Anoxic Biological Phosphorus Uptake in A^2O Process

A lab-scale anaerobic-anoxic-oxic (A2O) process used to treat a synthetic brewage wastewater was investigated. The objectives of the study were to identify the existence of denitrifying phosphorus removing bacteria (DPB), evaluate the contribution of DPB to biological nutrient removal and enhance the denitrifying phosphorus removal in A2O bioreactors. Sludge analysis confirmed that the average anoxic P uptake accounted for approximately 70% the total amount of P uptake, and the ratio of anoxic P uptake rate to aerobic P uptake rate was 69%. In addition, nitrate concentration in the anoxic phase and different organic substrate introduced into the anaerobic phase had significant effect on the anoxic P uptake. Compared with conventional A2O processes, good removal efficiencies of COD, phosphorus, ammonia and total nitrogen (92.3%, 95.5%, 96% and 79.5%, respectively) could be achieved in the anoxic P uptake system, and aeration energy consumption was saved 25%. By controlling the nitrate recirculation flow in the anoxic zone, anoxic P uptake could be enhanced, which solved the competition for organic substrates among poly-P organisms and denitrifiers successfully under the COD limiting conditions. Therefore, in wastewater treatment plants the control system should be applied according to the practical situation to optimize the operation.

Removal of nitrogen and phosphorus in a combined A^2/O-BAF system with a short aerobic SRT

A bench-scale anaerobic/anoxic/aerobic process-biological aerated filter （A^2/O-BAF） combined system was carded out to treat wastewater with lower C/N and C/P ratios. The A^2/O process was operated in a short aerobic sludge retention time （SRT） for organic pollutants and phosphorus removal, and denitrification. The subsequent BAF process was mainly used for nitrification. The BAF effluent was partially returned to anoxic zone of the A^2/O process to provide electron acceptors for denitrification and anoxic P uptake. This unique system formed an environment for reproducing the denitdfying phosphate-accumulating organisms （DPAOs）. The ratio of DPAOs to phosphorus accumulating organisms （PAOs） could be maintained at 28% by optimizing the organic loads in the anaerobic zone and the nitrate loads into the anoxic zone in the A^2/O process. The aerobic phosphorus over-uptake and discharge of excess activated sludge was the main mechanism of phosphorus removal in the combined system. The aerobic SRT of the A^2/O process should meet the demands for the development of aerobic PAOs and the restraint on the nitrifiers growth, and the contact time in the aerobic zone of the A^2/O process should be longer than 30 min, which ensured efficient phosphorus removal in the combined system. The adequate BAF effluent return rates should be controlled with 1--4 mg/L nitrate nitrogen in the anoxic zone effluent of A^2/O process to achieve the optimal nitrogen and phosphorus removal efficiencies.

Toxicity Reduction of Municipal Wastewater by Anaerobic-anoxic-oxic Process

Objective This study was conducted to optimize the operational parameters of anaerobic-anoxic-oxic （A^2/O） processes to reduce the toxicity of municipal wastewater and evaluate its ability to reduce toxicity. Methods A luminescent bacterium toxicity bioassay was employed to assess the toxicity of influent and effluent of each reactor in the A2/O system. Results The optimum operational parameters for toxicity reduction were as follows： anaerobic hydraulic retention time （HRT） = 2.8 h, anoxic HRT = 2.8 h, aerobic HRT = 6.9 h, sludge retention time （SRT） = 15 days and internal recycle ratio （IRR） = 100%. An important toxicity reduction （%） was observed in the optimized A2/O process, even when the toluene concentration of the influent was 120.7 mg·L^-1. Conclusions The toxicity of municipal wastewater was reduced significantly during the A^2/O process. A^2/O process can be used for toxicity reduction of municipal wastewater under toxic-shock loading.

Full-scale evaluation of reversed A^(2)/O process for removal of multiple pollutants in sewage

This study evaluated the removal of multiple pollutants,i.e.,polybrominated diphenyl ethers(PBDEs),novel halogenated flame retardants(HFRs),sulfonamide antibiotics(SAs),and heavy metals(HMs),by a fullscale reversed A^(2)/O process in a sewage treatment plant(STP)in Guangzhou,China.The reversed A^(2)/O process demonstrated high removal efficiencies(REs)for total PBDEs(60.5%±4.3%),novel HFRs(98.4%±2.8%)and HMs(70.1%±1.2%),and a relatively low RE for SAs(25.0%±2.3%).BDE 209,the dominant PBDE congener,showed a high residual concentration(13.41±5.18 ng/L)in the suspended particulate matter(SPM)of treated effluents.So me novel HFRs,dechlorane plus(DP)and decabromodiphe nyl ethane(DBDPE),were detected in the SPM of the raw sewage(7.50±4.14 ng/L and 11.52±11.65 ng/L,respectively).The removal ofSAs was mainly through biodegradation in the activated sludge bioreactors(ASBs).Ofthe HMs,Mn and Ni exhibited the lowest REs(47.5%±2.2%and 35.0%±2.6%,respectively),while Cr and Cu showed the highest removal(REs>80%).In terms of treatment units in the reversed A^(2)/O process,ASBs showed the highest RE(27.8%)for the multiple pollutants.The information can aid in our understanding of removal properties of STPs on various pollutants and evaluating the ecological/health risks of STPs as point pollutant sources.

改良A^2/O工艺处理生活污水的脱氮除磷效果

在不改变污水厂总反应体积的情况下,为改善传统A^2/O工艺处理生活污水的脱氮除磷效果,通过减少缺氧池体积、在厌氧池前设置预缺氧池的方法建立了改良A^2/O工艺。试验结果表明,改良A^2/O工艺去除颗粒性COD的效果更好,可使较多的颗粒性COD转化为溶解性COD,且更易于满足脱氮除磷对碳源的需求,适宜处理低碳源污水。改良A^2/O工艺厌氧段出水TP为29. 11 mg/L、PHA含量为7. 7 mg/gMLSS,而传统A^2/O工艺厌氧段出水TP为18. 05 mg/L、PHA含量为6. 1 mg/g MLSS,厌氧段释磷效果较好,可见改良A^2/O工艺相比于传统A^2/O工艺有更好的碳源利用能力和除磷能力。

GPS-X模拟的三种A^2／O工艺脱氮除磷效果比较

通过使用GPS-X软件模拟传统A^2/O工艺、倒置A^2/O工艺和分点进水倒置A^2/O工艺的脱氮除磷效果,分析确定在建设投资、运行成本相同时处理效果最佳的工艺。根据模拟结果,三种工艺均实现了对有机物和营养物的有效去除,除倒置A^2/O工艺在低碳源进水时对TP的去除效果较差外,各工艺在低、中、高碳源进水时的各项出水水质指标均能够满足一级B排放标准。对COD、NH_4^+-N、TN、TP的去除率分别达到(92.07%~93.32%)、(95.26%~96.49%)、(72.92%~77.72%)和(81.50%~88%)。其中,两种倒置A^2/O工艺由于缺氧池碳源充足,脱氮效率较高,而传统A^2/O工艺由于厌氧池聚磷菌所需VFA充足和缺氧池反硝化除磷作用,除磷效果更好。

巴戟天中环烯醚萜苷和蒽醌在电喷雾离子源负离子模式下的质谱裂解行为

利用电喷雾-四极杆-飞行时间串联质谱(ESI-Q-TOF MS/MS)技术,在负离子模式下,探讨巴戟天中4种环烯醚萜苷和2种蒽醌成分的质谱裂解途径。通过[M-H]-获得化合物的相对分子质量信息,进一步对[M-H]-进行碰撞诱导解离,获得相应化合物的裂解途径。结果表明,环烯醚萜苷主要的裂解途径是首先脱去母环上的功能基团,如中性丢失H_2O、CO_2、CH_3COOH和糖单元等部分;其次是二氢吡喃环和糖环的断裂,m/z113、101为环烯醚萜苷母环断裂的特征碎片离子。蒽醌类化合物的裂解行为是连续失去CO,也可以失去CO_2。这些质谱裂解行为的研究有助于环烯醚萜苷和蒽醌类化合物的结构解析,也可为其他同类化合物的鉴定提供依据。

Effect of short-term atrazine addition on the performance of an anaerobic/anoxic/oxic process

In this study,an anaerobic/anoxic/oxic(A^(2)O)wastewater treatment process was implemented to treat domestic wastewater with short-term atrazine addition.The results provided an evaluation on the effects of an accidental pollution on the operation of a wastewater treatment plant(WWTP)in relation to Chemical Oxygen Demand(COD)and biological nutrient removal.Domestic wastewater with atrazine addition in 3 continuous days was treated when steady biological nutrient removal was achieved in the A^(2)O process.The concentrations of atrazine were 15,10,and 5 mg%L–1 on days 1,2 and 3,respectively.The results showed that atrazine addition did not affect the removal of COD.The specific NH4þoxidation rate and NO3–reduction rate decreased slightly due to the short-term atrazine addition.However,it did not affect the nitrogen removal due to the high nitrification and denitrification capacity of the system.Total nitrogen(TN)removal was steady,and more than 70%was removed during the period studied.The phosphorus removal rate was not affected by the short-term addition of atrazine under the applied experimental conditions.However,more poly-hydroxy-alkanoate(PHA)was generated and utilized during atrazine addition.The results of the oxygen uptake rate(OUR)showed that the respiration of nitrifiers decreased significantly,while the activity of carbon utilizers had no obvious change with the atrazine addition.Atrazine was not removed with the A^(2)O process,even via absorption by the activated sludge in the process of the short-term addition of atrazine.

基于多元功效成分的瓜蒌皮药材产地现代干燥加工方法研究

目的比较不同干燥方式对瓜蒌皮药材品质的影响,优选出适宜的瓜蒌皮药材产地现代干燥加工方法。方法收集安徽产新鲜瓜蒌皮,分别采用传统与现代产地加工干燥方法[40、50、60、70℃控温热风干燥,40、50、60、70℃微波真空干燥(真空度-0.08 MPa),50、60、70℃中短波红外干燥,-80℃真空冻干干燥,晒干,阴干]加工处理,结合干燥样品外观性状,以药效成分(5种黄酮类芦丁、木犀草苷、芹菜素-7-O-葡萄糖醛酸苷、芹菜素、橘红素,3种三萜类葫芦素D、葫芦素B、葫芦素E)、营养滋补类成分(2种糖类葡萄糖、果糖,18种氨基酸类苯丙氨酸、L-亮氨酸、异亮氨酸、L-色氨酸、γ-氨基丁酸、L-蛋氨酸、L-缬氨酸、脯氨酸、L-酪氨酸、反式-4-羟基-L-脯氨酸、L-苏氨酸、L-谷氨酸、L-谷氨酰胺、L-丝氨酸、L-天门冬酰胺、L-瓜氨酸、L-精氨酸、L-赖氨酸,12种核苷类胸腺嘧啶核苷、2′-脱氧尿苷、腺嘌呤、尿苷、腺苷、2′-脱氧肌苷、肌苷、胞嘧啶、鸟嘌呤、2′-脱氧鸟苷、胞苷、鸟苷)共40种资源性化学成分的组成及含量为评价指标,对不同干燥加工方法所得瓜蒌皮药材样品的品质进行综合评价。利用主成分分析(PCA)法,优选瓜蒌皮最佳现代干燥加工方法。结果不同干燥品中,药效成分及营养滋补类成分含量差异较大,其中果糖及葡萄糖质量分数分别为9.78%~21.32%、4.46%~15.63%;70℃微波真空干燥处理获得的瓜蒌皮所含黄酮类和四环三萜类成分总量最高,40℃控温热风干燥处理的总量最低。通过对14种不同干燥方式获得的瓜蒌皮样品进行综合评价分析,发现70℃控温热风干燥、70℃中短波红外干燥、-80℃真空冻干干燥、50℃微波真空干燥和60℃控温热风干燥方式获得的样品有效成分含量均优于传统晒干。结论结合药材的外观性状、色泽、质地、干燥时间及功效成分含量等因素,基于目前企业设备现状,建议70℃控温热风干燥为瓜蒌皮产地加工条件;基于未来新型设备的发展,70℃中短波红外干燥可作为瓜蒌皮产地加工的发展方向。研究结果将为瓜蒌皮药材产地加工的规范化和品质特征的形成提供借鉴。