重金属的严重污染。不同参数浓度水平的波动归因于废物层的老化和厚度、分解阶段以及干燥塘浓缩残渣的重新填埋。NH4-N的浓度（600毫克/升）表明稳定化过程仍处于初始阶段，这归因于压实过程。高BOD5结果（28833毫克/升）表明稳定化过程处于非常缓慢的初始阶段。高COD结果（45240毫克/升）可归因于废物的压实，这也阻碍了固体废物的降解。BOD和COD值清楚地表明污染严重。本研究中测得的BOD5/COD比值（0.64）表明本研究的渗滤液可生物降解但未稳定化，需要时间和有利条件进行厌氧生物降解。与其他国家观察到的情况相比，重金属含量较低。在曝气塘中干燥渗滤液后对残渣进行重新填埋以及填埋场中生物降解时间较短，是影响渗滤液大多数参数浓度高强度的因素。通过活动单元周围测压井对地下水污染的评估表明，渗滤液对场地周围的地下水没有污染。该研究建议强调调整生物降解因素、监测计划、禁止处置重金属、确定渗滤液产生速率以及处理渗滤液的重要性。
