Comparison of linear alkylbenzene sulfonates removal in conventional activated sludge systems and membrane bioreactors.

The potential of a membrane bioreactor (MBR) and a conventional activated sludge (CAS) system to remove polar micropollutants was evaluated using linear alkylbenzene sulfonates (LAS) as model components. Removal efficiencies over 97% were achieved in both reactor systems. The appearance of biological breakdown metabolites and the respirometric response of the sludges to LAS addition indicated that LAS removal was due to biodegradation, rather than sorption phenomena. The effect of operational variables, such as hydraulic retention time, LAS composition and hydrophobicity of the membrane used in the MBR, was negligible in the range tested. A stepwise increase in LAS influent concentration resulted in higher residual effluent concentrations but did not change the procentual removal efficiency. Because an increase in LAS and SPC effluent concentration occurred to a larger extent in the CAS than in the MBR under similar operating conditions, MBRs may turn out to be be more robust with respect to biological degradation of micropollutants than CAS.     

Treatment of linear alkylbenzene sulfonate (LAS) wastewater by internal electrolysis--biological contact oxidation process

Surfactant wastewater is usually difficult to treat due to its toxicity and poor biodegradability. A separate physico-chemical or biochemical treatment method achieves a satisfactory effect with difficulty. In this study, treatment of the wastewater collected from a daily chemical plant by the combination processes of Fe/C internal electrolysis and biological contact oxidation was investigated. For the internal electrolysis process, the optimal conditions were: pH = 4-5, Fe/C = (10-15):1, air-water ratio = (10-20):1 and hydraulic retention time (HRT)= 2 h. For the biological contact oxidation process, the optimal conditions were: HRT = 12 h, DO = 4.0-5.0 mg/L. Treated by the above combined processes, the effluent could meet the I-grade criteria specified in Integrated Wastewater Discharge Standard of China (GB 8978-1996). The results provide valuable information for full-scale linear alkylbenzene sulfonate wastewater treatment.     

Anaerobic thermophilic digestion of sewage sludge with a thickened sludge recycle

The process of anaerobic thermophilic digestion of municipal wastewater sludge with a recycled part of thickened digested sludge, was studied in semi-continuous laboratory digesters. This modified recycling process resulted in increased solids retention time (SRT) with the same hydraulic retention time (HRT) as compared with traditional digestion without recycling. Increased SRT without increasing of HRT resulted in the enhancement of volatile substance reduction by up to 68% in the reactor with the recycling process compared with 34% in a control conventional reactor. Biogas production was intensified from 0.3 L/g of influent volatile solids (VS) in the control reactor up to 0.35 L/g VS. In addition, the recycling process improved the dewatering properties of digested sludge.     

新型UBAF处理合成洗涤剂废水中难降解LAS的效能研究

通过在清水区悬挂生物绳软填料的上向流曝气生物滤池处理合成洗涤剂废水的试验,研究了水力负荷、气水比、污染负荷、滤层高度及溶解氧等对LAS处理效能的影响。结果表明:水力负荷、气水比及滤层厚度是新型UBAF处理效能的主要影响因素,进水污染负荷对LAS处理效能的影响不显著。废水LAS浓度与流经的滤层厚度存在很好的指数关系:Ch=C0ekh。新型UBAF的挂膜性能好,启动速度快,对COD、LAS的处理效能有一定提高。在水力负荷1.1 m3/(m2.h),气水比3∶1～4∶1的运行条件下,对典型合成洗涤剂废水中的LAS去除率达80%以上,处理水的LAS指标达到排放标准。     

Removal of polycyclic aromatic hydrocarbons (PAHs) from sewage sludge by anaerobic degradation.

Due to the hydrophobic nature of the polyaromatic hydrocarbons (PAHs) they are mostly bound to the sludge and escape aerobic treatment in a wastewater treatment plant. They therefore proceed directly to the anaerobic post treatment, terminate in the sludge, and can be released to the environment if land spreading is used. PAH degradation in anaerobic methanogenic systems has only recently been shown to occur. In this study we have assessed several factors of anaerobic PAH degradation by evaluating thermodynamic feasibility of degradation, assessing degradation at different temperatures, and investigating the enriched cultures using fluorescent in-situ hybridization (FISH). Thermodynamic calculations indicated that PAH degradation was possible under methanogenic conditions, in the presence of hydrogen utilizing methanogens. Removal of naphthalene and 1-methyl naphthalene depended both on temperature and the initial inoculum. Inocula sourced from contaminated land sites were the most effective. The enrichments were all a mixture of Bacteria, and Archaea, and the Archaea were generally identified as Methanobacteriales, using an order-specific probe. The bacteria were not specifically identified. The results indicate a syntrophic culture, with the bacteria oxidizing the naphthalene, and the Archaea converting the hydrogen produced by oxidation, to methane.     

Anaerobic codigestion of waste activated sludge and OFMSW: the experiences of viareggio and treviso plants (Italy).

The paper presents the results of two full-scale applications of the anaerobic co-digestion process of waste activated sludge together with the organic fraction of municipal solid wastes. The experiences were carried out at Viareggio and Treviso wastewater treatment plants (Italy). In the first plant, 3 tons per day of source sorted OFMSW were co-digested with waste activated sludge, increasing the organic loading rate from 1.0 to 1.2 kgTVS/m3d. This determined a 50% increase in biogas production. At Treviso WWTP, which has been working for 2 years, some 10 tons per day of separately collected OFMSW are treated using a low-energy consumption sorting line, which allows the removal of 99% and 90% of metals and plastics respectively. In these conditions, the biogas yield increased from 3,500 up to 17,500 m3/month. Industrial costs were evaluated less than 50 Euro per ton of organic waste, while the payback time was calculated as two years.     

Anaerobic degradation of palm oil mill effluent (POME)

The biodegradation characteristics of palm oil mill effluent (POME) and the related microbial community were studied in both actual sequential anaerobic ponds in Malaysia and enrichment cultures. The significant degradation of the POME was observed in the second pond, in which the temperature was 35-37 °C. In this pond, biodegradation of major long chain fatty acids (LCFA), such as palmitic acid (C16:0) and oleic acid (C18:1), was also confirmed. The enrichment culture experiment was conducted with different feeding substrates, i.e. POME, C16:0 and C18:1, at 35 °C. Good recovery of methane indicated biodegradation of feeds in the POME and C16:0 enrichments. The methane production rate of the C18:1 enrichment was slower than other substrates and inhibition of methanogenesis was frequently observed. Denaturing gradient gel electrophoresis (DGGE) analyses indicated the existence of LCFA-degrading bacteria, such as the genus Syntrophus and Syntorophomonas, in all enrichment cultures operated at 35 °C. Anaerobic degradation of the POME under mesophilic conditions was stably processed as compared with thermophilic conditions.     

Impact of sewage sludge applications on the biogeochemistry of soils

This report describes an investigation into the bioavailability and fate of trace metals and their subsequent impact on important soil microbiological functions such as nitrification, denitrification and methane oxidation in low and high Cu containing soils in the presence and absence of residual organic matter from sewage sludge additions made 10 years earlier. The soils being studied are part of long term sewage sludge trials and include a low Cu soil (13.3 mg Cu/kg soil, 4.18 LOI %), left un-amended to serve as a control soil, soil amended with a high Cu sewage sludge (278.3 mg Cu/kg soil, 6.52 LOI %) and soil amended with a low Cu sewage sludge (46.3 mg Cu/kg soil, 6.18 LOI %). Soil was also amended with inorganic metal salts (273.4 mg Cu/kg soil, 4.52 LOI %) to further investigate the impact of Cu in the absence of additional organic matter contained in applied sewage sludge. Data from the first two years of a project are presented which has included field-based studies at long term sewage sludge trials based in Watlington, Oxford, UK and laboratory based studies at the Institute of Grassland & Environmental Research, North Wyke, Devon, UK.     

污泥掺烧比例对生活垃圾协同处置的经济影响分析

市政污泥与生活垃圾协同焚烧不仅能够实现污泥减量化、资源化,而且能达成设备共享,是一种具有综合效益的污泥处置方式.针对三类常见的协同处置模式进行对比分析,研究了污泥掺烧比例对焚烧厂污泥综合处置成本的影响.     

污泥堆肥土地利用对土壤环境及高羊茅特性的影响

结合北京市污泥堆肥土地利用现状．研究了污泥堆肥对土壤环境及高羊茅（Festuca arundinace。）的影响。旨在为北京市污泥堆肥用于高羊茅园林生产提供理论依据,促进资源再利用。研究结果表明．施用污泥堆肥增加了高羊茅栽植小区土壤养分含量,特别是土壤中有机质含量增加明显,与空白对照相比增加了43．9％～73．2％,对土壤养分状况具有一定的改良效果;施用污泥堆肥后,高羊茅栽植小区土壤中重金属含量虽有不同程度的增加。但均远低于相关标准限值．且土壤重金属污染综合指数小于土壤安全限值0．7．表明种植小区土壤未受到重金属污染：施用污泥堆肥对高羊茅生长具有一定的促进作用．与空白对照相比．高羊茅总生物量增长率为16．7％～50．0％。综合分析试验结果,确定污泥堆肥用于高羊茅的适宜施用量为2kg／m^2。     

Characterization and degradation process of sludge profiles inside a facultative pond (Patagonia, Argentina)

To investigate the characteristics and degradation process in sludge profile, three sampling sessions were made in three different places inside the primary facultative pond of Puerto Madryn city, which was located in a region with a temperate climate in coastal Patagonia (Argentina). The sludge showed an extremely negative redox potential (between -441 and -282 mV) and elevated water content and organic matter concentration, ranging from 83.3 to 97.1% for porosity and from 22.5 to 64.4% for organic matter. The surface layer at the Outlet station during the summer showed the greatest concentration of pigments, reaching a maximum value of 10.6 mg/g for chlorophyll-a and 40.9 mg/g for phaeophytin, and a fast diminution with sediment depth. The important concentration of pigment in the surface layer, coincident with phytoplankton bloom in the water column, could support the importance of nitrogen removal via uptake and organic sedimentation in the water column. In warm months the degradation rate was clear, as reflected in a decrease in sediment layer, and even part of the clay bottom was captured inside an 8 cm core sample, registering extremely low concentrations of pigments, carbohydrates, proteins and lipids. The season and the degree of treatment have an influence on sludge characteristics and the organic matter degradation process.     

污泥碱解发酵液用于生活污水脱氮 除磷的效果研究

为了减轻水体富营养化程度,提高污水的脱氮除磷效果,并解决污泥减量化和资源化问题,本研究将碱预处理的污泥进行厌氧发酵产酸,并将发酵液作为污水脱氮除磷的外加碳源。研究结果表明：投加污泥发酵液后,出水氨氮浓度为0.3~0.5 mg/L,总磷浓度为0.5 mg/L,与未投加污泥发酵液相比分别降低了1.7~2.3 mg/L和3~4 mg/L。     

城市污水中EDCs的活性污泥法去除特性研究

以4种(壬基酚(4-n-NP),双酚A(BPA),雌二醇(E2)、乙炔基雌二醇(EE2))内分泌干扰物(EDCs)为目标物,针对其在城市污水处理厂工艺流程中的分布与去除进行了研究,并进一步实验研究了其去除机理。所有EDCs在城市污水厂进出水中均被检出,进水中平均浓度分别为E2:64.8 ng/L,EE2:171.5 ng/L,4-n-NP:115.4 ng/L,BPA:920.7ng/L;出水中平均浓度分别为E2:22.8 ng/L,EE2:49.9 ng/L,4-n-NP:50.9 ng/L,BPA:84.3 ng/L。污水中EDCs目标物的去除主要来自于生物处理阶段,其去除机理主要是生物降解,生物降解速率与EDCs种类及污泥类型有关。污泥吸附对EDCs的去除可产生一定的影响。     

Process performance of dry, batch anaerobic digestion of sewage sludge: methanogenic seed mixtures

A dry, batch anaerobic digestion (DBAD) process was tested on two sewage sludge types with different methanogenic seed fractions under laboratory conditions. The aim was to indicate optimal sludge:seed mixing ratios and analyse process performance based on degradation rate and reactor-specific methane production. The attained results were compared with the performance of a liquid-state, laboratory-scale stirred reactor (SR). A mixing ratio of at least 1:1.25 (sludge:seed) yielded processes free from significant inhibitions. Further seeding increments resulted in slightly better performances, but much lower sludge fractions treated in the reactors. Compared with the SR process, the DBAD reactors produced comparable degradation rates albeit in a significantly longer process and with somewhat lower reactor-specific methane production rates. These findings indicate that the DBAD method may provide a viable alternative to liquid-state processes if sludge drying is already applied and reactor volume requirements are of importance.     

Integrated chemical, physical and biological processes modelling of anaerobic digestion of sewage sludge.

The biological kinetic processes for anaerobic digestion (AD) are integrated into a two phase subset of a three phase mixed weak acid/base chemistry kinetic model. The approach of characterising sewage sludge into carbohydrates, lipids and proteins, as is done in the International Water Association (IWA) AD model No 1 (ADM1), requires measurements that are not routinely available on sewage sludges. Instead, the sewage sludge is characterised with the COD, carbon, hydrogen, oxygen and nitrogen (CHON) composition and is formulated in mole units, based on conservation of C, N, O, H and COD. The model is calibrated and validated with data from laboratory mesophilic anaerobic digesters operating from 7 to 20 d sludge age and fed a sewage primary and humus sludge mixture. These digesters yielded COD mass balances between 107-109% and N mass balances between 91-99%, and hence the experimental data is accepted as reasonable. The sewage sludge COD is found to be 32-36% unbiodegradable (depending on the kinetic formulation selected for the hydrolysis process) and to have a C3.5H7O2N0.196 composition. For the selected hydrolysis kinetics of surface mediated reaction (Contois), with a single set of kinetic and stoichiometric constants, for all retention times good correlation is obtained between predicted and measured results for: (i) COD; (ii) free and saline ammonia (FSA); (iii) short chain fatty acids (SCFA); (iv) H2CO3 * alkalinity; (v) pH of the effluent stream; (vi) CO2; and (vii) CH4 gases in the gas stream. The measured composition of primary sludge from two local wastewater treatment plants ranged between C3.38H7O1.91 N0.21 and C3.91H7O2.04N0.16. The predicted composition based on mass balances is therefore within 5% of the average measured composition providing persuasive validation of the model.     

合肥经开区污水处理厂污泥深度处理技术的应用探讨

合肥经开区污水处理厂污泥高干度脱水项目采用浓缩机、隔膜式板框压滤机作为核心脱水设备,通过投加PAM、PAC进行化学调理改性,可将泥饼含水率控制在60％以下.介绍了板框压滤系统的工作原理和运行参数,对板框设备选型与运行成本进行了详细阐述,使用同一来源污泥对三套污泥脱水系统进行了比较,其中板框压滤机生产每吨干泥需投加PAM...     

Improvement of the thickening and dewatering characteristics of activated sludge by electroflotation (EF).

The performances of electroflotation (EF) on the thickening of activated sludge were investigated using laboratory scale batch flotation reactors. Four activated sludges including bulking sludges were tested. After 30 minutes of EF operation, 57-84% of sludge volume reduction could be achieved by EF, while only about 1.5-14% could be obtained by gravity thickening for the same period. After thickening the effluent water quality in terms of TCOD, SS, and turbidity was improved by EF operation for all sludge samples. In addition, the EF thickened sludge showed much better dewaterability both in SRF and cake solid content. It is induced that the air bubbles entrapped in the thickened sludge play a key role in the observed dewaterbility improvement.     

Anaerobic treatment as a core technology for energy, nutrients and water recovery from source-separated domestic waste(water).

Based on results of pilot scale research with source-separated black water (BW) and grey water (GW), a new sanitation concept is proposed. BW and GW are both treated in a UASB (-septic tank) for recovery of CH4 gas. Kitchen waste is added to the anaerobic BW treatment for doubling the biogas production. Post-treatment of the effluent is providing recovery of phosphorus and removal of remaining COD and nitrogen. The total energy saving of the new sanitation concept amounts to 200 MJ/year in comparison with conventional sanitation, moreover 0.14 kg P/p/year and 90 litres of potential reusable water are produced.     

污泥制取脱氮除磷材料的配比试验研究

以微波处理后城市污水厂污泥、天然沸石和水泥为原材料,不进行任何改性,探讨原材料的最佳配比,研制一种既具有脱氮除磷功能,又具备抗压强度,并可在水体中保持一定形态的低能耗环保合成材料.结果表明,水泥∶天然沸石∶污泥的质量比为1∶2∶0.05,水灰比为0.4,发泡剂∶水的体积比为1∶60时,合成材料的耐水性能良好,7d的抗压强度为5.8 MPa,满足用于净化水景、河道底部及驳岸生态混凝土的强度要求,对氮、磷去除效果良好,平衡吸附量分别为50、83.5 mg/kg,符合准二级动力学模型.     

Anaerobic degradation of purified terephthalic acid wastewater using a novel, rapid mass-transfer circulating fluidized bed

The anaerobic treatability of purified terephthalic acid (PTA) wastewater in a novel, rapid mass-transfer fluidized bed reactor using brick particles as porous carrier materials was investigated. The reactor operation was stable after a short 34 day start-up period, with chemical oxygen demand (COD) removal efficiency between 65 and 75%, terephthalate (TA) removal efficiency between 60% and 70%, and system organic loading rate (OLR) increasing from 7.37 to 18.52 kg COD/m(3) d. The results demonstrate that the reactor is very efficient, and requires a low hydraulic retention time (HRT) of 8 h to remove both TA and COD from the high-concentration PTA wastewater. The system also has high resistance capacity to varied OLR.