生活垃圾填埋场陈垃圾基本特性及再利用

填埋场已填埋陈垃圾具有丰富的资源,我国填埋量已达几千万吨.通过对上海老港生活垃圾填埋场6年填埋龄和10年填埋龄陈垃圾基本特性的测试研究,揭示出填埋6年以上的陈垃圾已具有相当稳定的性状,原始垃圾特征已完全消失,开挖后没有异味,在组成上除部分大颗粒无机物和大块难降解有机物外,其余部分已腐化为类土壤物质,可以开采再利用.陈垃圾中类土壤部分在物理化学性质、水力学和微生物学性质上均表现出在自然条件下难以形成的、极为优良的基质特征,可用作污染物生物处理基质或作物培育基质.     

城市生活垃圾预处理和资源化研究

分析了国内外近期生活垃圾资源化技术的处理模式和存在的缺点,指出了我国城市生活垃圾资源化的有效途径是加强对垃圾的预处理,提出了基于垃圾预处理的城市生活垃圾资源化综合处理系统,介绍了废塑料制作建筑板材的工艺和技术指标.     

进场垃圾的筛分特性试验研究及优化处理

通过深入现场的调查、实验研究,对深圳老虎坑环境园的进场垃圾进行物理成分及理化特性分析.测定了进场垃圾的容重、物理组成、含水率、发热值等基础数据,为废弃物的减量化、无害化与资源化提供了依据.特别是通过垃圾的筛分实验,提出了80 mm、60 mm的筛上物进垃圾焚烧厂的优化处理方案.     

上海市生活垃圾全程分类模式的研究和实践

提出了生活垃圾全程分类模式。通过试点,着重论述与该模式相对应的工作内容和方法,对城市生活垃圾的减量化、资源化、无害化推进具有指导意义。     

Comparison of semi-aerobic and anaerobic degradation of refuse with recirculation after leachate treatment by aged refuse bioreactor

Two fresh refuse bioreactors (F1 and F2) were operated under semi-aerobic and anaerobic conditions, respectively. The leachate from the bioreactors F1 and F2 was introduced into the aged refuse bioreactors (A1 and A2), and the effluent from A1 and A2 was subsequently recirculated into F1 and F2, respectively. The effect of the semi-aerobic recirculation process on refuse degradation was investigated, comparing it with that of the anaerobic recirculation process. Results indicate that the semi-aerobic recirculation process can increase the accumulated net production of leachate and promote evaporation. The accumulated net production of refuse in F1 is 320 mL/kg and that of F2 is 248 mL/kg, with leachate reduction amounting to 315 and 244 mL/kg refuse, respectively. The leachate quantity reduction of semi-aerobic and anaerobic leachate recirculation process accounted for 98.4% and 98.3% of the accumulated net production of leachate, respectively. The semi-aerobic leachate recirculation process can improve the biodegradation of organic matter from fresh refuse and the reduction rate of the pollutant concentration in leachate. This should shorten considerably the time required to meet the discharge standard and the time of stabilization of the refuse as observed in the anaerobic recirculation process. It was predicted that the COD concentration of leachate from the anaerobic recirculation process would reach 1000 mg/L in the anaerobic recirculation process after 2.2 years, as for semi-aerobic leachate recirculation process it is about 100 days. Compared with anaerobic recirculation process, the semi-aerobic recirculation process is more effective on NH₃-N transformation and TN removal. The NH₃-N and TN concentration of F1 is far below those of F2 at the end of our experiment. Refuse settlement in the semi-aerobic recirculation process was faster than that in the anaerobic recirculation process. At the end of the experiment, refuse settlement ratios in the semi-aerobic and anaerobic bioreactors were 33.5% and 18%, respectively.     

Recycling of aged refuse from a closed landfill.

In this study, refuse excavated from a typical refuse landfill in Shanghai after 8-10 years of placement was characterized in terms of particle size, total nitrogen, total phosphorus, and biodegradable matter. The refuse contained a large and diverse population of micro-organisms with a high capacity for decomposing refractory organic matter present in some wastewaters, including leachate. It was found that the aged refuse was quite stable after about a decade of decomposition in the warm, humid climate of southern China. The fine fractions resembled and had the properties of black soil, a medium that is suitable for green construction, organic fertilizer, or as bioreactor media for biological treatment of organic wastewaters. Excavation of the aged refuse would make about 50% of the space available for fresh refuse. The plastics, glass, textiles, and cans can be readily mechanically separated and recycled after cleaning. It is estimated that at least 200 millions tonnes of such aged refuse are available in China alone, and at least 10 times that much is buried worldwide. Hence, the evaluation of mined landfill waste and consideration of its potential uses is of great significance.     

Analyzing nutrient distribution in different particle-size municipal aged refuse

To investigate the feasibility of using aged municipal solid waste as farmland soil, it is essential to study its nutritive compositions for plant growth. Previous studies have demonstrated that the properties of different particle-size aged refuse are very different, therefore, the present study was conducted to evaluate the adequacy of three elements (N, P, K) and the fractionation of inorganic P in the aged refuse with a particle-size distribution of 900 to 300, 300 to 150, 150 to 105, 105 to 90 and 90 to 0 μm. The results indicate that (1) total quantities of N, P, K were much larger than that in the general soil and the quantities of available N, P and K were also adequate; (2) total content of P was sufficient, but the ratio of available-P to total P was not high enough; (3) with the decrease of particle size, the contents of these elements presented different trends. The results implicate that total contents of N, P and K were enough for the aged refuse being exploited as cultivated soil, and different gradation of aged refuse could be added to improve poor soils. It provides scientific evidence for utilizing different particle-size aged refuse comprehensively.     

Size-fractionation and characterization of landfill leachate and the improvement of Cu2+ adsorption capacity in soil and aged refuse

Leachate was collected from an anaerobic lagoon at Shanghai Laogang refuse landfill, the largest landfill in China, and the sample was separated into six fractions using micro-filtration membranes, followed by ultra-filtration membranes. Several parameters of the samples were measured, including chemical oxygen demand (COD), total organic carbon (TOC), total solids (TS), pH, total phosphate (TP), total nitrogen (TN), fixed solids (FS), NH4+, orthophosphate, color, turbidity, and conductivity. These parameters were then quantitatively correlated with the molecular weight cutoff of the membrane used. Organic matter in the dissolved fraction (MW<1kDa) predominated in the leachate, accounting for 65% of TOC. Thermal infrared spectroscopy was used to characterize the filter residues. Asymmetric and symmetric stretching of methyl and methylene groups, and of functional groups containing nitrogen and oxygen atoms, were observed. In addition, the ability of two different samples to adsorb heavy metals was tested. Cu2+ was chosen as the representative heavy metal in this study, and the samples were soil; aged refuse, which had spent 8 years in a conventional sanitary landfill; and samples of soil and aged refuse treated for 48h with leachate in the ratio of 5g of sample per 50ml of leachate. Cu2+ uptake by the raw soil was approximately 4.60microg/g, while uptake by the leachate-contacted soil and leachate-contacted aged refuse were 5.66 and 5.11microg/g, respectively. These results show that the organic matter in the leachate enhanced the capacity of aqueous solutions to adsorb Cu2+.     

Mesophilic digestion of the organic fraction of refuse: Performance and kinetic study

The anaerobic digestion of the organic fraction of municipal solid waste sorted by plant was investigated in a 3 m³ stirred digester, operating under mesophilic conditions. Yields of gas obtained at 7 kg total volatile solids per m³ per day and 15-day hydraulic residence time (about 10% biodegradeable solids, 20% total solids) were as much as 1.6 times the digester volume per day. Better sorting should improve the yields which already compare favorably with the existing literature data. A kinetic study on the substrate utilization was performed by employing the “first order” model.     

Thermal-behavior study of chlorine released from composite refuse derived fuel

In order to reduce secondary pollution during the incineration of composite refuse derived fuel (CRDF), the combustion features and the emission behavior of chlorine in CRDF containing coal were analyzed. The former was analyzed using thermo-gravimetric and the latter by gas chromatography–mass spectrometry. The release rate of inorganic chlorine during combustion reached 90 mass% at temperature between 773.15 and 873.15 K. On the other hand, approximately 84 mass% release rates was resulting from pyrolysis at 723.15 K. When temperature reached above 1073.15 K, it was noticed that higher concentration of organic chlorine in different organic compounds were produced in the processing of pyrolysis compared with those released from the combustion processing. From the thermo-gravimetric analysis using a self-designed system, three distinct phases were detected in the thermal process of CRDF. The first phase occurred at temperature between 473 and 573 K and its mass loss was about 38.50%. The second phase between temperature regions of 673–773 K with a mass loss of 20.35%. The third phase was observed at the temperature between 873 and 1073 K with 22.25% mass loss.     

垃圾焚烧发电项目主要环境问题及应对措施

从项目选址、垃圾贮存、焚烧及灰渣处置等方面探讨垃圾焚烧发电项目需注意的主要环境问题,并提出相应的防治措施和建议.