强化低碳源污水生物除磷的技术方式探究

以一营养物去除工艺——BNR为研究对象,分别采用试验与模拟,研究了通过厌氧上清液侧流磷回收和外加碳源方式对低碳源污水生物除磷的强化作用。试验结果与模拟预测双双显示,对COD/P值=50的实际生活污水实施30%的厌氧上清液旁路磷沉淀可明显强化生物除磷作用,使出水TP浓度从碳源抑制时的1.8 mgP/L下降至0.5 mgP/L以下。侧流磷回收不仅可回收40%的进水磷负荷,亦可节省27%的外加碳源。因此,厌氧上清液侧流磷回收与外加碳源对强化生物除磷作用有着异曲同工之处。模拟预测与试验结果几乎一致的演示表明,数学模拟技术可取代传统试验进行相关问题研究。     

磷回收提高生物除磷效果的验证

在前期的模拟试验中曾预测，磷回收介入生物营养去除（BNR）工艺，不仅有利于提高生物除磷效果，而且可以降低生物除磷所需的进水COD／P值。为了证实这一预测，以传统A^2／O工艺作为主要流程进行试验。结果表明，当侧流比达到20％时，满足排放标准（TP〈1mg／L）的最低COD／P值从原来的35降低到25，此时对磷的有效回收率为34％。这意味着，在生物除磷过程中可节约25％～30％的碳源。     

倒置A2/O工艺硝化除磷调控的实例分析

北京清河污水处理厂一期工程采用倒置A^2／O工艺，运行2年以来，在保证出水NH3-N达标的情况下仅通过生物除磷就使出水TP≤0．3mg／L。实践证明，在工艺调控中掌握一些关键控制点，使倒置A^2／O工艺的硝化除磷能力充分发挥，是高效生物除磷的关键。     

序批式生物膜法除磷机理研究

利用^31P-核磁共振谱图证实了生物除磷的机理，即除磷菌在厌氧条件下分解胞内的聚磷酸盐并释放出正磷酸盐形式的无机磷酸盐，而在好氧或缺氧条件下吸收胞外的无机磷酸盐后转化为聚磷酸盐而贮存于胞内。同时证明了淹没序批式生物膜反应器中磷的去除是由生物完成的。     

Variations in the morphological phosphorus in a full-scale A2O + MBR process with heavy chemical P removal addition dosing

The removal of biological phosphorus (P) removal along with chemical P removal additions is significantly important role in removing P at full-scale wastewater treatment plants (WWTPs). Few research groups have recently reported the use of P forms in these WWTPs. The current study mainly presents the varied forms of morphological phosphorus and the fate of chemical P removal agents in a full-scale WWTP that has adopted the A²O + MBR process. With time, the TP concentration in the liquid phase and the solid phase reaches the minimum (0.27 mg/L) and maximum values (1.75 mg/g), respectively. At this point, the TP concentration at the end of the aerobic and membrane pool becomes nearly constant. This indicates the complete removal of effluent TP from in the system. The heavy chemical P removal and addition dosing result in Al–P being the predominant P form in the solid phase. The fate of the chemical P removal and agents was determined by investigating the valences of the surface elements in freeze-dried MLSS at the membrane pool.     

短好氧泥龄下A2/O和BAF联合工艺的脱氮除磷特性

采用小试装置,研究了短好氧污泥龄下A2/O和BAF联合工艺处理低C/N和C/P污水时的脱氮除磷特性.结果表明,通过提高A2/O工艺段的厌氧区有机负荷和缺氧区硝酸盐负荷对反硝化聚磷菌（DPAOs）进行选择和强化后,其在聚磷菌（PAOs）中的比例维持在28%左右,工艺具有部分反硝化除磷能力,能够减少脱氮除磷过程中对碳源的总需求量.但在联合工艺中,好氧除磷仍是主要的除磷方式.在A2/O工艺段内,好氧污泥龄在满足好氧PAOs存活的同时,还必须满足抑制硝化细菌生长的要求,且为了保证工艺对磷的整体去除效果,混合液在好氧区的接触时间须大于30 min.此外,以保证缺氧区出水中含有1～4 mg/L的硝态氮为原则来控制BAF出水的回流量,可达到较好的脱氮除磷效果.该联合工艺结合了活性污泥工艺和生物膜工艺的优点,运行稳定,出水水质优良,不仅适合于新建污水处理厂,也特别适合于不能脱氮除磷污水处理厂的技术改造.     

Phosphorus removal in the activated sludge process

The results from this research suggest that both calcium phosphate precipitation and enhanced biological uptake play a role in phosphorus removal in the activated sludge process when a non-nitrifying, anaerobic-aerobic system is used to treat a low calcium wastewater. The primary removal mechanism was found to be biological uptake, as calcium phosphate precipitation accounted for only 15–27% of the total phosphorus removed. Calcium phosphate precipitation in the aerobic unit was enhanced because of the pH increase in that reactor. This was the result of low CO₂ production (indicated by low specific oxygen uptake values) and intense aeration which caused excessive CO₂ stripping in the aerobic unit     

MBR组合工艺脱氮除磷研究进展

常规MBR工艺处理城市生活污水尽管可以获得较低SS的出水,但对氮、磷的去除却很难达到愈来愈严格的排放要求,因此强化MBR工艺生物段的脱氮除磷功能成为目前研究的热点问题。分析了MBR脱氮除磷的潜力,介绍了各种MBR组合工艺脱氮除磷的原理、特点及处理效果,探讨了MBR组合工艺脱氮除磷的研究方向,认为微生物学机理、强化内源反硝化及膜污染控制等是其研究重点。     

SBR工艺对低碳量城市污水的反硝化除磷研究

广州地区的城市污水含碳量低，碳、氮、磷浓度比例失调，采用传统工艺处理很难达到理想的脱氮除磷效果，为此采用SBR工艺对其进行处理，考察了该工艺的反硝化除磷效果。结果表明，在厌氧／缺氧／好氧的运行模式下，采用逐步增加缺氧段运行时间的方法可有效提高污泥的反硝化除磷性能；在试验进水水质条件下，反应器厌氧运行30min、缺氧运行3h、好氧运行1h可保证对磷的稳定高效去除，出水TP〈1mg／L；ORP值无法指示缺氧反硝化与吸磷过程，pH值可作为缺氧吸磷结束的指示参数，而ORP和pH值均可作为好氧吸磷结束的控制参数。     

化学混凝对两级曝气生物滤池出水的除磷效果研究

为解决两级曝气生物滤池处理城市污水时除磷效果欠佳的问题，采用化学混凝工艺对其出水进行处理，以聚合硫酸铁（PFS）为絮凝剂，通过烧杯试验考察了PFS投量及助凝剂聚丙烯酰胺（PAM）对除磷效果的影响，并通过中试考察了混凝、沉淀、过滤工艺的除磷效果。结果表明，PAM的助凝作用并不明显，单独投加130mg／L的PFS即可使出水TP〈1mg／L。在生物处理单元稳定运行的情况下，中试工艺的PFS投量在90-95mg／L时可使出水TP〈1mg／L，总铁〈0．5mg／L。     

Experimental and model assisted investigation of an operational strategy for the BPR under low influent concentrations

The behaviour of a pilot scale biological phosphorus removal process (BPR) of the alternating type was investigated during periods of low influent concentrations and increased hydraulic load. A process disturbance of this type result in an increase in the phosphate concentration level in the anoxic/aerobic reactors and in the plant effluent shortly after the influent wastewater returns to normal strength. The accumulation of phosphorus in the system was avoided by the addition of an external carbon source either to the influent or to the effluent from the anaerobic reactor in form of sodium acetate. With the help of such an addition, the internal carbon storage compounds could be maintained at a high level, which is shown by poly-hydroxy-alcanoates (PHA) measurements. Several levels of acetate addition were investigated experimentally in order to determine a minimal amount of internally stored carbon, which could ensure the stabilization of BPR during such dynamic influent conditions. Furthermore reduction of aeration time during periods of low influent concentrations was investigated. It was observed that BPR was stabilized by combining a reduction of aeration time with carbon source addition, which maintained the internal stored carbon at a higher level. This combined control action resulted in a desired high BPR activity when the normal strength of the influent wastewater was re-established. The failure of the BPR process was sometimes observed even when comparatively high concentrations of PHA could be detected and an identification of a minimal PHA level was not possible. During this investigation an extended version of the activated sludge model No. 2 (ASM2), which includes denitrification by phosphate accumulating organisms, is used for the detailed analysis of the experiments. The model predicted the phosphorus build-up after the process disturbance as well as the performance during the stabilized experiments. Assisted by the model, the investigations indicate that a PHA limitation is not the only factor affecting the recovery of the BPR process during periods of low influent concentrations.     

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.     

Effect of exogenous carbon sources on removal of inorganic nutrient by the nitrification-denitrification process

A bench scale study was undertaken to examine the effects of exogenous carbon substrates on the removal of inorganic nitrogen and phosphorus by a simple nitrification-denitrification process. Each plastic tank reactor was subjected to a 7-h aeration followed by a 5-h anoxic stage. Methanol, glucose and sodium acetate, at the concentrations equivalent to theoretical COD values of 100 and 200 mg O₂ l⁻¹ were used as external carbon sources and were added to the reactors prior to the anoxic stage. Effects of these additions on biological phosphate release were also investigated. The results showed that 94% of NH₄⁺-N was removed at the end of the aeration period. During the anoxic stage, reduction of nitrate to nitrogen gas was recorded and the denitrification process was significantly enhanced by the addition of organic carbon substrates. At the end of the anoxic stage, over 90% reduction was achieved in the tanks with exogenous carbon substrates while only 47% of NO₃⁻-N was removed in the control reactors. Among the three substrates, sodium acetate was the most efficient and effective source, followed by methanol and glucose. Addition of sodium acetate not only increased the amount of nitrate reduction but also enhanced the rate of N removal especially when a high dosage of sodium acetate was used. With respect to phosphorus removal, 88% ortho-P was removed after the aerobic stage. Throughout the anoxic stage, P concentration was maintained at about 2 mg l⁻¹ in both control and methanol treated reactors. However, significant increase in effluent P content was recorded in both sodium acetate and glucose treatments indicating that phosphorus was released from the bacterial cells during the anoxic stage. The amount of P-release in these two treatments was related to the concentrations of the carbon substrate used.     

改性钢渣的制备及其吸附除磷性能

研究了改性钢渣吸附除磷影响因素、等温吸附线特征和吸附动力学,并对生物处理后的出水进行吸附除磷研究。结果表明:在初始磷浓度10mg/L,投加量10g/L、pH为7时,改性钢渣吸附后总磷浓度为0.687mg/L,去除率达93%;改性钢渣对磷的吸附符合Langmuir模型,理论饱和吸附量是1.977mg/g,吸附动力学符合准二级动力学模型(R20.99);实际生活污水的吸附除磷中,投加量为50g/L,反应2h后出水总磷浓度达到《城镇污水处理厂污染物排放标准》(GB18918—2002)一级B标的排放要求。     

生物倍增工艺实际生产运行工况优化探讨

考察了生物倍增工艺处理城市污水的实际效能。结果表明,0.02～0.05kgCOD/(kgMLSS.d)的低负荷运行工况不利于对有机物的稳定去除,出水CODCr为69.8 mg/L,平均去除率仅为65.9%,若要满足有机物的排放标准要求,污泥负荷至少要维持在0.06kgCOD/(kgMLSS.d)以上;系统对氨氮的去除效果很好,氨氮去除率可达到100%;污泥沉降性能较好,SVI稳定在50～70;过低的进水C/N是同步脱氮除磷的制约因素,建议采用补充碳源和辅助化学除磷的方式来满足氮磷排放标准限值要求。     

Meeting the phosphorus consent with biological nutrient removal under UK winter conditions

It is estimated that up to 342 wastewater treatment plants (Wwtps) in England and Wales will require a phosphorus (P) consent by 2010. Although biological P removal is considered to be the most sustainable option for P removal, it has always been problematic for plants that remove both nitrogen and P due to the inadequate concentration of organic material during wet periods. Two biological nutrient removal (BNR) configurations, the Johannesburg (JHB) process and a combined JHB and five-stage Bardenpho process, were evaluated over a period of 2 years to assess the impact of sewage strength on bio-P removal. The JHB achieved an average effluent total phosphorus (TP) of 2.4 mg/L and the combined JHB and five-stage process averaged 1.4 mg/L effluent TP. The major problems affecting the performance of both configurations were: dissolved oxygen (DO) in the recycled mixed liquor, nitrate in the return activated sludge (RAS) and low influent biological oxygen demand (BOD) concentrations. Acetate dosing proved successful as a source of volatile fatty acids (VFAs) in the anaerobic zone during periods of low-strength sewage. An acetate dosing strategy based on the influent flow rate to the plant was found to be a simple and effective technique that ensured that a consent of <1 mg TP/L could be met.     

Anaerobic/oxic/anoxic granular sludge process as an effective nutrient removal process utilizing denitrifying polyphosphate-accumulating organisms

In a biological nutrient removal (BNR) process, the utilization of denitrifying polyphosphate-accumulating organisms (DNPAOs) has many advantages such as effective use of organic carbon substrates and low sludge production. As a suitable process for the utilization of DNPAOs in BNR, an anaerobic/oxic/anoxic granular sludge (AOAGS) process was proposed in this study. In spite of performing aeration for nitrifying bacteria, the AOAGS process can create anaerobic/anoxic conditions suitable for the cultivation of DNPAOs because anoxic zones exist inside the granular sludge in the oxic phase. Thus, DNPAOs can coexist with nitrifying bacteria in a single reactor. In addition, the usability of DNPAOs in the reactor can be improved by adding the anoxic phase after the oxic phase. These characteristics enable the AOAGS process to attain effective removal of both nitrogen and phosphorus. When acetate-based synthetic wastewater (COD: 600 mg/L, NH4-N: 60 mg/L, PO(4)-P: 10 mg/L) was supplied to a laboratory-scale sequencing batch reactor under the operation of anaerobic/oxic/anoxic cycles, granular sludge with a diameter of 500 microm was successfully formed within 1 month. Although the removal of both nitrogen and phosphorus was almost complete at the end of the oxic phase, a short anoxic period subsequent to the oxic phase was necessary for further removal of nitrogen and phosphorus. As a result, effluent concentrations of NH(4)-N, NO(x)-N and PO(4)-P were always lower than 1 mg/L. It was found that penetration depth of oxygen inside the granular sludge was approximately 100 microm by microsensor measurements. In addition, from the microbiological analysis by fluorescence in situ hybridization, existence depth of polyphosphate-accumulating organisms was further than the maximum oxygen penetration depth. The water quality data, oxygen profiles and microbial community structure demonstrated that DNPAOs inside the granular sludge may be responsible for denitrification in the oxic phase, which enables effective nutrient removal in the AOAGS process.     

某工业园区污水处理厂工艺诊断和优化运行研究

针对某工业园区污水处理厂出水COD、TN、NH_3-N和TP超标问题,采用标准化污水处理厂工艺运行诊断方法,结合工业废水特征,对污水处理厂二期运行现状进行评估分析,发现存在的问题主要为进水量超负荷运行、进水TP波动大且溶解性有机磷浓度高,预处理单元转鼓细格栅故障频繁、水解酸化池堵塞以及跌水复氧现象显著,生物处理单元生物除磷能力丧失、内回流混合液DO浓度高及温度对脱氮能力影响大。针对上述问题,提出三期工程扩建、预处理段设施改造、预处理段跌水复氧控制、化学除磷药剂投加点优化、内回流混合液DO控制和强化脱氮措施的季节性调整6项优化运行措施,保障出水稳定达标的同时实现节能降耗。     

Phosphorus recovery from sewage sludge with a hybrid process of low pressure wet oxidation and nanofiltration

Phosphorus recovery from sewage sludge will become increasingly important within the next decades due to depletion of mineral phosphorus resources. In this work a new process concept was investigated, which aims at realising phosphorus recovery in a synergistic way with the overall sewage sludge treatment scheme. This process combines a low pressure wet oxidation for sewage sludge decomposition as well as phosphorus dissolution and a nanofiltration process to separate phosphorus from heavy metals and obtain a clean diluted phosphoric acid, from which phosphorus can be recovered as clean fertiliser.It was shown that this process concept is feasible for sewage sludge for wastewater treatment plants that apply enhanced biological removal or precipitation with alumina salts for phosphorus removal. The critical parameter for phosphorus dissolution in the low pressure wet oxidation process is the iron concentration, while in the nanofiltration multi-valent cations play a predominant role.In total, a phosphorus recovery of 54% was obtained for an exemplary wastewater treatment plant. Costs of the entire process are in the same range as conventional sewage sludge disposal, with the benefit being phosphorus recovery and reduced emission of greenhouse gases due to avoidance of sludge incineration.