改进型石灰混凝法去除城市污水二级出水中有机物的研究

将石灰混凝处理后的沉淀泥渣进行回流，对石灰混凝法进行改进，研究改进后的石灰混凝法对城市污水二级出水中有机物的去除效果。结果表明，活性泥渣回流有利于提高石灰混凝法对城市污水二级出水中有机物的去除。回流位置在石灰投加前、复合絮凝剂投加后，最佳回流量为新泥渣产生量的100％～200％，活性泥渣回流的最佳pH为11．0～11．5；活性泥渣中CaCO3、Mg(OH)2、Fe(OH)3等沉淀物以及有机高分子絮体均有助于提高其对有机物的去除效果，其中Mg(OH)2沉淀物起主导作用；含循环泥渣的活性污泥回流，对有机物的去除效果无明显影响。     

Environmental assessment of supercritical water oxidation of sewage sludge

Environmental aspects of using supercritical water oxidation (SCWO) to treat sewage sludge were studied using a life cycle assessment (LCA) methodology. The system studied is the first commercial scale SCWO plant for sewage sludge in the world, treating sludge from the municipal wastewater treatment facility in Harlingen, TX, USA. The environmental impacts were evaluated using three specific environmental attributes: global warming potential (GWP), photo-oxidant creation potential (POCP) and resource depletion; as well as two single point indicators: EPS2000 and EcoIndicator99. The LCA results show that for the described process, gas-fired preheating of the sludge is the major contributor to environmental impacts, and emissions from generating electricity for pumping and for oxygen production are also important. Overall, SCWO processing of undigested sewage sludge is an environmentally attractive technology, particularly when heat is recovered from the process. Energy-conserving measures and recovery of excess oxygen from the SCWO process should be considered for improving the sustainability potential.     

气田污泥脱水工艺研究

在对气田废水处理中产生的污泥进行处理时,普遍存在着干化周期长、含水率高等问题,严重影响了废水处理装置的处理能力。脱水剂优化选择实验以及污泥脱水性能实验结果表明:先加入聚合氯化铝并搅拌15 s,再加入阴离子聚丙烯酰胺并搅拌混合30 s,最后加入FO4190SH搅拌,混合凝聚30 s后静止分层,其凝聚效果较好。在污泥脱水性能的各项指标中,真空脱水均好于重力脱水,特别是对于新鲜污泥滤层,真空(45 kPa)脱水速度比重力脱水速度约高8倍。     

含油污泥特点及处理方法

含油污泥主要来源于油田开采、油气集输及污水处理场,污泥中一般含油率在10%～50%,含水率在40%～90%。文章介绍了不同来源含油污泥的特点及脱水方法,并对各种含油污泥处理方法的优、缺点进行了比较。研究结果表明,各种方法都有其特点和适用范围。由于含油污泥成分复杂,没有任何一种处理方法可以处理所有类型的含油污泥。     

Emerging technology for increasing glucosinolates in arugula and mustard greens

Two plant species, arugula (Eruca sativa) and mustard (Brassica juncea) were field-grown under four soil management practices: soil mixed with municipal sewage sludge (SS), soil mixed with horse manure (HM), soil mixed with chicken manure (CM), and no-mulch bare soil (NM) to investigate the impact of soil amendments on the concentration of glucosinolates (GSLs) in their shoots. GSLs, hydrophilic plant secondary metabolites in arugula and mustard were extracted using boiling methanol and separated by adsorption on sephadex ion exchange disposable pipette tips filled with DEAE, a weak base, with a net positive charge that exchange anions such as GSLs. Quantification of GSLs was based on inactivation of arugula and mustard myrosinase and liberation of the glucose moiety from the GSLs molecule by addition of standardized myrosinase (thioglucosidase) and spectrophotometric quantification of the liberated glucose moiety. Overall, GSLs concentrations were significantly greater (1287 µg g^?1 fresh shoots) in plants grown in SS compared to 929, 890, and 981 µg g^?1 fresh shoots in plants grown in CM, HM, and NM soil, respectively. Results also revealed that mustard shoots contained greater concentrations of GSLs (974 µg g^?1 fresh shoots) compared to arugula (651 µg g^?1 fresh shoots).     

Comparative assessment of municipal sewage sludge incineration,gasification and pyrolysis for a sustainable sludge-to-energy management in Greece

For a sustainable municipal sewage sludge management, not only the available technology, but also other parameters, such as policy regulations and socio-economic issues should be taken in account. In this study, the current status of both European and Greek Legislation on waste management, with a special insight in municipal sewage sludge, is presented. A SWOT analysis was further developed for comparison of pyrolysis with incineration and gasification and results are presented. Pyrolysis seems to be the optimal thermochemical treatment option compared to incineration and gasification. Sewage sludge pyrolysis is favorable for energy savings, material recovery and high added materials production, providing a ‘zero waste’ solution. Finally, identification of challenges and barriers for sewage sludge pyrolysis deployment in Greece was investigated.     

Valorisation of used cooking oil sludge by codigestion with swine manure

The addition of lipid wastes to the digestion of swine manure was studied as a means of increasing biogas production. Lipid waste was obtained from a biodiesel plant where used cooking oil is the feedstock. Digestion of this co-substrate was proposed as a way of valorising residual streams from the process of biodiesel production and to integrate the digestion process into the biorefinery concept.Batch digestion tests were performed at different co-digesting proportions obtaining as a result an increase in biogas production with the increase in the amount of co-substrate added to the mixture. Semi-continuous digestion was studied at a 7% (w/w) mass fraction of total solids. Co-digestion was successful at a hydraulic retention time (HRT) of 50 d but a decrease to 30 d resulted in a decrease in specific gas production and accumulation of volatile and long chain fatty acids. The CH₄ yield obtained was 326 ± 46 l/kg VS_feed at an HRT of 50 d, while this value was reduced to 274 ± 43 l/kg VS_feed when evaluated at an HRT of 30 d. However these values were higher than the one obtained under batch conditions (266 ± 40 l/kg VS_feed), thus indicating the need of acclimation to the co-substrate. Despite of operating at low organic loading rate (OLR), measurements from respirometry assays of digestate samples (at an HRT of 50 d) suggested that the effluent could not be directly applied to the soil as fertiliser and might have a negative effect over soil or crops.     

Co-treatment of fruit and vegetable waste in sludge digesters. An analysis of the relationship among bio-methane generation,process stability and digestate phytotoxicity

The co-digestion of a variable amount of fruit and vegetable waste in a waste mixed sludge digester was investigated using a pilot scale apparatus. The organic loading rate (OLR) was increased from 1.46 kg VS/m³ day to 2.8 kg VS/m³ day. The hydraulic retention time was reduced from 14 days to about 10 days. Specific bio-methane production increased from about 90 NL/kg VS to the maximum value of about 430 NL/kg VS when OLR was increased from 1.46 kg VS/m³ day to 2.1 kg VS/m³ day. A higher OLR caused an excessive reduction in the hydraulic retention time, enhancing microorganism wash out. Process stability evaluated by the total volatile fatty acids concentration (mg/l) to the alkalinity buffer capacity (eq. mg/l CaCO₃) ratio (i.e. FOS/TAC) criterion was <0.1 indicating high stability for OLR <2.46 kg VS/m³ day. For higher OLR, FOS/TAC increased rapidly. Residual phytotoxicty of the digestate evaluated by the germination index (GI) (%) was quite constant for OLR < 2.46 kg VS/m³ day, which is lower than the 60% limit, indicating an acceptable toxicity level for crops. For OLR > 2.46 kg VS/m³ day, GI decreased rapidly. This corresponding trend between FOS/TAC and GI was further investigated by the definition of the GI ratio (GIR) parameter. Comparison between GIR and FOS/TAC suggests that GI could be a suitable criterion for evaluating process stability.     

BMP tests of source selected OFMSW to evaluate anaerobic codigestion with sewage sludge

The aim of this study is to characterize different types of source selected organic fraction of municipal solid waste (SS-OFMSW) in order to optimize the upgrade of a sewage sludge anaerobic digestion unit by codigestion. Various SS-OFMSW samples were collected from canteens, supermarkets, restaurants, households, fruit–vegetable markets and bakery shops. The substrates characterization was carried out getting traditional chemical–physical parameters, performing elemental analysis and measuring fundamental anaerobic digestion macromolecular compounds such as carbohydrates, proteins, lipids and volatile fatty acids. Biochemical methane potential (BMP) tests were conducted at mesophilic temperature both on single substrates and in codigestion regime with different substrates mixing ratios. The maximum methane yield was observed for restaurant (675 NmlCH₄/gVS) and canteens organic wastes (571 and 645 NmlCH₄/gVS). The best codigestion BMP test has highlighted an increase of 47% in methane production respect sewage sludge digestion.     

SBR加载不同粒径磁性活性炭对其污泥颗粒化进程的影响机制

在相同序批式活性污泥反应器(SBR)中分别加载1.5 g·L~(-1)的80、140、200、和300目不同粒径的磁性活性炭(反应器编号依次为2、3、4、5号),同时以不投加磁性活性炭的SBR反应器(1号)作为对照组,研究各反应器污泥体积指数(SVI)、粒径分布特征、胞外聚合物(EPS)中胞外蛋白(PN)、胞外多糖(PS)的含量变化规律以及除污性能.结果表明,不同粒径磁性活性炭对污泥颗粒化进程有一定的影响,粒径过大、过小对促进污泥颗粒化进程的强化作用不明显,当磁性活性炭的粒径为140目和200目时,活性污泥很容易以其作为"成核"载体快速形成好氧颗粒污泥,并且形成的颗粒污泥结构紧密,沉降速率快.采用高斯函数分析污泥粒径分布和标准偏差发现,反应器运行的第50 d,3号和4号反应器内污泥平均粒径均达到了780μm以上,明显高于其他反应器,标准偏差分别为318.9μm和362.3μm,两反应器内形成的颗粒污泥粒径较均匀,处理系统较稳定.与此同时,投加不同粒径的磁性活性炭均有利于促进污泥胞外蛋白质PN含量的增加,对胞外多糖PS的含量影响不大;但合适的磁性活性炭粒径(140目和200目)越有利于污泥PN的分泌,颗粒化程度明显的3号和4号反应器的PN/PS比值均高于其他3个反应器.磁性炭基好氧颗粒污泥的形成符合"惰性内核模型".此外,3号、4号反应器对废水TN和TP的去除率分别达到50%和60%以上,均高于其他反应器.