嘉兴垃圾填埋场渗滤液的土柱淋滤实验研究

通过室内淋滤实验分析垃圾渗滤液-水-岩相互作用过程。实验发现Cl-的保守性是相对的,其中在粉砂土中Cl-存在吸附解吸现象,平衡浓度为4446mg/L时,分配系数Kd=0.18L/kg,而在壤土(亚粘土)中Cl-保持保守。SO42-和F-积极参与水岩相互作用,粉砂土和壤土对SO42-和F-均有较强的吸附作用。阴离子交换作用的结果使大量的NO 3-从粉砂土中解吸出来。     

Anaerobic digestion of the organic fraction of municipal solid waste: influence of co-digestion with manure

Anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) was investigated in two thermophilic (55 degrees C) wet digestion treatment systems R1 and R2. Initially OFMSW was co-digested with manure with a successively higher concentration of OFMSW, at a hydraulic retention time (HRT) of 14-18 d and an organic loading rate (OLR) of 3.3-4.0 g-VS/l/d. Adaptation of the co-digestion process to a OFMSW:manure ratio of 50% (VS/VS) was established over a period of 6 weeks. This co-digestion ratio was maintained in reactor R2 while the ratio of OFMSW to manure was slowly increased to 100% in reactor R1 over a period of 8 weeks. Use of recirculated process liquid to adjust the organic loading to R1 was found to have a beneficial stabilization effect. The pH rose to a value of 8 and the reactor showed stable performance with high biogas yield and low VFA levels. The biogas yield from source-sorted OFMSW was 0.63-0.71 l/g-VS both in the co-digestion configuration and in the treatment of 100% OFMSW with process liquid recirculation. This yield is corresponding to 180-220 m3 biogas per ton OFMSW. VS reduction of 69-74% was achieved when treating 100% OFMSW. None of the processes showed signs of inhibition at the free ammonia concentration of 0.45-0.62 g-N/l.     

Electrolysis of soluble organic matter in leachate from landfills

Laboratory experiments were conducted to investigate the effectiveness of electro-chemical methods for treating leachates from municipal garbage landfills. Chemical oxygen demand (COD) removal range from 30 to 50% were obtained with a batch electro-chemical reactor using two different electrode pairs, Fe---Cu or Al---Cu. Both electrolysis and electro-coagulation were observed for the removal of the organic matter in the leachates, with the former mechanism being the dominant in this investigation. The organic matters were found to be electrolyzed at an applied voltage as low as 2.0 V. IR spectra analyses of treated leachates confirmed that intense oxidation took place throughout the electro-chemical experiments.     

The influence of weathering and organic matter on heavy metals lability in silicatic, Alpine soils

We investigated the effect of organic matter and weathering on the lability and solid phase speciation of heavy metals (Cd, Cr, Cu, Ni, Pb, Zn) in two contrasting subalpine regions in the Italian Alps. Cr, Ni and Cu could be linked to weathering. This was not the case for Pb. Since organic matter (OM) influences the solid phase speciation of heavy metals, the total organic C and N content, the C and N content of different density fractions of OM and also of the labile (oxidised by H₂O₂) and stable (H₂O₂-resistant) fractions were determined. Soil OM stocks were high and soils on north-facing slopes had more OM than the south-facing sites to which they were paired. Density measurements and the H₂O₂ fractionation indicated that the higher OM content on north-facing sites was due to an accumulation of weakly degraded organic material. Due to higher weathering intensity on north-facing sites, the abundance of the EDTA-extractable heavy metals was higher than on south-facing sites. All EDTA-extractable heavy metals showed a good correlation to the water-soluble phenolic concentrations which indicates that the metals were probably translocated as metal-organic complexes. Pb and Cu correlate not only to the light (density < 1 g/cm³) and labile, organic fraction but also to the heavy (density > 2 g/cm³) and stable fraction. High-mountain ecosystems like the Alps are sensitive to changing environmental conditions such as global warming. A warmer climate and the more favourable conditions it brings for biological activity, especially at cooler sites, will probably lead in the short- to mid-term to an increased loss of accumulated, weakly degraded OM. As the Pb and Cu content is significantly related to the labile organic matter pools, the risk exists that an increase in OM mineralisation could affect the storage capacity and mobility of these metals in soils.     

掺烧城市垃圾残渣硅酸盐水泥性能及重金属浸出行为研究

通过生料易烧性试验、熟料矿物岩相分析、XRD、SEM、水泥胶砂强度试验、重金属离子浸出试验等,对利用城市垃圾分拣残渣配料煅烧硅酸盐水泥熟料及其水化反应的特征进行了研究。结果表明:城市垃圾分拣残渣配料制成的水泥熟料,其矿物结构与常规的硅酸盐水泥熟料相同;其烧成温度有降低的趋势;其水化产物和凝结硬化过程与常规硅酸盐水泥相同;熟料煅烧和凝结硬化过程对城市垃圾中重金属离子的固化有一定的辅助作用。     

Aging of air pollution control residues from municipal solid waste incinerator: role of water content on metal carbonation

This work studies the effect of water content on the aging of APC residues, with a liquid to solid ratio (L/S) of 0.25 or 10, aged with or without exposure to ambient air. After the residue was mixed with water, CaSO4 and (Na,K)Al3(SO4)2(OH)6 in the raw sample yielded ettringite. When CO2 were available, this ettringite was further transformed to gypsum, calcite and possibly gibbsite. Experimental data revealed that the concentrations of Pb, Zn, Cd, Hg, and Cu fell with age, whereas that of Cr increased. Given L/S=10, excess Ca2+ ions were present in the suspension, so a precipitate of primarily calcite crystals of sizes under 5 microm formed on the air-water surface. This layer significantly reduced the rates of decline of Pb, Zn, Cd and Hg contents, and also reduced the increasing rate of Cr content in the suspension. This result follows from the mass transfer barrier of CO2 added at the air-water surface and the occurrence of subsequent chemical reactions in the suspension. An estimate of the mass transfer rate revealed that the rate-controlling step with L/S=10 was the dissolution and diffusion of CO2 in the bulk solution. However, at L/S=0.25, the rate-limiting step was the dissolution of metals from ash particles. Water content is a very important process factor, whose distribution in the sample, and the resulting competition between carbonate ion flux and heavy metal flux, govern the reaction time required during the natural aging process.     

废弃混凝土中重金属浸出性研究

以我国现有废弃混凝土为原料,研究废弃混凝土中重金属含量,采用模拟德国水槽试验法,以不同粒径、不同pH值、不同重金属元素(Cd、Cr、Cu、Ni、Pb、Z)为影响因素,研究废弃混凝土中重金属离子的浸出性,结果表明,废弃混凝土中不同重金属含量不同,以Zn含量最高,Cr含量最低;粒径在1mm以上时随着粒径增加重金属浸出性减小...     

Arsenic speciation and mobilization in CCA-contaminated soils: influence of organic matter content

A laboratory incubation experiment was conducted to investigate the influence of organic matter content on arsenic speciation and mobilization in chromated copper arsenate (CCA)-contaminated soils. The study was performed with four synthetic CCA-contaminated soils, with a range of organic matter content (mixture of peat moss and poultry manure) varying between 0.5% and 15% (w/w), under unsaturated and aerobic conditions for 40 days. Changes in water-soluble arsenic speciation (As(V), As(III), MMAA, DMAA) were monitored over time in soil extracts by HPLC-ICP-MS and in the soil solid phase (As(III), As(V)) by a solvent extraction method. Irrespective of organic matter content, As(V) was the predominant soil bound and aqueous phase arsenic species. However, over 40 days, a high soil organic matter content (7.5% and 15%) was able to entail formation of soil bound As(III). Moreover, total water-soluble arsenic was positively correlated with dissolved organic carbon (r(2)=0.88). However, the organic matter content did not influence arsenic speciation in the soluble fraction; neither As(V) reduction nor arsenic biomethylation occurred within 40 days. An increase in dissolved organic carbon content promoted both As(V) and As(III) solubilization in soils. Also, over time, organic matter contents of 7.5% and 15% entailed the persistence of soluble As(V), likely due to the high content of dissolved organic compounds which prevented its sorption onto soil. Based on this data, the environmental risk of aerobic CCA-contaminated soils rich in organic matter may be due to an enhanced availability of soluble As(V) over time, rather than to the formation of the more toxic and more mobile As(III).     

生活垃圾焚烧炉渣制备免烧墙体砖对环境负荷的影响

运用生命周期评价法,以试验和生产数据为基础,参考有关统计数据及资料,对利用生活垃圾焚烧炉渣制备免烧墙体砖、灰砂砖及烧结砖进行比较分析,探讨功能单位墙体砖制备过程及与其相关的原料开采、原油生产、电力生产和煤炭生产过程对环境负荷的影响.结果表明,功能单位焚烧炉渣免烧墙体砖、灰砂砖和烧结砖的环境负荷分别为3.51x10-12/a.3.58x10-12/a和6.60x10-12/a;生活垃圾焚烧炉渣免烧墙体砖与烧结砖相比,可减少不可再生资源消耗54%,与灰砂砖和烧结砖相比,可分别减少不可再生能源消耗43%和62%.     

Characterization of soluble organic matter of waste activated sludge before and after thermal pretreatment

Microwave (MW) irradiation and conventional heating (CH) at 96 °C was successful in disrupting the complex waste activated sludge (WAS) floc structure and releasing extra- and intra-cellular biopolymers, such as protein and sugars from activated sludge flocs into soluble phase along with solubilization of particulate chemical oxygen demand (COD). Soluble CODs of CH and MW-irradiated WAS were 361±45% and 143±34% higher and resulted in 475±3% and 211±2% higher cumulative biogas productions (CBP) relative to the control at the end of 23 days of mesophilic anaerobic digestion, respectively. Ultrafiltration (UF) was used to characterize the soluble molecular weight (Mw) distributions of control (unpretreated), CH and MW-irradiated WAS. Depending on the Mw fraction, the range of substrate volumetric utilization rate increases from anaerobic digesters was between 94% and 84% for CH and 26–113% for MW compared to the control for the first nine days of the digestion. Digesters treating high Mw (>300 kDa) materials resulted in smaller biodegradation rate constants, k, indicating that microorganisms require a longer time to utilize high Mw fractions which are most likely cell wall fragments and exopolymers.     

Changes in organic matter and residual effect of amendment with two-phase olive-mill waste on degraded agricultural soils

Agricultural soils from many parts of the Mediterranean region are very poor in organic matter and are exposed to progressive degradation processes. Therefore, additions of the olive-mill waste from a continuous two-phase system as an organic amendment can improve soil quality and hence mitigate the negative environmental and agronomic limitations of these soils. A field study under semiarid Mediterranean conditions was conducted to evaluate the changes in organic matter after four consecutive annual additions of olive-mill watery husk (OMWH) waste and the de-oiled two-phase olive pomace (TPOP) waste on an olive grove soil: a cutanic Luvisol (CL). Treatments included a control, OMWH (30 and 60 Mg ha(-1), DW equivalent), and TPOP (27 and 54 Mg ha(-1), DW equivalent). Also, a two-year greenhouse study using wheat (Triticum aestivum L.) was conducted to evaluate the residual effects of adding OMWH to CL soil and to a degraded Leptic Cambisol (LC). Treatments included five OMWH rates ranging from 0 to 40 Mg ha(-1). Significant increases in total organic carbon (TOC), water soluble organic carbon (WSOC), humic and fulvic acids, and aggregate stability were observed in the treated plots, and the highest humification index was obtained when OMWH was applied at the lowest rate. The increase in aggregate stability correlated positively and highly significantly (P<0.01) with the humic and fulvic acid and WSOC contents. In the greenhouse, significant increases in TOC, carbohydrates, aggregate stability, total N, available K, and cation exchange capacity were observed in both soils. However, available P decreased significantly. There was an increased residual fertilization effect of OMWH for both soils. The best fits to grain yield and OMWH rates were with a linear regression for the CL soil (R(2)=0.957 and P<0.01), and a quadratic regression for the LC soil (R(2)=0.960 and P<0.01).     

The influence of spent household batteries to the organic fraction of municipal solid wastes during composting

The objective of this work was to investigate the potential transfer of 9 heavy metals from spent household batteries (zinc-carbon and alkaline-manganese batteries) to the organic fraction of municipal solid wastes during active composting. Six runs were performed including one control and 2 replications. Eleven types of alkaline and non-alkaline batteries were added at 3 different levels to the organic fraction of municipal solid wastes, namely at percentages equal to 0.98% w/w (low), 5.2% w/w (medium) and 10.6% w/w (high). Experiments were performed in 230 l insulated plastic aerobic bioreactors under a dynamic air flow regime for up to 60 days. Iron, copper and nickel masses contained in the organic fraction of the wastes were found significantly higher in the high level runs compared to the corresponding masses in the control. No metal transfer was obtained in the low and medium level runs. Metal mass balance closures ranged from 51% to 176%. Metals' concentrations in the leachates were below 10 mg l⁻¹ for most metals, except iron, while an increasing concentration trend versus time was measured in the leachates of the high level runs. In all cases, the contents of 5 regulated heavy metals in all end products were below the Hellenic limits.     

重庆市城市生活垃圾的蠕变特性研究

首先以分别加载的方式对以重庆市城市生活垃圾典型组分为依据配制的垃圾试样进行不同应力水平的室内压缩蠕变试验,进而根据蠕变元件的基本性质和试验过程中试样反映出的变形特征,利用HK和PTH蠕变模型对生活垃圾的蠕变曲线进行拟合,并总结得出蠕变模型的基本参数。研究表明,HK和PTH模型对试验数据的拟合程度都比较好,此两种模型对于垃圾填埋场的容量计算和沉降规律研究具有一定的参考价值。     

Bioreactivity of leachate from municipal solid waste landfills - assessment of toxicity

With the UK producing 400 million tonnes of waste each year, the problem of waste disposal is recognised as one of the most serious environmental problems facing the nation. Of this, over 35 million tonnes is municipal waste, largely derived from households, but also includes some commercial and industrial waste. There are strong national and international concerns about the possible adverse health effects of living in the vicinity of municipal waste landfills. An understanding of the ranges of toxicity of landfill emissions is crucial to determine the degree of concern we should have about the potential effects they could have upon nearby populations and the surrounding environment. Leachates from three different types of landfills have been collected and screened for their potential to induce toxicity. Bioreactivity was measured by a plasmid DNA scission assay (PSA), and 2',7'-dichlorodihydrofluorescin fluorescence (DCFH). The results indicate that leachates cause damage to plasmid DNA in a dose-dependent manner and that toxicity varies between different types of landfills as well as within individual waste sites. Overall, the data implies that the complex chemistry involved in leachate formation has yet to be delineated in terms of the toxicological response.     

Evaluation on speciation and removal efficiencies of mercury from municipal solid waste incinerators in Taiwan

Two large-scale municipal solid waste incinerators (MWIs) located in Taiwan were selected for conducting flue gas sampling to determine the chemical speciation of mercury by both USEPA Method 29 and Ontario Hydro Method (OHM). In addition, the emission characteristics and removal efficiencies of mercury were evaluated via isokinetic sampling of flue gas upstream and downstream of APCDs. Results indicated that the average removal efficiencies of Hg for MWI-A and MWI-B were 29.56 and 44.70%, respectively. In terms of mercury speciation by USEPA Method 29 and Ontario Hydro Method (OHM), oxidized mercury (Hg2+), in the flue gas was predominant at the inlet of APCD for both incinerators. Less than 30% of mercury in the flue gas existed in the elemental form (Hg0) at APCD inlet. Mercury emitted from the stack also predominated as a form of Hg2+ in MWI-A. Approximately 90% of total mercury emission from the stack existed in the form of Hg2+ for MWI-A. Due to the higher removal efficiency of soluble mercury (Hg2+) in wet scrubber, less total Hg was actually emitted from MWI-B than MWI-A. Regarding the removal efficiency of Hg0 in the flue gas, the APCDs of MWI-A (DSI + FF) had a higher removal efficiency than that of MWI-B (ESP + WS) possibly due to the reduction of Hg2+ which occurred in the wet scrubber.     

Sludge heat treatment after treatment of drainage wastewater from municipal solid waste landfills

The process of calcium oxide regeneration from the sludge left after treating landfill drainage wastewater was studied. It was found that calcium oxide can be regenerated from sludge by means of heat treatment in electric furnaces within three hours at 700°C and 1.5 kW power consumption per 1 kg of sludge. It was shown that calcium oxide regenerated from sludge was not inferior in quality to commercial one and may be reused in technological process.     

有机质含量对水泥土强度的影响及对策

采用有机质含量比较高的盐城泻湖相软土进行了大量的水泥土加固室内试验，并对试验结果进行了分析，得到了强度随龄期增长的公式，并探讨了有机质对强度的不利影响，提出了抵抗有机质含量对水泥土强度影响的对策。     

Size charge fractionation of metals in municipal solid waste landfill leachate

Municipal solid waste landfill leachates from 9 Norwegian sites were size charge fractionated in the field, to obtain three fractions: particulate and colloidal matter >0.45microm, free anions/non-labile complexes <0.45microm and free cations/labile complexes <0.45microm. The fractionation showed that Cd and Zn, and especially Cu and Pb, were present to a large degree (63-98%) as particulate and colloidal matter >0.45microm. Cr, Co and Ni were on the contrary present mostly as non-labile complexes (69-79%) <0.45microm. The major cations Ca, Mg, K, and Mn were present mainly as free cations/labile complexes <0.45microm, while As and Mo were present to a large degree (70-90%) as free anions/non-labile complexes <0.45microm. Aluminium was present mainly as particulate and colloidal matter >0.45microm. The particulate and colloidal matter >0.45microm was mainly inorganic; indicating that the metals present in this fraction were bound as inorganic compounds. The fractionation gives important information on the mobility and potential bioavailability of the metals investigated, in contrast to the total metal concentrations usually reported. To study possible changes in respective metal species in leachate in aerated sedimentation tanks, freshly sampled leachate was stored for 48h, and subsequently fractionated. This showed that the free heavy metals are partly immobilized during storage of leachate with oxygen available. The largest effects were found for Cd and Zn. The proportion of As and Cr present as particulate matter or colloids >0.45microm also increased.     

Continuous treatment of the organic fraction of municipal solid waste in an anaerobic two-stage membrane process with liquid recycle

The stability and performance of a two-stage anaerobic membrane process was investigated at different organic loading rates (OLRs) and Hydraulic Retention Times (HRTs) over 200 days. The Hydrolytic Reactor (HR) was fed with the Organic Fraction of Municipal Solid Waste (OFMSW), while the leachate from the HR was fed continuously to two Submerged Anaerobic Membrane Bioreactors (SAMBR1 and 2). The Total COD (TCOD) of the leachate varied over a wide range, typically between 4000 and 26,000 mg/L while the Soluble COD (SCOD) in the permeate was in the range 400-600 mg/L, achieving a COD removal greater than 90% at a HRT of 1.6-2.3 days in SAMBR1. The operation was not sustainable below this HRT due to a membrane flux limitation at 0.5-0.8 L/m² h (LMH), which was linked to the increasing MLTSS. SCOD in the recycled permeate did not build up indicating a slow degradation of recalcitrants over time. SAMBR2 was run in parallel with SAMBR1 but its permeate was treated aerobically in an Aerobic Membrane Bioreactor (AMBR). The AMBR acted as a COD-polishing and ammonia removal step. About 26% of the recalcitrant SCOD from SAMBR2 could be aerobically degraded in the AMBR. In addition, 97.7 % of the ammonia-nitrogen was converted to nitrate in the AMBR at a maximum nitrogen-loading rate of 0.18 kg NH₄⁺-N/m³ day. GC-MS analysis was performed on the reactor effluents to determine their composition and what compounds were recalcitrant.     

Studies on the detection of salmonellae in municipal solid waste and incinerator residue

Significant factors in recovering Salmonella organisms from solid waste/sludge mixture, municipal solid waste, and incinerator residue and quench water were sample weight, number of samples, enrichment and subculture media, and incubation temperature. The optimal sample weight was 30 g; the optimal incubation temperature of inoculated enrichment medium, 39.5°C. The two enrichment media, Selenite F and Selenite brilliant green/sulfa, were equally efficient. The plating media were also important; best results were obtained with salmonella/shigella agar. Field studies conducted at four municipal incinerators of different operational design indicated that when enteric pathogens are present in the solid waste they can survive the incineration process.