Incorporation of inorganic material in anoxic/aerobic-activated sludge system mixed liquor

In the bioreactor of the nitrification denitrification (ND)-activated sludge system, the mixed liquor is made up of organic and inorganic materials. In the current design procedures and simulation models, the influent wastewater characteristics and biological processes that influence the bioreactor mixed liquor organic solids (as volatile suspended solids, VSS, or COD) are explicitly included. However, the mixed liquor total suspended solids (TSS, i.e. organic+inorganic solids) are calculated simply from empirical ratios of VSS/TSS. The TSS concentration is fundamental in the design of secondary settling tanks and waste activated sludge disposal. Clearly, the empirical approach to obtaining an estimate for TSS is not satisfactory within the framework of a fundamentally based model. Accordingly, the incorporation of the inorganic material present in the influent wastewater into ND-activated sludge system mixed liquor was investigated. From an experimental investigation into the distribution of inorganics in the influent, mixed liquor and effluent of a laboratory-scale ND-activated sludge system, it was concluded inter alia that (i) of the total inorganic solids in the influent, only a small fraction (2.8–7.5%) is incorporated into the mixed liquor, (ii) most of the inorganics in the influent (mean 88%) and effluent (mean 98.5%) are in the dissolved form, the balance being particulate, and (iii) the influent and effluent inorganic dissolved solids concentrations are closely equal (mean effluent to influent ratio 100%). Further, a number of models were developed to quantify the mixed liquor inorganic, and, hence, total solids. From an evaluation of these models against the experimental data, it would appear that the best approach to model the incorporation of inorganics into the activated sludge mixed liquor is to follow the concepts and principles used to develop the existing models for organic materials. With this approach, reasonably close correlation between predicted and measured data for mixed liquor and effluent inorganic concentrations were obtained.     

The microbiology of an activated sludge waste-water treatment plant chemically treated for phosphorus removal

Microbiological research was conducted on a dual, secondary wastewater treatment system which was part of The Pennsylvania State University wastewater treatment plant. Each aeration basin received identical wastewater which was the effluent from a high rate trickling filter. One of the aeration basins was dosed with aluminum sulfate for the purpose of phosphorus removal. The other aeration basin (control) was operated in the conventional manner without alum addition. Plate counts performed on combined chemical-biological sludge and control activated sludge revealed that a higher number of viable micro-organisms was contained in the chemical-biological sludge, but the magnitude of difference between the two sludges was significant depending on the culture medium employed. Results suggest the aluminum flocs formed in the chemical-biological treatment enmesh dispersed wastewater micro-organisms, some of which are qualitatively unlike those indigenous to natural activated sludge. The combined chemical-biological sludge contained significantly higher numbers of lipolytic, gelatinolytic, and thiosulfate oxidizing micro-organisms and, possibly, fewer nitrite oxidizing micro-organisms than did control activated sludge. Alum did not appear to affect flagellated protozoa in mixed liquor; however, amoeboid and ciliated protozoa were found less frequently in alum dosed than in control mixed liquor. The settled effluent from the combined chemical-biological aeration basin generally contained fewer total coliforms, fecal coliforms, and fecal streptococci than did counterpart control effluents.     

Removal of native coliphages and coliform bacteria from municipal wastewater by various wastewater treatment processes: implications to water reuse

The efficacy of a conventional activated sludge wastewater treatment process and the membrane bioreactor technology in removing microbial pathogens was investigated. Total and fecal coliforms and somatic and F-specific coliphages were used as indicators of pathogenic bacteria and viruses. Up to 5.7 logs removal of coliforms and 5.5 logs of coliphages were observed in the conventional treatment process with advanced tertiary treatment. Addition of chemical coagulants seemed to improve the efficacy of primary and secondary treatment for microorganism removal. Complete removal of fecal coliforms and up to 5.8 logs removal of coliphages was observed in the MBR system. It was shown that the MBR system was capable of high removal of coliphages despite the variation in feed coliphage concentrations. The results of this study indicated that the MBR system can achieve better microbial removal in far fewer steps than the conventional activated sludge process with advanced tertiary treatment. The final effluent from either treatment processes can be potentially reused.     

Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in sewage treatment plants

In this study, the concentrations of PFOS and PFOA in the biological units of various full-scale municipal sewage treatment plants were measured. Samples of influent, primary effluent, aeration tank effluent, final effluent and grab samples of primary, activated, secondary and anaerobically digested sludge were collected by 5 sampling events over one year. The two sewage treatment plants (STPs) selected for this study include plant A receiving 95% domestic wastewater and plant B receiving 60% industrial wastewater and 40% domestic wastewater. PFOS and PFOA were observed at higher concentration in aqueous and sludge samples in plant B than that of plant A. Mass flow of PFOS increased significantly (mean 94.6%) in conventional activated sludge process (CAS) of plant B, while it remained consistent after the secondary treatment in plant A. Mass flow of PFOA increased 41.6% (mean) in CAS of plants A and B and 76.6% in membrane biological reactor (MBR), while it remained unchanged after the treatment of liquid treatment module (LTM). Our results suggest that mass flow of these two compounds remains consistent after treatment of activated sludge process operating at short sludge retention time (SRT). Seasonal variations of PFOS in concentrations of raw sewage were found in plant A, while PFOA did not have significant seasonal variation in both plants A and B.     

水产品加工废水处理工程

采用接触氧化法处理水产品加工废水 .经过 2年运行 ,结果表明 :进水水质 COD<1 2 0 0 mg相似文献   

多段活性污泥法处理高浓度中药废水

采用多段活性污泥法处理高浓度中药废水。运行结果表明，尽管进水有机物浓度很高，但该工艺运行稳定，对COD和BOD，的去除率均超过99％，出水水质达到《污水综合排放标准》（GB8978-1996）的一级标准。     

Release of infectious human enteric viruses by full-scale wastewater utilities

In the United States, infectious human enteric viruses are introduced daily into the environment through the discharge of treated water and the digested sludge (biosolids). In this study, a total of 30 wastewater and 6 biosolids samples were analyzed over five months (May-September 2008-2009) from five full-scale wastewater treatment plants (WWTPs) in Michigan using real-time PCR and cell culture assays. Samples were collected from four different locations at each WWTP (influent, pre-disinfection, post-disinfection and biosolids) using the 1MDS electropositive cartridge filter. Adenovirus (HAdV), enterovirus (EV) and norovirus genogroup II (NoV GGII) were detected in 100%, 67% and 10%, respectively of the wastewater samples using real-time PCR. Cytopathic effect (CPE) was present in 100% of the cell culture samples for influent, pre- and post-disinfection and biosolids with an average log concentration of 4.1 (2.9-4.7, range) 1.1 (0.0-2.3, range) and 0.5 (0.0-1.6, range) MPN/100 L and 2.1 (0.5-4.1) viruses/g, respectively. A significant log reduction in infectious viruses throughout the wastewater treatment process was observed at an average 4.2 (1.9-5.0, range) log units. A significant difference (p-value <0.05) was observed using real-time PCR data for HAdV but not for EV (p-value >0.05) removal in MBR as compared to conventional treatment. MBR treatment was able to achieve an additional 2 and 0.5 log reduction of HAdV and EV, respectively. This study has demonstrated the release of infectious enteric viruses in the final effluent and biosolids of wastewater treatment into the environment.     

Biotransformation of arsenic species by activated sludge and removal of bio-oxidised arsenate from wastewater by coagulation with ferric chloride

The potential of activated sludge to catalyse bio-oxidation of arsenite [As(III)] to arsenate [As(V)] and bio-reduction of As(V) to As(III) was investigated. In batch experiments (pH 7, 25 degrees C) using activated sludge taken from a treatment plant receiving municipal wastewater non-contaminated with As, As(III) and As(V) were rapidly biotransformed to As(V) under aerobic condition and As(III) under anaerobic one without acclimatisation, respectively. Sub-culture of the activated sludge using a minimal liquid medium containing 100mg As(III)/L and no organic carbon source showed that aerobic arsenic-resistant bacteria were present in the activated sludge and one of the isolated bacteria was able to chemoautotrophically oxidise As(III) to As(V). Analysis of arsenic species in a full-scale oxidation ditch plant receiving As-contaminated wastewater revealed that both As(III) and As(V) were present in the influent, As(III) was almost completely oxidised to As(V) after supply of oxygen by the aerator in the oxidation ditch, As(V) oxidised was reduced to As(III) in the anaerobic zone in the ditch and in the return sludge pipe, and As(V) was the dominant species in the effluent. Furthermore, co-precipitation of As(V) bio-oxidised by activated sludge in the plant with ferric hydroxide was assessed by jar tests. It was shown that the addition of ferric chloride to mixed liquor as well as effluent achieved high removal efficiencies (>95%) of As and could decrease the residual total As concentrations in the supernatant from about 200 microg/L to less than 5 microg/L. It was concluded that a treatment process combining bio-oxidation with activated sludge and coagulation with ferric chloride could be applied as an alternative technology to treat As-contaminated wastewater.     

常德市垃圾渗滤液处理厂SBR工艺雪灾后的端动

常德市垃圾渗滤液处理厂为实现SBR工艺的快速启动,采用接种城市污水厂污泥的方法,先对污泥进行强制驯化,然后进行工艺调试。结果表明,当进水量为50m3/d时,出水COD为400mg/L左右,氨氮<10mg/L。     

啤酒污泥用作城市污水厂种泥的试验研究

为考察啤酒厂污水处理站的脱水污泥（简称啤酒污泥）用作城市污水厂接种污泥的可行性，摸索污泥的培养与驯化规律，采用连续操作、全流量同步培养和驯化方法，在处理能力为500m^2／d的UNITANK池中对啤酒污泥进行了培养和驯化。试验结果表明，啤酒污泥完全可以作为城市污水处理厂的接种污泥使用，而且培养时间短，出水水质好。曝气0．5h、厌氧搅拌1h时，活性污泥增长最快。将DO控制在2mg／L左右有利于活性污泥的增长；当DO长时间在7mg／L以上时，污泥浓度下降趋势明显。污泥浓度达到2000mg／L所需的培养驯化时间仅为5d；使出水水质达到一级B标准所需的培养时间约为6d。这种培养、驯化方法和经验可为其他城市污水处理厂的建设和运行提供参考。     

The influence of nitrilotriacetic acid on heavy metal transfer in the activated sludge process—II. At varying and shock loadings

In laboratory simulations of the activated sludge process, the impact of shock loads of the detergent builders sodium tripolyphosphate (STPP) and nitrilotriacetic acid (NTA) on the transfer of heavy metals to the effluent, has been studied. Experiments have also been undertaken in which the influent concentration of each builder was doubled, in an endeavour to simulate the effect of a “wash day”. It is apparent from the data presented that NTA, when present under either of these conditions, resulted not only in deterioration of metal removal by the activated sludge process but caused a mobilisation of heavy metals from the sludge. Copper and lead were the metals most extensively affected. The mobilisation of heavy metals from the mixed liquor to the effluent in activated sludge units acclimated to NTA, upon a doubling of the influent NTA concentration, resulted from a failure by the activated sludge unit to completely degrade the additional NTA. The concentration of NTA in the effluent rose to 4.7 mg l⁻¹ following the increase in influent concentration. Ten days were required before effluent NTA concentrations returned to values equivalent to those prior to the increase in influent concentration. When condensed phosphates were added as shock load or upon the doubling of their influent concentration only the removal of copper was adversely affected.     

Coliphage prevalence in high school septic effluent and associated ground water

At the present time, somatic and male-specific coliphage and human enterovirus groups are being considered as indicators of possible pathogenic human enteric virus contamination from fecal contamination. A primary attribute for any indicator of fecal contamination is its prevalence at the source and in associated ground water. It must be consistently found in the source material at concentrations that are measurable with available techniques. Over a period of ten months, male-specific and somatic coliphage ranged from 7000 to 4,000,000 PFU/L in the effluent from a multi-user septic-tank. Unlike the values determined for septic-tank effluent, coliphage concentrations measured in ground water over this same period only varied by five-fold. Coliphage concentration in ground water under the down-gradient edge of the drainfield contained 1000 PFU/L. This concentration decreased at −1 log₁₀/5 m during 17.4 m of ground-water transport. From these data, coliphage concentrations in septic-tank effluent seem sufficient to allow their use as indicators of fecal contamination in ground water.     

生化法处理港口化学品洗舱废水试验研究

港口有机散化洗舱废水采用活性污泥法处理工艺，易产生丝状菌污泥膨胀。经理论分析及历时８个多月的试验研究，证明采用串级生物接触氧化法处理港口有机散化洗舱废水，稳定有效。进水ＣＯＤ平均浓度３０００ｍｇ／Ｌ，停留时间２４ｈ，ＣＯＤ有机负荷率４．３０ｋｇ／（ｍ３·ｄ），出水ＣＯＤ浓度小于１５０ｍｇ／Ｌ，可回用于洗舱，从而为散化洗舱废水处理开创了一条新路。     

ASM2d在污水处理中的研究与应用

介绍了描述脱氮除磷动态过程的活性污泥数学模型No．2d（ASM2d）的内容及应用ASM2d进行污水处理分析的模拟过程，并应用基于ASM2d开发的模拟程序ASM2G对某污水厂进行了模拟分析，通过参数校正，最后得到的二沉池出水模拟结果与实测结果符合较好（误差〈10％），说明ASM2d能较好地反映污水处理的实际运行状况，可用于模拟污水处理、预测出水水质及作辅助工艺设计的平台。     

Viruses and bacteriophages

Many of the enteric viruses which are transmitted from person to person by thefecal-oral route are found in raw and treated wastewater, and because of their persistence under adverse conditions may also be found in slightly polluted waters.There is no routine examination procedure of water and wastewater for entero-viruses,mainly because of the cumbersome isolation techniques, high cost and the need for highly skilled laboratory personnel.Phages are specific to single species of bacteria, are known for many entericbacteria, and are very often used for final identification of enteric pathogenic bacteria.Coliphages are provalent in raw and treated sewage as well as in polluted water, where enteric viruses may also be found.Coliphages were often mentioned as possible viral indicators in polluted water.To be a perfect indicator, they should comply with minimum criteria as follows: (a) they should be present wherever human enteric viruses are present: (b) the coliphage numbers recovered should be equal to or larger than those of enteric viruses recovered: (c) the coliphages should be at least as resistant as enteric viruses to adverse environmental conditions: (d) isolation and quantification of the coliphage should be faster and less expensive than isolation of the enteroviruses.Comparative studies show that the coliphage to enterovirus ratio in wastewater is about 10³:1. Levels of poliovirus 1 (attenuated) to coliphage f2 remained stable for a few months in oxidation pond effluents.f2 coliphage exhibited higher resistance to chlorination than poliovirus 1 (attenuated). When the two strains were kept in water of different quality, f2 survived longer. In addition, all coliphage counts were completed within 24 h. while those of enteroviruses required about a week. Results indicate very strongly that coliphages can be used as viral indicators and this is already the practice in a few European and other countries.     

Activated sludge response to emulsified lipid loading

The possible adverse effects of natural fats and oils (lipids) upon biological wastewater treatment systems have been the subject of much speculation and some disagreement. This study addressed the specific question of possible effects of emulsified lipids upon activated sludge process performance. Lipid form and fatty acid composition were determined on wastewater samples. Experimental studies employing bench scale activated sludge units indicated that effluent quality is either not significantly different or occasionally is better than that from sucrose supplemented control plants receiving comparable organic loading (F/M > 0.80). Furthermore, emulsified lipids clearly do not exhibit an inhibitory effect on either the specific soluble substrate utilization rate or the mixed liquor oxygen consumption rate.However, effluent quality parameters were found to be dependent upon unit lipid loading to a highly significant degree. As well, unit lipid loading (g lipid g⁻¹ MLSS-day) provided a better explanation of effluent quality than either the food to microorganism ratio or the mixed liquor lipid burden (g lipid extracted from MLSS g⁻¹ MLSS). The findings of this study indicate the conditions where lipid overloading occurs. This data provides a basis for controlling emulsified lipid loading to the activated sludge process which should apply to plants which receive high lipid loading such as those encountered in industrial wastewater treatment applications.     

Enterovirus and coliphage inactivation during activated sludge treatment

The inactivation rates of poliovirus 1, coxsackievirus B-1 and wastewater indigenous coliphages were determined during activated sludge treatment in a large volume reactor. Virus and phage inactivation closely approximated first order kinetics and the inactivation rates were independent of mixed liquor flow rates. The inactivation rates for the enterovirus and coliphages were not significantly different, suggesting that phage inactivation could be used as an indicator for enterovirus inactivation during activated sludge treatment. Total virus removal from mixed liquor and virus inactivation were determined, and a method is presented predicting the fate of viruses during activated sludge treatment.     

The effect of primary sedimentation on full-scale WWTP nutrient removal performance

Traditionally, the performance of full-scale wastewater treatment plants (WWTPs) is measured based on influent and/or effluent and waste sludge flows and concentrations. Full-scale WWTP data typically have a high variance which often contains (large) measurement errors. A good process engineering evaluation of the WWTP performance is therefore difficult. This also makes it usually difficult to evaluate effect of process changes in a plant or compare plants to each other. In this paper we used a case study of a full-scale nutrient removing WWTP. The plant normally uses presettled wastewater, as a means to increase the nutrient removal the plant was operated for a period by-passing raw wastewater (27% of the influent flow). The effect of raw wastewater addition has been evaluated by different approaches: (i) influent characteristics, (ii) design retrofit, (iii) effluent quality, (iv) removal efficiencies, (v) activated sludge characteristics, (vi) microbial activity tests and FISH analysis and, (vii) performance assessment based on mass balance evaluation. This paper demonstrates that mass balance evaluation approach helps the WWTP engineers to distinguish and quantify between different strategies, where others could not. In the studied case, by-passing raw wastewater (27% of the influent flow) directly to the biological reactor did not improve the effluent quality and the nutrient removal efficiency of the WWTP. The increase of the influent C/N and C/P ratios was associated to particulate compounds with low COD/VSS ratio and a high non-biodegradable COD fraction.     

Virus removal during simulated soil-aquifer treatment

Removals of indigenous coliphage and seeded poliovirus type 1 during simulated soil-aquifer treatment were evaluated during transport of secondary effluent under unsaturated flow conditions in 1-m soil columns. Independent variables included soil type (river sand or sandy loam) and infiltration rate. Removal of coliphage was in all cases less than removal of poliovirus type 1 (strain LSc-2ab), supporting contentions that indigenous coliphage can act as a conservative indicator of groundwater contamination by viral pathogens of human origin. Coliphage retention was significantly more efficient (p<0.001) in the finer-grained sandy loam (93%) than in sand (76%). Increasing reactor detention time from 5 to 20 h increased coliphage attenuation from 70% to 99% in a 1-m sand column. There was a significant linear correlation (p=0.012) between log-transformed (fractional) coliphage concentration [log(C/C(0))] and reactor detention time. Re-mobilization of attached coliphage occurred during simulated rainfall using low-ionic-strength water. Inhibition of aerobic respiration resulted in significantly less efficient coliphage attenuation (p=0.033), suggesting the involvement of aerobic microorganisms in the survival/retention of this virus.