灰渣填埋场渗滤液处理技术研究

垃圾渗滤液,又称渗沥水或浸出液,是指垃圾在堆放和填埋过程中由于发酵和雨水的淋浴,冲刷,以及地表水和地下水的浸泡而滤出来的污水。垃圾填埋场渗滤液是一种高浓度有机废水,其化学特性与填埋场废物成分、填埋方式、填埋龄以及填埋场环境条件等密切相关,一般评价渗滤液的指标包括:COD Cr、BOD5、SS、总氮、氨氮、重金属等,主要污染物为溶解性有机物、氨氮,无机盐类物质含量较高,一般都极难处理而且会对周围环境造成严重的影响,特别是渗入到地下影响地下水,对周围的居民和植物的生存有很大的影响,渗出的渗滤液味道十分难闻也会产生沼气,影响大气环境。因此渗滤液的处理是城市垃圾填埋场正常运行的必不可少的环节之一。本次课题通过实验对渗滤液进行不同技术路线处理,探索渗滤液的有效方法。     

Polyfluoroalkyl compounds in landfill leachates

Polyfluoroalkyl compounds (PFCs) are widely used in industry and consumer products. These products could end up finally in landfills where their leachates are a potential source for PFCs into the aqueous environment. In this study, samples of untreated and treated leachate from 22 landfill sites in Germany were analysed for 43 PFCs. ΣPFC concentrations ranged from 31 to 12,819 ng/L in untreated leachate and 4-8060 ng/L in treated leachate. The dominating compounds in untreated leachate were perfluorobutanoic acid (PFBA) (mean contribution 27%) and perfluorobutane sulfonate (PFBS) (24%). The discharge of PFCs into the aqueous environment depended on the cleaning treatment systems. Membrane treatments (reverse osmosis and nanofiltrations) and activated carbon released lower concentrations of PFCs into the environment than cleaning systems using wet air oxidation or only biological treatment. The mass flows of ∑PFCs into the aqueous environment ranged between 0.08 and 956 mg/day.     

Performance of bioreactor landfill with waste mined from a dumpsite

Emissions from landfills via leachate and gas are influenced by state and stability of the organic matter in the solid waste and the environmental conditions within the landfill. This paper describes a modified, ecologically sound waste treatment technique, where municipal solid waste is anaerobically treated in a lysimeter-scale landfill bioreactor with leachate recirculation to enhance organic degradation. The results demonstrate a substantial decrease in organic matter (BOD 99%, COD 88% and TOC 81%) and a clear decrease in nutrient concentrations especially ammonia (85%) over a period of 1 year with leachate recirculation.     

渗滤液循环回灌出水在混凝处理中的去除特性

经循环回灌后的渗滤液出水含有大量的腐殖质,其生物降解性差、氨氮含量高,具有类似长填龄填埋层渗滤液的水质特征。用混凝法处理渗滤液循环回灌出水,通过混凝pH、混凝剂种类及其投加量实验,确定了最佳混凝条件;并通过分析混凝处理前后渗滤液循环回灌出水的分子量变化和从出水中分离出的腐殖酸(HA)、富里酸(FA)和Hydrophilic(HyI)三种组分的变化,讨论了混凝法对渗滤液循环回灌出水去除效率不高的原因。研究表明,聚合硫酸铁(PFS)在pH=5、投药量为0.22g/L(以Fe2O3计)的条件下的混凝效果最佳,其对渗滤液循环回灌出水的COD去除率达58.1%。混凝剂对渗滤液循环回灌出水中的HA、FA和HyI组分的去除效果依次为:HA>FA>HyI。     

回灌对垃圾填埋初期渗滤液化学需氧量的影响

通过模拟柱实验 ,研究了回灌对垃圾填埋场初期渗滤液 CODCr的影响。研究结果表明 ,模拟降雨雨水的渗入且无渗滤液回灌的参照柱 ,其渗滤液出水 CODCr最高 ,一般在 70 0 0 0 mg/L 左右 ;模拟渗滤液原液回灌 ,从第 4周起因脂肪酸的积累导致渗滤液的 p H低于 6,从而抑制了微生物的生化反应 ;模拟好氧生物处理后渗滤液的回灌 ,能加速垃圾层 CODCr的溶出和甲烷化阶段的建立 ,且此时渗滤液的 CODCr变化规律符合指数方程 ;当垃圾层建立甲烷化阶段后 ,回灌 CODCr在 2 0 0 0 0 m g/L 左右的渗滤液 ,仍可促使垃圾中有机物迅速转化为气态物     

固体废弃物填埋场中土工膜衬垫系统的发展与应用

固体废弃物填埋场中产生的渗滤液污染土壤和地下水 ,在填埋场正确设置防渗的衬垫系统是非常重要的。本文对国外土工膜衬垫系统在填埋场中的发展应用进行介绍和评价 ,分析了土工膜的选用原则 ,有助于我国合理和有效的进行土工膜衬垫的设置     

Leachate formation and characteristics from gasification and grate incineration bottom ash under landfill conditions

Characteristics and formation of leachates from waste gasification and grate firing bottom ash were studied using continuous field measurements from 112 m³ lysimeters embedded into landfill body for three years. In addition, the total element concentrations of the fresh ash were analysed and laboratory batch tests were performed to study leachate composition. The three-year continuous flow measurement showed that about one fifth of the leachates were formed, when the flow rate was >200 l/d, covering <3.5% of the study time. After three years, the liquid/solid-ratio for the quenched grate ash was 1 (l/kg (d.m.)) and for the initially dry gasification ash 0.4 (l/kg (d.m.)). The low initial water and residual carbon content of the gasification ash kept the leachate pH at a high level (>13) major part of the study. In the grate ash leachate pH was lower (<8) due to the presence of organic carbon and biodegradation indicated by biological oxygen demand and redox potential measurements. In the gasification ash the high pH probably delayed leaching of major elements such as Ca, therefore, raising the need for a longer after-care period. The high pH also explains the higher leaching of As from the gasification ash compared to the grate ash both in the batch test and under landfill conditions.     

Assessing the feasibility of wastewater recycling and treatment efficiency of wastewater treatment units

Wastewater reuse can significantly reduce environmental pollution and save the water sources. The study selected Cheng-Ching Lake water treatment plant in southern Taiwan to discuss the feasibility of wastewater recycling and treatment efficiency of wastewater treatment units. The treatment units of this plant include wastewater basin, sedimentation basin, sludge thickener and sludge dewatering facility. In this study, the treatment efficiency of SS and turbidity were 48.35–99.68% and 24.15–99.36%, respectively, showing the significant removal efficiency of the wastewater process. However, the removal efficiencies of NH₃–N, total organic carbon (TOC) and chemical oxygen demand (COD) are limited by wastewater treatment processes. Because NH₃–N, TOC and COD of the mixing supernatant and raw water are regulated raw water quality standards, supernatant reuse is feasible and workable during wastewater processes at this plant. Overall, analytical results indicated that supernatant reuse is feasible.     

Governmental Oversight of Discharges from Concentrated Animal Feeding Operations

As point sources of pollution in the United States, concentrated animal feeding operations (CAFOs) are subject to the National Pollution Discharge Elimination System permitting system requirements. Changes to federal regulations in 2003 and a 2005 court decision have increased the governmental oversight of CAFOs. Manure application to fields from “large CAFOs” that results in unpermitted discharges can be regulated under the Clean Water Act. The U.S. Environmental Protection Agency’s interpretation of agricultural stormwater discharges was approved so that unpermitted discharges may arise if an owner or operator of a CAFO fails to apply manure correctly. Owners and operators do not, however, have a duty to secure governmental permits in the absence of a discharge. Turning to the federal provisions regarding nutrient management plans, a court found that they were deficient. Moreover, the federal government needs to reconsider requirements that would reduce pathogens from entering surface waters. Although these developments should assist in reducing the impairment of U.S. waters, concern still exists. Greater oversight of nutrient management plans and enhanced enforcement efforts offer opportunities to provide greater assurance that CAFO owners and operators will not allow a discharge of pollutants to enter surface waters.