Operational Optimisation of Pilot Scale Biological Nutrient Removal at the Ciudad Real (Spain) Domestic Wastewater Treatment Plant

The aim of this work is optimising operating conditions for a possibleimplementation of a Biological Nutrient Removal (BNR) process in the Wastewater Treatment Plant (WWTP) of Ciudad Real (Spain). Several factors (hydraulic retention times, anaerobic nitrate concentration, sludge age and wastewater biodegradability) were tested using a pilot scale VIP (Virginia Initiative Plant) activated sludge process and domestic wastewater from the full scale plant. Hydraulic retention times used did not cause changes in N and P removal. P removal was adversely affected by anaerobic NO₃ ^- and improved with higher BOD₅/COD ratios in wastewater. Influence of sludge age was very low in P removal, but N removal was mainly affected by this factor. Final operating conditions were selected taking into account their effects over one of both nutrients. COD and SS removal were always successful. N removal was also easily reached and the main difficulty was P removal. P sludge content was very low (2.5–4%) approximately and was also affected by the same factors tested. The main factor to improve P removal was supposed to be the organic wastewater composition. Wastewater characteristics were modified by using different sources from the WWTP. Volatile fatty acids (VFA) addition to the wastewater by using supernatant of the anaerobic sludge digesters seemed to be the best practical solution for a future BNR implementation in the WWTP.     

污水处理反硝化除磷-诱导结晶磷回收工艺中除磷微生物特性

为探究反硝化除磷-诱导结晶磷回收工艺中缺氧池污泥释磷、吸磷以及微生物特征,利用荧光原位杂交(fluorescence in situ hybridization,FISH)技术、电子扫描显微镜(scanning electron microscope,SEM)观察了微生物的数量、分布和形态;通过批次试验考察了污泥在厌氧/好氧和厌氧/缺氧2种模式下的释磷和吸磷特征。结果表明:该双污泥系统缺氧池中聚磷菌占总细菌比例的69.7%,明显高于单污泥系统中富集的聚磷菌比例,污泥中的微生物多呈杆状;厌氧/好氧、厌氧/缺氧模式下单位污泥浓度(mixed liquor suspended solids,MLSS)总吸磷量(以PO43--P计)分别为22.84、18.60 mg/g,反硝化聚磷菌(denitrifying polyphosphate-accumulating organisms,DPAO)占聚磷菌(polyphosphate-accumulating organisms,PAO)的比例为81.44%,表明在长期的厌氧/缺氧运行条件下可以富集到以硝酸盐为电子受体的反硝化聚磷菌,同时还存在着仅以氧气为电子受体的聚磷菌;通过pH值和氧化还原电位(oxidation reduction potential,ORP)的实时监测可以快速地了解污水生物处理系统中各类反应的进程,对调控工艺参数有着重要的意义。综上所述,为保证污水生物处理工艺的正常稳定运行,将微生物分析与常规的化学参数分析结合起来考察将是未来发展的必然趋势。     

Application of Adsorption and Ultrafiltration Processes for the Pre-treatment of Several Industrial Wastewater Streams

In this work ultrafiltration (UF) was coupled with suitable minerals and dried activated sludge for the pre-treatment of several industrial wastewater streams. The aim was to decrease heavy metal concentrations to low levels so that wastewater can be safely discharged into municipal sewers or biological wastewater treatment can take place without biomass inhibition problems. Industrial wastewater originating from metal plating, chemical and textile industries was employed. The experiments were conducted in a reactor where the UF membrane module was immersed. UF reduced the amount of heavy metals, but the performance was variable with removal efficiencies ranging from 20 to 99.7?%, depending on the metal type and on the wastewater initial characteristics. The prevailing wastewater characteristics were the pH, the presence of certain anions, the suspended solids concentration and the presence of competing cations. The addition of activated sludge and/or minerals could further increase heavy metal removal through the process of sorption. UF assisted by minerals could achieve variable colour and COD removal ranging from 22 to 94?% and 58 to > 99.9?% respectively. Minerals resulted in membrane fouling mitigation, while sludge adversely impacted on fouling.     

Mercury pathways in municipal wastewater treatment plants

A nine-week sampling and analysis program was completed at a large municipal wastewater treatment plant to characterize the fate of Hg entering the plant. Mercury removal in primary treatment averaged 79%, and the average Hg removal across the entire plant was approximately 96%. Mercury loadings on the secondary (activated sludge) treatment process were elevated to near plant influent levels due to the recycle of spent scrubber water from sewage sludge incinerator emissions control equipment. This internal recycle of spent incinerator scrubber water resulted in elevated Hg loadings to the incinerators, and effectively reduced the Hg control efficiency of the emissions control equipment to near zero. Measurements indicate that approximately 95% of the Hg mass entering the plant is discharged to the atmosphere via sludge incinerator emissions. These results indicate that municipal wastewater treatment facilities can remove Hg from wastewater quite effectively; however, where wastewater sludge is incinerated, almost the entire mass of Hg removed from the wastewater can be discharged to the atmosphere.     

Chemical and Ecotoxicological Assessment of Selected Biologically Activated Sorbents for Treating Wastewater Polluted with Petroleum Products with Special Emphasis on Polycyclic Aromatic Hydrocarbons

A chemical and ecotoxicological assessment of treatment of wastewater that had been polluted with petroleum products using only Activated Sludge (AS) and four biologically activated sorbents (BASs), consisting of activated sludge plus: coal-based activated carbon (-C1), coconut shell-based activated carbon (-C2), zeolite (-Z), and anthracite (-A) were conducted. The efficiency and robustness of the four wastewater treatment systems were evaluated by calculating the reduced total petroleum hydrocarbon (TPH) and polycyclic aromatic hydrocarbon (PAH) contents and the acute ecotoxicity of the effluents. The chemical analysis showed that the combined treatment systems were very effective for reducing the total petroleum hydrocarbon and readily bioavailable PAH contents. The most efficient systems were the BAS-C1 and -C2, which removed 60–88% and 99.5–99.6% of TPH and PAH, respectively. The activated sludge-only treatment was the least effective for purifying the wastewater. Chemical oxygen demand was reduced by >90% by all carbon-based BASs (BAS-C1, BAS-C2 and BAS-A). Shifts in the relative composition of the individual PAHs were identified in samples taken before and after treatment. Algal and bacterial bioassays showed that the toxicities of effluents following treatment by all four systems (except AS for algae) were reduced by more than 80% and 90%, respectively. However, crustacean tests indicated that the carbon-based BASs reduced the toxicity [V _tox(50)] only by 19–67%. Our results indicated that the combination of sorption and biodegradation processes have great potential in the treatment of petroleum products polluted wastewater and is less sensitive for inhibitors of the biological process than treatments in which activated sludge alone is used. The assessment of chemical and ecotoxicological endpoints provided valuable information, but contrasting results for one of the assays indicates that further analysis on the capacity of the different treatment systems is warranted.     

Effects of Nitrolotriacetic Acid-Copper Complexes on Activated Sludge Process

Effects of nitrilotriacetic acid (NTA), copper ion (Cu2+) and their complexes on the efficiency of activated sludge process were evaluated by determining the changes in physical and chemical parameters in a laboratory-scale unit. Primary effects of these toxicants on microorganisms in the activated sludge process were also evaluated by determining the change of in vivo dehydrogenase activity. The presence of 1 mg L-1 or higher of Cu2+ significantly affected the activated sludge process. Nitrification in the activated sludge process was more sensitive to the inhibition of Cu2+. The presence of NTA, as high as 20 mg L-1, did not significantly affect the activated sludge process. Moreover, in the presence of 20 mg L-1 of NTA, the toxicity of Cu2+ on the activated sludge process was significantly reduced.     

Sequential solar photo-fenton-biological system for the treatment of winery wastewaters

In this study, winery wastewaters are considered for degradation using heterogeneous photo-Fenton as a preliminary step before biotreatment. The heterogeneous photo-Fenton process assisted by solar light is able to partially degrade the organic matter present in winery wastewaters. When an initial hydrogen peroxide concentration of 0.1 M is used over 24 h of treatment, a degradation yield of organic matter (measured as TOC) of around 50% is reached. The later treatment (activated sludge process) allows the elimination of 90% of the initial TOC present in pretreated winery wastewaters without producing nondesired side-effects, such as the bulking phenomenon, which is usually detected when this treatment is used alone. The final effluent contains a concentration of organic matter (measured as COD) of 128 mg O2/L. The coupled system comprising the heterogeneous photo-Fenton process and biological treatment based on activated sludge in simple stage is a real alternative for the treatment of winery wastewater.     

废水污泥生物炭对圣女果生长、产量及重金属累积效应的对比评估

To investigate the potential effects of wastewater sludge and sludge biochar on growth, yield and metal bioaccumulation of cherry tomato ({\it Lycopersicon esculentum} L.), a pot experiment was carried out under greenhouse environment with three different treatments, control soil (CP), soil with wastewater sludge (SS) and soil with sludge biochar (SB), to reveal the comparative effect between the amendments of wastewater sludge and sludge biochar.~The soil used for pot experiment was Chromosol.~Wastewater sludge and sludge biochar produced through pyrolysis process at 550 $^\circ$C were applied at 10 t ha$^{-1}$. No significant difference was found in growth and production of cherry tomatoes between wastewater sludge and sludge biochar applications to the soil. The accumulation rates of metals in the fruits were lower in the treatment with sludge biochar than in the treatment with wastewater sludge. The study highlights the benefits of risk mitigation from toxic metal accumulation in fruits using wastewater sludge and sludge biochar as soil conditioners.     

Biological treatment of pharmaceutical wastewater

A study of physicochemical and biological treatment of pharmaceutical wastewater by the activated sludge process was performed in an oxidation ditch. The physicochemical study using different coagulants revealed that all the coagulants used are not effective and their doses required were very high for COD reduction. In the biological oxidation study, it was found that the wastewater could be processed at all organic loadings and phenol concentrations encountered in wastewater. The yield coefficient and decay coefficient were 0.75 (COD basis) and 0.01 day^?1 (COD basis), respectively.     

Aerobic biodegradation of precoagulated cheese whey wastewater

Prior to the application of an aerobic biological process, cheese whey wastewater has been pretreated by means of a precipitation stage by adding either NaOH or CaOH2. Both precipitating agents reduce roughly 50% of the raw wastewater chemical oxygen demand (COD). The sludge generated in the prestage shows acceptable settling properties, although solids from the CaOH2-treated effluent are better separated from the liquid bulk than those formed in NaOH-processed wastewater. In both situations, the presedimentation stage renders a supernatant more prone to biodegradation than the untreated effluent. The previous statement is corroborated by the determination of some biological kinetic parameters. Under the operating conditions used in this work, sludge generation after the biological process is reduced to a minimum. The sludge generated shows good settling properties, especially for those experiments in which CaOH2 has previously been added.     

葡萄酒生产废弃物与剩余污泥厌氧共消化研究进展

厌氧消化技术被广泛应用于多种行业废弃物的处置。然而,葡萄酒生产废弃物浓度高、pH值低以及季节性变化的特性容易造成负荷冲击,导致反应器微生物流失、运行不稳定。同时,剩余污泥组分复杂、水解率低导致产气效率低。厌氧共消化具有均衡营养素、减缓抑制效应、丰富菌群多样性和提高甲烷产量等优势,也逐渐成为一种重要的葡萄酒生产废弃物与剩余污泥的处置方式。尽管已有二者在不同运行策略下共消化性能的研究,但仍未有报道阐明其共消化的影响因素以及基于葡萄酒生产废弃物特性建立直接种间电子传递的研究进展。因此,该文介绍了葡萄酒生产废水与剩余污泥、葡萄酒生产固体废弃物与剩余污泥的共消化进展,并分别归纳了2种体系中影响消化效能的主要因子;随后总结了共消化体系中基于乙醇建立的直接种间电子传递的研究进展;最后,围绕以上内容展望了共消化技术在葡萄酒生产废弃物与剩余污泥协同处理的前景。     

Physicochemical requirements in the environment of the earthworm Eisenia foetida

Survival and/or growth were used to assess optimum and potentially deleterious physico-chemical conditions in the environment of the earthworm Eisenia foetida. Maximum weight was gained between 20 and 29°C with horse manure or activated sludge as food. Maximum weight gain as a function of moisture in activated sludge occurred between 70 and 85%. All worms died within a week at pH values <5 or >9; optimum pH for gain in weight centered around 7.0 Soluble salts in excess of 0.5% were lethal, though ammonium acetate caused 100% mortality at a concentration of 0.1%; concentrations in manures contaminated by urine or cattle slurry may be lethal, while those present in noncontaminated manure, with an electrolytic conductivity of 1.5–3mmhos, support weight gain. Inorganic chemicals that are commonly used to coagulate sludges, often as a preliminary to land application, were innocuous at concentrations higher than those normally used at wastewater treatment plants. Anaerobically digested sludges are toxic to earthworms, and are characterized by low oxidation-reduction potentials; when placed upon a soil substrate the redox potential increases slowly, and though the sludge tested in this study was nontoxic at Eh values in excess of 250 mV, it provided insufficient nutriment to E. foetida to allow weight gain. With activated sludge as food, growth of E. foetida occurred more rapidly when soil was present, independently of whether it was placed as a substrate beneath the sludge or mixed into the sludge. Growth occurred more rapidly when activated sludge was placed on substrates which allowed drainage, though loam or ashed loam appeared superior to others, such as glass beads or sand; the growth promoting factor is related to the inorganic fraction of the soil.     

Na+和K+共存对A2/O工艺脱氮除磷效果及污泥性质的影响

为了揭示多种金属离子共存的含盐废水生物处理系统污染物的去除机制和污泥特性,考察Na~+、K~+共存对A~2/O工艺污染物去除率、污泥性质和微生物群落的影响,采用高通量测序技术分析了厌氧区、缺氧区和好氧区的微生物群落结构,结合脱氮除磷效果和污泥性质的变化,探讨不同Na~+/K~+摩尔比下A~2/O工艺优势种群的演替规律,以期从微生物角度明确Na~+、K~+共存对含盐废水污染物去除率的影响。结果表明:当进水Na~+/K~+摩尔比分别为2、1和0.5时,A~2/O工艺的COD去除率分别为80%、84%和86%,TN去除率分别为73%、77%和80%,K~+浓度的提高缓解了Na~+对COD和TN去除率的抑制作用;厌氧区释磷率分别为70%、73%和74%,缺氧区吸磷率分别为53%、55%和58%,好氧区吸磷率分别为70%、72%和75%。随着进水Na~+/K~+摩尔比的降低,厌氧区、缺氧区和好氧区微生物群落的丰富度和多样性降低,微生物群落差异显著,变形菌门的相对丰度均升高约30%,拟杆菌门和绿弯菌门相对丰度逐渐降低。陶氏菌属和固氮弧菌属作为优势菌属,其相对丰度逐渐增大,有利于氮磷污染物的去除。通过增加K~+的浓度有利于提高氮、磷去除率,增强污泥的生物絮凝性和反硝化聚磷菌的活性。     

Hydraulic Retention Time Influence on Improving Flocculation in the Activated Sludge Processes Through Polyelectrolytes

Hydraulic retention time (HRT) influence improving sludge flocculation with adding the polyelectrolytes (non-ionic, anionic, and cationic) was studied on an activated sludge (AS) system fed with synthetic domestic wastewater (SDW), dairy industry wastewater (DIW), and caramel industry wastewater (CIW). The sludge volumetric index, food/microorganism ratio (F/M), and mixed liquor volatile suspended solids at different HRTs (6, 8 and 10 h) were monitored on an experimental model. Results showed that both SDW and IW had the best sludge flocculation conditions at 8 h and 100 mL of non-ionic polyelectrolyte (0.2 mg L^?1). In addition, this phenomenon reached the organic matter removal efficiencies of 95.9, 95.7, and 94.2% for SDW, DIW, and CIW, respectively. Therefore, optimum HRT increased the organic matter removal efficiencies by 10%, sludge concentration by 37% (22–55%), and F/M ratio by 70%. Moreover, the polyelectrolytes used in AS improved the sludge flocculation by 2.9 times.     

Distribution of Metal Extractable Fractions during Anaerobic Sludge Treatment in Southern Spain WWTPs

A new European Union legislation on sludge treatment isbeing introduced that will replace the one currently in force.The control of heavy metals is an important aspect of this newlegislation. The most common methodology to examine the metalcontent of sludges is determination of total metal contentafter total or pseudo total digestion of the sludge samples.Nevertheless, this kind of analysis is not informative on theavailability or mobility of the metals; a metal speciationanalysis is therefore required. In this study, sludge samplesfrom conventional activated sludge wastewater treatment plants(WWTP) were collected at different stages of an anaerobicsludge treatment process. In these samples, the total metalcontent and the distribution of metal species were determined(Al, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Ti, Zn) followinga protocol of sequential extraction. Only 14% of the metalwas present in readily available forms in the treated sludges.In composted sludges, this value dropped to 6%.     

Fe3+和Na+共存对缺氧污泥脱氮除磷效率和胞内外聚合物的影响

为了提高多种金属离子共存的含盐废水脱氮除磷效率和生物絮凝性,考察Fe^3+和Na^+共存对A2O工艺缺氧区污染物去除率的影响,研究缺氧区胞内聚合物(Intracellular Polymeric Substances,IPS)和胞外聚合物(Extracellular Polymeric Substances,EPS)的变化,采用气相色谱法与蒽酮比色法分析IPS中聚-β-羟丁酸(Poly-β-hydroxybutyrate,PHB)和糖原含量的变化,结合三维荧光光谱(Three-dimensional Excitation Emission Matrix Fluorescence Spectroscopy,3D-EEM)与傅里叶变换红外光谱(Fourier Transform Infrared Spectroscopy,FTIR)探索EPS组成结构的变化,以期揭示共存的Fe^3+和Na^+、IPS及EPS与污泥絮凝性的关系。结果表明:1)单一Fe^3+的加入有助于提高COD、TN和TP的去除率,增加碱性磷酸酶与酸性磷酸酶活性,IPS和EPS总量增多。2)在Fe^3+和Na^+共存的条件下,当Fe^3+浓度为10 mg/L、Na^+浓度为0.5 g/L时,低浓度的Na^+提高了COD、TN和TP去除率,增强了碱性磷酸酶与酸性磷酸酶活性,增加了IPS总量,但是抑制了微生物EPS的分泌,EPS总量下降;当Fe^3+为10 mg/L,Na^+浓度(>1 g/L)继续升高时,高浓度的Na^+导致COD、TN和TP去除率下降,IPS总量降低,但是促进了微生物EPS的分泌,EPS总量增加。3)由FTIR分析可知,Fe^3+和Na^+浓度的变化并未导致松散结合型胞外聚合物(Loosely Bound Extracellular Polymeric Substances,LB-EPS)和紧密结合型胞外聚合物(Tightly Bound Extracellular Polymeric Substances,TB-EPS)的官能团发生明显变化,主要成分始终为蛋白质(Protein,PN)和多糖(Polysaccharide,PS);由3D-EEM分析可知,Fe^3+的加入使三维荧光光谱中出现了可见区类色氨酸峰,Na^+的加入使色氨酸、腐殖酸类物质降解,EPS的成分改变。4)IPS和EPS之间存在竞争生长,IPS/EPS比值较高时,IPS占主导作用,污泥絮凝性能好。     

Optimal design of single and multiple stage activated sludge processes

The present paper describes a rational approach to minimum cost design of an integrated activated sludge process which includes activated sludge reactor, secondary clarifier and sludge recycle. The cost of anaerobic digestion of excess sludge produced is also considered. Procedures for optimal design of both single and multiple stage activated sludge processes, considering construction and operational costs are developed. Biomass concentration in aeration tank and return sludge are utilized as the primary independent design variables to which system performance is related for single stage process. In the multiple stage process, additional design variables (flow and volume fractions for each stage) are included in design vector. Liquid-biomass separation is based on the batch solids flux theory. The optimization problem is framed as minimization of capital and operating cost subject to the constraints determined by effluent quality criteria and process variables affecting the performance. The interior penalty function method is used. Results definitely favor the application of multiple stage process over single stage. The major factor which appears to be contributing to reduction in cost is the biological solids retention time and hence the aeration tank volume.     

Anarwia工艺处理猪场废水节能效果的研究

分析比较了厌氧-加原水-间隙曝气(Anarwia)工艺、SBR(序批式反应器)以及厌氧-SBR工艺处理猪场废水的效果。比较三种工艺处理效果表明：厌氧-SBR工艺处理猪场废水，污染物去除效率低，出水污染物浓度高，不适于猪场废水的处理。Anarwia工艺处理效果与SBR工艺相当，污染物去除率高，出水COD和NH₃-N浓度低。在此基础上，以一个日处理1200 t猪场废水处理工程为例，分析比较了Anarwia与SBR工艺的能耗。就能量消耗有关的工艺参数——污泥量和需氧量而言，Anarwia工艺分别比SBR工艺减少16.4%和95.9%，此外Anarwia工艺每天可产生2784 m³沼气。Anarwia工艺增加了废水提升能耗，但减少了曝气、污泥处理、滗水和搅拌的能耗，结果Anarwia工艺总电耗比SBR工艺低81.0%。Anarwia工艺产生的沼气用于发电能完全补偿消耗的能量，并有剩余。     

Treatment of Domestic Wastewater by Enhanced Primary Decantation and Subsequent Naturally Ventilated Trickling Filtration

To treat household wastewater, a sequence of ‘primary decantation–trickling filter percolation’ was applied in a lab-scale designed treatment system. Poly-electrolyte was used as coagulant to enhance the primary treatment and charcoal was used as carrier material in the trickling filters. Oxygen was supplied to the trickling filters by means of natural ventilation. In the lab-scale system, the enhanced primary stage removed more than 91% of the suspended solids (SS), and 79% of the total chemical oxygen demand (CODt). The subsequent trickling filtration brought a complete nitrification to the wastewaters at a volumetric loading rate (Bv) of 0.7–1.0 g CODt L^-1 d^-1. On average, the concentrations of the CODt and SS in the final effluents were about 55 and 15 mg L^-1 respectively. With respect to phosphate, physico-chemical removal was the dominant process. About 46–62% of total P was removed from the tested wastewaters. The integrated treatment system also achieved a fair degree of hygienisation. The numbers of total coliforms, fecal coliforms and fecal streptococci were decreased by 2–4 log units. The sludge production of the entire treatment system was about 1.7% (v/v) of the treated wastewater. Only primary sludge was produced; secondary sludge produced in the trickling filters was negligible. The cost savings in terms of minimization of sludge production and aeration energy are estimated to be substantial (i.e. some 50%) relative to a conventional activated sludge system.     

Anammox反应器的启动及其菌群演变的研究

为了研究工艺条件对反应器内微生物多样性的影响,该论文采用城市污水处理厂活性污泥接种,通过培育硝化污泥,进行了启动厌氧氨氧化(Anammox)反应器的试验,并对启动过程中细菌的多样性变化作了跟踪研究。研究结果表明,以好氧活性污泥作为接种物,可成功地培育硝化生物膜;通过反应器运行条件的控制,硝化生物膜可从进行好氧氨氧化反应过渡到进行厌氧氨氧化反应。在此过程中,异养型细菌的数量大幅度下降,硝化细菌、反硝化细菌和厌氧氨氧化细菌的数量增大,推测它们都与厌氧氨氧化作用有关。运用PCR-DGGE技术证明,随着反应器运行时间的延长,菌群发生明显变化并呈现简化趋势。