清洁生产纳入环境影响评价的意义

当前的环境影响评价在某种程度上更侧重于环境的末端治理,无法将污染控制与生产过程控制密切结合,资源和能源不能在生产过程中得到充分利用.而清洁生产在这方面却有着独特的特点和优势.根据清洁生产与环境影响评价的内在联系,尽快地将清洁生产纳入环境影响评价是具有重要意义的,清洁生产应该成为环境影响评价报告撰写中的重要内容.     

Ultrasound pretreatment of filamentous algal biomass for enhanced biogas production

The filamentous alga Hydrodictyon reticulatum harvested from a bench-scale wastewater treatment pond was used to evaluate biogas production after ultrasound pretreatment. The effects of ultrasound pretreatment at a range of 10–5000 J/mL were tested with harvested H. reticulatum. Cell disruption by ultrasound was successful and showed a higher degree of disintegration at a higher applied energy. The range of 10–5000 J/mL ultrasound was able to disintegrated H. reticulatum and the soluble COD was increased from 250 mg/L to 1000 mg/L at 2500 J/mL. The disintegrated algal biomass was digested for biogas production in batch experiments. Both cumulative gas generation and volatile solids reduction data were obtained during the digestion. Cell disintegration due to ultrasound pretreatment increased the specific biogas production and degradation rates. Using the ultrasound approach, the specific methane production at a dose of 40 J/mL increased up to 384 mL/g-VS fed that was 2.3 times higher than the untreated sample. For disintegrated samples, the volatile solids reduction was greater with increased energy input, and the degradation increased slightly to 67% at a dose of 50 J/mL. The results also indicate that disintegration of the algal cells is the essential step for efficient anaerobic digestion of algal biomass.     

Optimization of micro-aeration intensity in acidogenic reactor of a two-phase anaerobic digester treating food waste

Micro-aeration is known to promote the activities of hydrolytic exo-enzymes and used as a strategy to improve the hydrolysis of particulate substrate. The effect of different micro-aeration rates, 0, 129, 258, and 387 L-air/kg TS/d (denoted as LBR-AN, LBR-6h, LBR-3h and LBR-2h, respectively) on the solubilization of food waste was evaluated at 35 °C in four leach bed reactors (LBR) coupled with methanogenic upflow anaerobic sludge blanket (UASB) reactor. Results indicate that the intensity of micro-aeration influenced the hydrolysis and methane yield. Adequate micro-aeration intensity in LBR-3h and LBR-2h significantly enhanced the carbohydrate and protein hydrolysis by 21–27% and 38–64% respectively. Due to the accelerated acidogenesis, more than 3-fold of acetic acid and butyric acid were produced in LBR-3h as compared to the anaerobic treatment LBR-AN resulting in the maximum methane yield of 0.27 L CH₄/g VS_added in the UASB. The performance of LBR-6h with inadequate aeration was similar to that of LBR-AN with a comparable hydrolysis degree. Nevertheless, higher aeration intensity in LBR-2h was also unfavorable for methane yield due to significant biomass generation and CO₂ respiration of up to 18.5% and 32.8% of the total soluble hydrolysate, respectively. To conclude, appropriate micro-aeration rate can promote the hydrolysis of solid organic waste and methane yield without undesirable carbon loss and an aeration intensity of 258 L-air/kg TS/d is recommended for acidogenic LBR treating food waste.     

Full-scale blending treatment of fresh MSWI leachate with municipal wastewater in a wastewater treatment plant

Fresh leachate, generated in municipal solid waste incineration (MSWI) plants, contains various pollutants with extremely high strength organics, which usually requires expensive and complex treatment processes. This study investigated the feasibility of blending treatment of MSWI leachate with municipal wastewater. Fresh MSWI leachate was pretreated by coagulation–flocculation with FeCl₃ 2 g/L and CaO 25 g/L, plate-and-frame filter press, followed by ammonia stripping at pH above 12. After that, blending treatment was carried out in a full-scale municipal wastewater treatment plant (WWTP) for approximately 3 months. Different operational modes consisting of different pretreated leachate and methanol addition levels were tested, and their performances were evaluated. Results showed that throughout the experimental period, monitored parameters in the WWTP effluent, including COD (<60 mg/L), BOD₅ (<20 mg/L), ammonium (<8 mg/L), phosphorus (<1.5 mg/L) and heavy metals, generally complied with the Chinese sewage discharged standard. Under the experimental conditions, a certain amount of methanol was needed to fulfill TN removal. An estimation of the operation cost revealed that the expenditure of blending treatment was much lower than the total costs of respective treatment of MSWI leachate and municipal wastewater. The outcomes indicated that blending treatment could not only improve the treatability of the MSWI leachate, but also reduce the treatment cost of the two different wastewaters.     

Enterotoxin production and antimicrobial susceptibility in Staphylococci isolated from traditional raw milk cheeses in Serbia

This study was undertaken to determine the prevalence of coagulase positive staphylococci (CPS) by examining a total of 71 raw milk cheeses. Additionally, enterotoxigenicity, antimicrobial susceptibility and the presence of mecA and mecC genes in the staphylococcal isolates were investigated. The isolation and enumeration procedure of CPS followed the International Organization for Standardization (ISO) standard. The presumptive staphylococci were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) using the VITEK MS system. VIDAS® Staph enterotoxin II assay was used for the detection of classical enterotoxins. Antimicrobial susceptibility testing (AST) was accomplished performing the disk diffusion method. All suspected methicillin resistant staphylococci were investigated for the presence of mecA and mecC genes by PCR assay. A high prevalence (87.32%) of CPS was detected in the cheeses at contamination levels up to 5.58 log CFU g^?1. Among 47 staphylococcal isolates screened for enterotoxin production, only one isolate, identified as S. hyicus, was confirmed as being enterotoxigenic. Resistance to penicillin (63.70%) was the most common resistance among the tested Staphylococcus aureus isolates. The dominant phenotypic resistance patterns in coagulase negative staphylococci (CNS) were resistance to ofloxacin and fusidic acid. All CNS isolates were susceptible to the clinically important antibiotics clindamycin, chloramphenicol, gentamicin, linezolid, rifampicin and trimethoprim-sulfamethoxazole. The mecA and mecC genes were not detected. To the best of our knowledge, this is the first study concerning evaluation of the presence of methicillin resistant staphylococci (MRS) in dairy products in Serbia.     

ABR-生物接触氧化法处理果汁废水实验分析

厌氧式折流反应器(Anaerobic Baffled Reactor,简称ABR)是一种新型高效厌氧反应器,具有工艺技术简单、建设投资费用低、运行管理方便、固液分离效果好、出水水质好、运行稳定可靠、对有毒物质适应性强等优点,是一种极具开发应用前景的废水生物处理新技术。ABR最大的特点是在反应器中设置上下折流板而在水流方向上形成依次串联的隔室,从而使其中的微生物种群沿长度方向的不同隔室实现产酸和产甲烷相的分离。该反应器具有结构简单,截留污泥能力强,系统处理效果稳定,运行管理方便等优点。分析了ABR及ABR与其它工艺的联合在果汁废水处理方面的应用。     

电化学氢化物发生法处理含锑废水及对锑的回收

采用电化学氢化物发生法对模拟含锑废水进行处理,锑与水电解产生的氢形成氢化物从溶液中脱除,而后收集并加热分解锑化氢得到金属锑.实验表明,在酸性条件下对Sb(Ⅲ)去除效果较好,p H=4时去除率为76.1%.Sb(Ⅲ)与电解水产生的氢结合形成锑化氢从溶液中逸出是溶液中锑去除的最主要途径(回收率为66.2%),电沉积和吸附也对锑的去除做出少量贡献.Sb(Ⅴ)须预还原为Sb(Ⅲ)再氢化进行去除.试用了铅、石墨、钨这3种电解阴极材料,铅电极处理效果最佳.     

容积负荷对ABR-MBR工艺反硝化除磷性能的影响

采用连续流ABR-MBR组合工艺处理生活污水,研究不同容积负荷(volume loading rate,VLR)对该工艺反硝化除磷性能的影响,获得最佳工艺参数.试验考察ABR进水容积负荷(以COD计,下同)分别为0.76、1.01、1.51和2.27 kg·(m~3·d)~(-1)时系统去碳脱氮除磷的性能,并在各ABR容积负荷条件下考察MBR容积负荷对MBR反应器硝化性能的影响.结果表明,在ABR进水容积负荷为1.51 kg·(m~3·d)~(-1)的条件下,系统A2隔室COD去除量最大,并在MBR容积负荷为0.462 kg·(m~3·d)~(-1)时,MBR反应器中实现了短程硝化,系统NH_4~+-N和TN去除率分别达到90%和72%以上,厌氧释磷量为7.41 mg·L~(-1),缺氧吸磷量达到15.42 mg·L~(-1),出水PO_4~(3-)-P浓度低于0.5 mg·L~(-1),这表明短程硝化更有利于强化ABR-MBR系统的反硝化除磷性能.     

典型城市污水中对羟基苯甲酸酯的污染特征

对羟基苯甲酸酯(parabens)作为防腐剂、防霉剂和杀菌剂等被广泛应用于食品、化妆品和药品中.近年来的研究表明,该类化合物能够在地表水体中检出,对水生生态环境存在潜在的危害.本研究于2016年秋季和冬季,对哈尔滨某典型城市污水处理厂进水进行了24 h连续采集,对6种parabens的质量浓度和4种常规水质指标进行了分析.结果表明,parabens普遍存在于城市污水中,对羟基苯甲酸甲酯、对羟基苯甲酸乙酯和对羟基苯甲酸丙酯是主要目标物,总有机碳、总溶解固体和酸碱度与parabens的浓度具有相关性;城市污水中parabens的质量浓度具有明显的日变化趋势,但是季节差异性不大.本研究结果为城市污水处理系统中parabens的深入研究和污染控制提供了重要理论依据.     

Fenton法处理竹制品废水生化出水的研究

采用Fenton法对竹制品废水生化出水的脱色和有机物去除进行了研究.在综合考虑经济性和去除效果的基础上,起始COD质量浓度为430 mg·L-1、色度为1 500倍的废水,在反应条件:t=30℃,pH为3.5,ρ(H2O2)=1 665 mg·L-1,c(Fe2+)/c(H2O2)=0.072,反应时间3 h的情况下,Fenton氧化处理后,COD和色度的去除率分别高达87.5%和94.4%.研究发现,色度的去除率要优于有机物(以COD计)的去除率,且受外界因素影响小.GC-MS分析结果表明:经过Fenton处理后,废水中的发色团和助色团基本上完全被去除.中间产物主要是脂类衍生物,副产品有1-碘十三烷和正辛基醚等.