Orbal氧化沟同时硝化/反硝化及生物除磷的机理研究

对６个采用分段,闭环沟道的Ｏｒｂａｌ氧化沟工艺运行数据进行了分析评定,以确定在该工艺中同时发生生物脱氮除磷的程度,较低的总氮出水浓度表明,同时硝化／反硝化在Ｏｒｂａｌ工艺中很易发生。由于泥龄较长并保持外沟道低溶解氧,有利于硝化菌的生长并提高脱氮效率;由于每个沟道处于相对均匀混合的状态,因此沟道内没有明显的好氧或缺氧段之分,表明产生反硝化的必要的缺氧环境可能发生在菌胶团内部。     

生物/化学组合工艺处理高盐榨菜废水的除磷效能

针对高盐度废水生物除磷的难点问题,采用生物/化学组合工艺处理高盐度、高磷、高氮的榨菜腌制废水,考察了运行工况、挂膜密度、排泥周期、药剂种类和投加量等对除磷效能的影响.试验结果表明:采用厌氧/生物除磷/生物脱氮/化学除磷组合工艺除磷高效、可行,当一级SBBR生物除磷单元的挂膜密度为60%、排泥周期为2 d、运行工况为进水(O.2 h)-厌氧(3 h)-好氧(6 h)-沉淀及排水(0.2 h),化学除磷单元按物质的量之比为9:1投加硫酸铝时,在进水COD及(PO3-4)-P分别为10 000 mg/L和38.5 mg/L的条件下,出水COD和(PO3-4)-P分别为90和0.1mg/L,去除率均达到了99%以上.生物除磷、生物脱氮、化学除磷单元的除磷分担率分别为56.6%、20.8%和22%.     

Enhanced nutrient removal by biological treatment systems

The importance of nitrogen and phosphorus in stimulating eutrophic conditions in receiving waters has been well documented. As a result, over the last decade an increased emphasis has been placed on limiting these elements in wastewater effluents. In the future, new discharge permits will include limits on both of these elements.

In 1985 a research program was initiated to conduct a pilot plant study of an anoxic/anaerobic/aerobic treatment train using primary effluent. The facility was operated at varying flow and Qr/Q ratios, and at effective mixed liquor suspended solids (MLSS) concentrations of 3100 mg/L. The results of the first 13 month operational phase indicated that the effluent concentrations of total BOD₅, TSS and nitrate nitrogen were less than 5 mg/L. Ammonia nitrogen was less than 0.2 mg/L. The solids settleability was excellent, and foaming due to Norcadia, was effectively controlled. The average overall phosphorus removal was 48%. Influent BOD₅ concentrations of less than 100 mg/L significantly reduced the system's ability to remove phosphorus. A strong relationship between the amount of carbon source in the influent, phosphorus release in the anoxic and anaerobic tanks and phosphorus uptake in the aeration basin was established.     

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.     

Biological Nutrient Removal: Design Snags, Operational Problems and Costs

The EC urban waste water treatment Directive will lead to some sewage-treatment works in the UK having to remove nitrogen and phosphorus. The paper reviews the basic biological processes which are available for retrofitting existing activated-sludge plants to achieve this removal, and then points to some of the problems which are encountered with these processes in other countries. The authors make suggestions as to how these problems can be overcome in design and operation. The paper also provides a cost comparison of different ways of uprating an existing nitrifying activated-sludge plant to achieve nitrification/ denitrification and phosphorus removal.     

Nitrogen and phosphorus removal from municipal wastewater effluent using microalgal biofilms

Microalgal biofilms have so far received little attention as post-treatment for municipal wastewater treatment plants, with the result that the removal capacity of microalgal biofilms in post-treatment systems is unknown. This study investigates the capacity of microalgal biofilms as a post-treatment step for the effluent of municipal wastewater treatment plants. Microalgal biofilms were grown in flow cells with different nutrient loads under continuous lighting of 230 μmol/m²/s (PAR photons, 400-700 nm). It was found that the maximum uptake capacity of the microalgal biofilm was reached at loading rates of 1.0 g/m²/day nitrogen and 0.13 g/m²/day phosphorus. These maximum uptake capacities were the highest loads at which the target effluent values of 2.2 mg/L nitrogen and 0.15 mg/L phosphorus were still achieved. Microalgal biomass analysis revealed an increasing nitrogen and phosphorus content with increasing loading rates until the maximum uptake capacities. The internal nitrogen to phosphorus ratio decreased from 23:1 to 11:1 when increasing the loading rate. This combination of findings demonstrates that microalgal biofilms can be used for removing both nitrogen and phosphorus from municipal wastewater effluent.     

The thickening and treatment of sewage sludges to minimize phosphorus release

The Johannesburg City Council has operated biological and chemical nutrient removal wastewater treatment plants for the past 15–16 years. With the advent of more sophisticated sludge handling techniques, problems have been experienced with the recycle of phosphorus-rich sludge processing liquors to the liquid phase. These problems are expected to increase in the future. This paper describes laboratory and pilot scale experiments to determine viable methods for phosphorus removal from sludge liquors and ways of obviating phosphorus release from phosphorus-rich activated sludges. The design of new full-scale plants being constructed to pretreat phosphorus-rich sludges prior to dewatering are also discussed. The paper also describes innovative process layouts for sludge treatment keeping in mind various options for final sludge disposal. Emphasis is placed on the pre-aeration and phosphate precipitation from anaerobically digested and raw primary sludges and techniques for the thickening and dewatering of primary and waste activated sludges to minimize phosphate release into the liquors so produced. The technique of sludge thickening on linear screens is described and the coupling of linear screens to belt presses to complete the dewatering operation.     

Enhanced uptake of phosphorus by activated sludge-effect of substrate addition

Studies were undertaken to examine the effect of substrate addition upon the release and subsequent uptake of phosphorous by a biological wastewater treatment laboratory scale system.A train of six reactors were fed at a rate of 16 ml min⁻¹ raw wastewater using a sludge recycle ratio of 0.75 (12 ml min⁻¹). The first two reactors were simply stirred (anoxic) without the addition of air and the remaining four were aerated with excess air.Various substrates were added to the first reactor (anoxic) at different concentrations. It was determined that all the short chain substrates tested enhanced the release of phosphorus in the anoxic stages and subsequently led to increased biological uptake (removal) of phosphorus. The substrates tested included sodium acetate, acetic acid, butyric acid, ethanol and methanol.It was determined that 30 mg l⁻¹ sodium acetate was the optimum dose for biological release and uptake of phosphorus and the addition of any greater concentration had marginal effect on the ultimate removal of phosphorus.The effect of these substrates showed some specificity regarding phosphorus release, with butyric acid causing the greatest release and sodium acetate the least. However as far as phosphorus uptake (removal) was concerned, this phenomenon of substrate-specificity was less significant. For all substrates, effluent phosphorus concentration was within ± 1 mg l⁻¹ with an approximate mean concentration of 1 mg l⁻¹ residual.Phosphorus released (approx. 14 mg l⁻¹) at higher temperature (29°C) was 75% greater than at the lower temperature (24°C). Similarly the final residual phosphorus at 29°C was 33% lower than at 24°C.     

污水处理过程中除磷加药智能控制系统及应用研究

应用基于化学除磷模型和在线传感器的智能控制系统对污水处理厂的药剂投加量进行优化控制,以达到污水处理厂一级A总磷排放标准。以广州市某污水处理厂为例,设计了除磷加药智能控制系统的控制策略,拟合出化学除磷公式,以表征智能除磷系统的应用效果。结果表明,在一般城市生活污水的总磷浓度条件下,可以节约除磷药剂量40%~50%,2~3年便可回收控制系统的建设成本。污水处理厂采用该除磷加药智能控制系统后,可以实现在出水水质稳定达标的前提下降低加药量的目标。     

序批式一体化膜生物反应器的脱氮除磷效果

采用序批式一体化膜生物反应器(SBSMBR)处理模拟生活污水,考察了其脱氮除磷效果.该工艺通过合理控制单个反应器的曝气时间和曝气量来构建交替式厌氧/好氧环境,试验中反应器内混合液的污泥沉降性能始终保持良好,平板膜没有进行化学清洗,未产生不可逆的膜污染;不同工况下系统对COD、氨氮、总氮和总磷的平均去除率分别达到96.39%、97.79%、89.30%和43.79%,且系统的抗冲击负荷能力强.     

Elimination of enteric bacteria in biological-chemical wastewater treatment and tertiary filtration units

The occurrence and removal of salmonellae and faecal indicators in four conventional municipal wastewater treatment plants (MWTP) were investigated. In addition, we tested the efficiency of a semi-technical scale biological nutrient removal process and three pilot-scale tertiary filtration units in microbial removal. All influent samples collected from MWTPs contained salmonellae from 93 to 11,000 MPN/100 ml and indicator bacteria from about 10(7) to 10(8) CFU/100 ml. The reductions in salmonella numbers achieved in full-scale biological-chemical wastewater treatment and semi-technical scale biological nutrient removal processes were usually between 94% and virtually 100% (99.9%) and indicator bacteria reductions between 2 and 3 log units. Microbial numbers in MWTP effluents could be modelled as a function of effluent residual organic matter, suspended solids and total phosphorus concentrations. Pilot-scale tertiary treatment by rapid sand contact filter, chemical contact filter and biological-chemical contact filter reduced salmonella numbers below the detection limit and faecal coliform numbers on average by 99%, 39% and 71%, respectively. A total of 32 Salmonella serovars were identified among 197 Salmonella isolates from municipal wastewaters. Of the isolates, 32% were resistant to nalidixic acid, indicating reduced sensitivity to ciprofloxacin, the drug of choice in the treatment of salmonellosis. In addition, 18% of the isolates were multiresistant. Our results, especially antibiotic resistant Salmonella strains, indicate that conventional municipal wastewater treatment without efficient tertiary treatment, like filtration or disinfection, may constitute a risk for public health.     

Behaviour of pharmaceutical products and biodegradation intermediates in horizontal subsurface flow constructed wetland. A microcosm experiment

Horizontal subsurface flow constructed wetlands (SSFCWs) are a cost-effective and sustainable alternative to conventional wastewater treatment plants (WWTPs) for sanitation in small communities. SSFCWs are designed to remove suspended solids and organic matter from wastewater but there is little information on the effect of the characteristics of organic matter on the removal efficiency of specific contaminants. In this paper, carbamazepine, ibuprofen and clofibric acid were continuously injected into two SSFCW microcosms fed with synthetic wastewater containing different organic matter sources: dissolved (glucose) and particulate (starch). The response curves of carbamazepine and ibuprofen were compared with that of clofibric acid, which was used as a conservative tracer. The removal efficiencies were found to be independent of the organic matter type (i.e. dissolved or particulate). Carbamazepine was removed inefficiently (5%) by bed sorption, whereas ibuprofen was removed by degradation (51%). In addition, the behaviour of the two main ibuprofen biodegradation intermediates (carboxy and hydroxy derivatives) supported that the main ibuprofen elimination pathway occurs in aerobic conditions.     

城市污水同步生物脱氮除磷工艺特点及选择

分析了多种较为成熟的城市污水同步生物脱氮除磷工艺的特点,指出了选择生物脱氮除磷工艺时应考虑的因素,为污水处理厂脱氮除磷工艺选择与设计提供参考。     

Treatment of domestic wastewater using the nutrient film technique (NFT) to produce horticultural roses

Removal of organic matter, nitrogen and phosphorus was investigated in a pilot based on the nutrient film technique system used for horticultural production. Rosebushes producing commercial roses were set on an inclined impermeable surface over which a thin film of domestic wastewater flowed directly through the root matrix. The roses produced with wastewater as nutrient solution were qualitatively and quantitatively similar to those produced traditionally and can be marketable. In the presence of the rosebushes, the lowering of chemical oxygen demand (COD), biological oxygen demand (BOD5) and suspended solids (SS) increased with their influent strengths in a linear fashion correlation. Whatever the pollutant load of the influent, within the range studied, the level of organic pollution required to allow the discharge of the effluent into water courses was reached after 24 h of treatment. At this time, the COD reached 39 +/- 13 mg L(-1), the BOD5 7 +/- 4 mg L(-1) and the SS 8 +/- 6 mg L(-1). The removal percentages were 89, 95 and 94, respectively, whereas without plants they were 55, 33 and 53, respectively. The rosebushes had a beneficial effect on the removal of phosphorus from 20% to 23% greater in their presence than without. In presence of plants, the nitrate was the principal form of nitrogen from 48 h of treatment whereas without rosebushes, nitrite represent more than 20% of initial nitrogen whatever the treatment duration. The root matrix served not only as a filter for the organic matter, but also provided a microhabitat suitable for nitrifying bacteria and heterotrophic micro-organisms, which responded rapidly to the pollutant load.     

Nutrient Removal: Experiences in Johannesburg (Abridged)

The ability to remove nitrogen and phosphorus by biological means in the activated-sludge process represents the most significant refinement of the process since its discovery. This paper reviews the development of the activated-sludge process in Johannesburg. Emphasis is placed on the last twenty years'research into biological nutrient removal and the successful incorporation of research findings into the design and operation of full-scale plants of up to 200 Ml/d capacity.     

FeSO_4应用于SBBF强化除磷

序批式生物膜滤池(SBBF)是基于序批式生物膜法的改进污水处理新型工艺,针对SBBF处理城市污水的除磷的效果较差的弊端,通过直接投加FeSO_47H_2O到反应体系实现协同除磷,使得该工艺能够较好地应用于污水脱氮除磷。Fe(Ⅱ)的投加量从0.03~0.3mM进行协同除磷试验,结果表明0.2mM的Fe(Ⅱ)投加可为有效投加量。进一步将0.2mM的Fe(Ⅱ)在进水阶段后投加到反应体系,稳定运行1个月,发现出水的TP稳定保持在0.5mg/L以下,而COD和氮的去除基本不受影响。COD、NH_4~+-N、TN和TP的平均去除率分别为84.9%、83.2%、46.3%和88.2%。反应器出水的各项指标均稳定达到《城镇污水处理厂污染物排放标准》(GB 18918—2002)的一级A排放标准。     

MBR工艺在无锡三座城市污水厂中的应用分析

膜生物反应器(MBR)是一种新型高效的污水处理技术,在城市污水处理与回用及升级改造中具有良好的应用前景。从工程概况、运行效果及技术经济指标入手,对无锡三座采用MBR工艺的城市污水厂(硕放污水厂、梅村污水厂及新城污水厂)进行了分析比较。结果表明,各污水厂出水水质基本能实现稳定排放并达到GB 18918—2002的一级A标准;增加后置缺氧段的硕放污水厂脱氮除磷效果优于其他两座污水厂;各污水厂能耗为0.6～0.7 kW.h/m3,膜化学清洗药剂消耗费用约5 000元/月;因进水碳源不足,视天气及冲击负荷影响,各污水厂均不定期投加醋酸,以保证出水水质达标。根据三座污水厂的运行情况,指出膜组件和生物段的合理布置及优化,是未来城市污水MBR工艺处理的研究方向。     

Phosphate recovery using hybrid anion exchange: Applications to source-separated urine and combined wastewater streams

There is increasing interest in recovering phosphorus (P) from various wastewater streams for beneficial use as fertilizer and to minimize environmental impacts of excess P on receiving waters. One such example is P recovery from human urine, which has a high concentration of phosphate (200–800 mg P/L) and accounts for a small volume (∼1%) of total wastewater flow. Accordingly, the goal of this study was to evaluate the potential to recover P from source-separated and combined wastewater streams that included undiluted human urine, urine diluted with tap water, greywater, mixture of urine and greywater, anaerobic digester supernatant, and secondary wastewater effluent. A hybrid anion exchange (HAIX) resin containing hydrous ferric oxide was used to recover P because of its selectivity for phosphate and the option to precipitate P minerals in the waste regeneration solution. The P recovery potential was fresh urine > hydrolyzed urine > greywater > biological wastewater effluent > anaerobic digester supernatant. The maximum loading of P on HAIX resin was fresh urine > hydrolyzed urine > anaerobic digester supernatant ≈ greywater > biological wastewater effluent. Results indicated that the sorption capacity of HAIX resin for phosphate and the total P recovery potential were greater for source-separated urine than the combined wastewater streams of secondary wastewater effluent and anaerobic digester supernatant. Dilution of urine with tap water decreased the phosphate loading on HAIX resin. The results of this work advance the current understanding of nutrient recovery from complex wastewater streams by sorption processes.     

白龙港污水厂出水达到一级A的优化运行中试研究

倒置A2/O工艺已广泛应用于新建城镇污水处理厂和老厂脱氮除磷工艺的改造,但在实际运行中常因进水碳源不足和工艺控制不合理,致使出水磷含量无法达到一级A标准.在白龙港污水厂进行中试,研究了混合液回流比、曝气量、进水分流对倒置A2/O工艺除磷效果的影响.试验结果表明,对碳源含量偏低的进水,在保证出水氮浓度达标的前提下适当降低混合液回流比和曝气量,并采用进水分流措施可有效提高除磷效果,出水水质可满足一级A标准的要求.     

SBR法处理低碳城市污水的除磷规律

碳、氮、磷比例失调(碳量偏低)城市污水的脱氮除磷一直是个难题,为此采用SBR法处理广州地区低碳城市污水,研究了生物除磷效果及其影响因素。结果表明,磷的出水浓度<0.5mg/L,并指出污泥龄及DO是影响除磷效果的关键因素。