Trophic transfer of mercury and methylmercury in an aquatic ecosystem impacted by municipal sewage e uents in Beijing, China

Gaobeidian Lake, located in Beijing, China, serves as a recipient lake for e uents from a large municipal sewage treatment plant (MSTP). In order to evaluate the e ects of discharging MSTP e uent on the mercury contamination of the local aquatic ecosystem, sediment cores, water, plankton, fish, and turtle samples were collected from Gaobeidian Lake for mercury speciation analysis. High concentrations of total mercury (T-Hg) were detected in sediment cores (5.24–17.0 g/g dry weight (dw), average: 10.1 g/g). The ratio of methylmercury (MeHg) to T-Hg was less than 0.3% in sediments and ranged from 35% to 76% in biota samples. The highest level of T-Hg and MeHg were found in aquatic bryophyte and crucian carp (3673 and 437 ng/g dw, respectively). The relative contents of MeHg were significantly correlated with trophic levels (R2 = 0.5506, p < 0.001), which confirmed that MeHg can be bio-transferred and biomagnified via food chain in this aquatic ecosystem.     

污泥土地利用中重金属铜在土壤中的迁移行为

研究通过模拟土柱淋溶实验来研究污泥土地利用中重金属铜在土壤中的迁移行为。结果表明污泥土地利用会明显增加土壤中铜的总量,但大部分集中在40 cm以上的土壤中。通过BCR连续提取法发现,经淋溶后耕作层（0 cm~30 cm）土壤中的铜仍然以残渣态为主（占50%以上）,但能被植物利用的酸溶/可交换态和可还原态铜有了明显的增加。与去离子水相比,模拟酸雨（pH=4.5）会使土壤中铜的淋溶强度增加,并更能促使其向下迁移。     

路面雨水主要污染物排污速率计算方法及应用

对影响路面雨水主要污染物排污速率的因素作了分析,研究和探讨了从污染源确定排污速率的方法。在实践中应用此方法进行路面雨水污染物的计算,取得了比较理想的效果。     

Effects of 5-year application of municipal solid waste compost on the distribution and mobility of heavy metals in a Tunisian calcareous soil

It is obvious that the application of solid waste compost improves the soil fertility. These wastes, however, may also have some negative effects on the agricultural environment due to their metal content. This research aimed at evaluating the influence of Tunisian municipal solid waste compost and farmyard manure on some chemical properties and the distribution of heavy metals in a calcareous Tunisian soil (clayey–loamy soil). A field plot experiment, without vegetation, was installed since 1999 at the experimental farm of the Agronomic National Institute of Tunis (INAT) in the region of Mornag (20 km south of Tunis, Tunisia). During 5 years, the field received yearly the following treatments: 0, 40, 80 and 120 t/ha of municipal solid waste compost and 0, 40 and 120 t/ha of manure. The fractionation of heavy metals in the soil was evaluated after 5 years using a sequential extraction procedure. The application of the two amendments was found to increase the content of organic matter, the total nitrogen content and the electrical conductivity, whereas it slightly decreased the soil pH. The addition of manure did not have a significant effect on the accumulation of heavy metals in the soil, whereas compost application increased the total concentration of heavy metals in the soil. The distribution of heavy metals between the different fractions in untreated and treated soils showed the residual fraction to be dominant, followed by the fraction bound to Fe and Mn oxides. The amount of Cu bound to the organic fraction increased with the application rate, which is probably caused by the formation of organic complexes. For the other metals, the increase of the association with organic matter is very limited. The application of compost moreover increases the amount of Zn associated with Fe and Mn oxides. The “Mobility Factor (MF)” was quite low and did not change after the 5-year application of the two organic amendments. It always remained lower than 10%, although for Cd it amounted to 17%.     

污水厂污泥碱式胶凝稳定化研究

采用氯氧镁稳定剂对污水厂污泥进行了稳定化实验.结果表明,氯氧镁中的MgCl₂具有高吸水性,MgCl₂对每100 g污泥的吸水效率可以达到1.55 mL/g,同时氯氧镁稳定剂在污泥中发生水化反应,还能结合部分水分,可以有效降低污泥的含水率.氯氧镁凝结硬化后的3相和5相为晶体结构,使污泥抗压强度可以达到85.14 kg/cm², 最佳的MOC/污泥=3/100,MgO/MgCl₂=3/1.同时污泥中的Si²⁺、Al³⁺、Cu²⁺等离子在Mg²⁺和OH^-激发下形成了Mg-Si-Al凝胶体系,对污泥中的重金属离子有稳定化作用.浸出实验表明,稳定化污泥中Cu、Zn、Cd、Cr、As 的含量均低于浸出标准值.     

城市污水污泥焚烧处理环境影响分析

以城市污水污泥为研究对象,应用生命周期评价方法分别对干化焚烧、污泥与煤混燃发电、污泥与生活垃圾掺烧发电3种焚烧处理方式的生命过程进行清单分析,以获得各处理方式的能耗及其对环境的影响.结果表明,处理1.0 t湿污泥,填埋处理的能耗和总环境负荷均最低,分别为2.24kg （以标准煤计）和46.55×10-3标准人当量(PET).污泥直接干化处理能源消耗最大,达到了111.12 kg（以标准煤计）.污泥与垃圾或者与煤掺烧发电由于利用固体废弃物化学内能,降低了化石燃料消耗.这两种掺烧处理方式的环境排放都以酸化和富营养化为主,对局地性的影响占据首位,因此,污泥焚烧处理仍需加强尾气净化设备的投入,以减少酸性气体及二噁英的排放.     

两种城市污泥掺混水煤浆的成浆性

研究了两种高含水率城市污泥与煤粉混合研制水煤浆的可行性,以及各种影响因素包括污泥掺混比例、分散剂用量、温度及剪切时间等对成浆性能的影响.结果表明,两种污泥在南京大学研制的亚甲基萘磺钠-苯乙烯磺酸钠-马来酸钠(NDF)分散剂配合下,掺混比例控制在10%以内,可以与煤粉顺利成浆.两种污泥掺混比例分别为5%、10%水煤浆的表观粘度随分散剂的增加而降低,浆体温度的提升有利于改善水煤浆的流动性,添加污泥的水煤浆在稳定性上好于未掺污泥的水煤浆.试验结果可为城市污泥掺制水煤浆的资源化利用途径提供参考依据.     

Effect of proteins, polysaccharides, and particle sizes on sludge dewaterability

Four batch experiments of hydrolysis and acidification were carried out to investigate the distributions of proteins (PN) and polysaccharides (PS) in the sludge, the PN/PS ratio, the particle sizes, and their relationship with sludge dewaterability (as determined by capillary suction time, CST). The sludge flocs were stratified through centrifugation- and ultrasound-based method into four fractions: (1) slime, (2) loosely bound extracellular polymeric substances (LB-EPS), (3) tightly bound EPS (TB-EPS), and (4) pellet. The results showed that PN was mainly partitioned in the pellet (80.7%) and TB-EPS (9.6%) fractions, while PS distributed evenly in the four fractions. During hydrolysis and acidification, PN was transferred from the pellet and TB-EPS fractions to the slime fraction, but PS had no significant transfer trends. The mean particle sizes of the sludge flocs decreased with hydrolysis and acidification. The pH had a more significant influence on the dewaterability of sludge flocs than temperature. Sludge dewaterability during hydrolysis and acidification processes greatly deteriorated from 9.7 s at raw sludge to 340–450 s under alkaline conditions. However, it was just slightly increased under acidic conditions. Further investigation suggested that CST was a ected by soluble PN, soluble PN/PS, and particle sizes of sludge flocs, but was a ected slightly by total PN, PS, or PN/PS in the whole sludge flocs and other fractions (except slime).     

Distribution and elimination of polycyclic musks in three sewage treatment plants of Beijing, China

The two representative polycyclic musks, 1-(5,6,7,8-tetrahydro-3,5,5,6,8,8-hexamethyl-2-naphthenyl)-ethanone (AHTN) and 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[g]-2-benzopyrane (HHCB), were measured in aqueous samples and sludge samples of three sewage treatment plants (STPs) in Beijing, China using a gas chromatograph-mass spectrometry. The HHCB and AHTN concentration ranges in the influents were 1251.4-3003.8 ng/L and 111.9-286.3 ng/L, respectively. Meanwhile, the ranges of 492.8-1285.3 ng/...     

Emission characteristics of dioxins, furans and polycyclic aromatic hydrocarbons during fluidized-bed combustion of sewage sludge

Pre-dried sewage sludge with high sulfur content was combusted in an electrically heated lab-scale fluidized-bed incinerator. The emission characteristics of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polycyclic aromatic hydrocarbons (PAHs) were studied. Coal and calcium oxide (CaO) were added during the sewage sludge combustion tests to optimize combustion conditions and control SO2 emission. The results indicated that the flue gases emitted during mono-combustion of sewage sludge were characterized by relatively high concentrations of SO2, NOx and organic pollutants, due to the high sulfur, nitrogen, and volatile matter content of sewage sludge. The total 16 USEPA priority PAHs and 2,3,7,8-substituted PCDD/Fs produced from sewage sludge combustion were found to be 106.14 g/m3 and 8955.93 pg/m3 in the flue gas, respectively. In the case of cocombustion with coal (msludge/mcoal = 1:1), the 16 PAHs and 2,3,7,8-substituted PCDD/Fs concentrations were markedly lower than those found during mono-combustion of sewage sludge. During co-combustion, a suppressant e ect of CaO on PCDD/Fs formation was observed.