艰氮和限磷对活性污泥合成聚羟基烷酸的影响

聚羟基烷酸（PHA）是微生物在不平衡营养条件下贮存的一种胞内聚合物，限磷和限氮两种方式均有助于活性污泥中的混合菌群合成PHA，研究考察了两种不同方式下活性污泥合成PHA的情况。实验结果表明，当C：N为125时，活性污泥中PHA的合成量达到细胞干重的59％；当c：P为750时，活性污泥积累的最大PHA含量占细胞干重的37％，说明限氮和限磷两种方式对活性污泥合成PHA均有很大影响，且限氮方式更有效。     

3种短链脂肪酸对活性污泥储存PHA的影响

采用经乙酸钠驯化培养具有一定聚羟基烷酸酯(PHA)储存能力的活性污泥,考察乙酸、丙酸和丁酸3种短链脂肪酸,以及乙酸、丁酸分别与丙酸按1∶1、1∶2、2∶1比例组合成的6种混合酸作为碳源时对活性污泥中PHA的储存和转化的影响。实验结果表明,在3种短链脂肪酸中,以丁酸为碳源得到活性污泥PHA储存量最高,为40.53 mg/g;在混合酸中,乙酸与丙酸按1∶2组合时,系统PHA储存量最高,为773.4 mg/g。混合酸相对于单一的脂肪酸碳源更有利于活性污泥储存PHA。在混合酸总量一定的条件下,随着丙酸比例的增加,乙酸与丙酸混合比丁酸与丙酸混合更有利于微生物的PHA储存。     

不同比例乙酸和丙酸对活性污泥微生物合成聚羟基脂肪酸酯的影响

聚羟基脂肪酸酯(PHA)是一种生物可降解塑料,利用活性污泥合成PHA具有节约成本、操作方便的优点。研究选择污泥发酵液挥发性脂肪酸(VFAs)中比重相对较高的乙酸和丙酸作为碳源自配营养液,深入研究不同质量浓度比对PHA合成的影响。结果表明,乙酸为主要碳源时更有利于PHA的合成,最大合成量12.3%出现在乙酸作为唯一碳源的条件下。此外,PHA合成量随着底物中有机酸比重的增加而增加,充分展现了利用挥发性脂肪酸大量合成PHA的良好前景。     

循环式活性污泥工艺协同处理榨菜废水与城镇污水脱氮效果

利用CASS工艺协同处理高盐高氮榨菜有机废水和生活污水,针对协同处理碳源不足问题,提出以榨菜废水和甲醇作为碳源的两种碳源投加方案,对比分析了CASS工艺在运行周期为8 h、排水比为30%、回流比为100%、预处理后的榨菜废水掺入比为20%的条件下,分别以榨菜废水和甲醇补充碳源及不外加碳源3种情况的脱氮效果。实验结果表明,不外加碳源时,协同处理进水C/N小于3∶1,系统脱氮效果差,出水总氮不达标;以榨菜废水和甲醇为碳源提高C/N至4∶1～5∶1时,系统脱氮效果提高,出水总氮满足GB18918-2002一级B标排放标准;盐度的变化对微生物活性产生的抑制作用,当盐度升高0.1%±0.02%时,微生物系统恢复时间为10 d,而当盐度降低0.1%±0.02%时,微生物系统恢复时间为15 d。     

好氧反硝化菌强化序批式活性污泥反应器处理生活污水

研究了好氧反硝化菌强化序批式活性污泥反应器(SBR1)处理生活污水的性能,同时以只接种相同量普通活性污泥的序批式活性污泥反应器(SBR2)作为对照组。结果表明:(1)反应前21天启动期间,SBR1对污水COD、NH+4-N和TN的平均去除率分别可达到77.79%、94.96%、63.21%,对COD和TN的平均去除率明显好于SBR2。(2)当C/N为4∶1(质量比,下同)和6∶1时,SBR1对COD和TN的去除率明显高于SBR2;当C/N为8∶1时,SBR1对COD和TN的去除效果达到最好,对两者的平均去除率分别达到85.31%和61.14%;当C/N为10∶1和12∶1时,两反应器对废水COD去除效果的差距缩小,但SBR1对TN的平均去除率分别为58.98%和51.64%,明显高于SBR2。(3)SBR1投加的好氧反硝化菌适应较低的C/N环境,且能在生活污水中快速增殖,保持了很好的污泥悬浮液浓度和沉降性能,在35d形成成熟的颗粒污泥。     

活性污泥法合成可生物降解塑料的工程化可行性探讨

细菌发酵法仍是目前合成可生物降解塑料(PHA)的主要方法,但实现其工业化生产的最大瓶颈是生产费用较为昂贵,而活性污泥法因独具的优点,有望成为较为经济、具有良好前景的PHA生物合成方法。对利用活性污泥法合成PHA的工程化可行性进行了探讨,主要分析了活性污泥法的PHA合成代谢机制、工艺优化和PHA积累水平,以及方法的技术经济可行性。最后指出,活性污泥法合成PHA不仅在技术、投资和生产费用方面较细菌发酵法更具竞争力,而且能在有效去除污染物的同时积累PHA,具有很好的推广价值和应用前景。     

硝态氮为惟一氮源时异养微生物增长特性

采用SBR研究了缺氧条件下硝态氮为惟一氮源时异养微生物的增长特性。结果表明,异养微生物能利用硝态氮作为氮源进行增殖。当进水COD浓度为1 400 mg/L,硝态氮浓度为280 mg/L时,COD和硝态氮的去除率分别达到97%和99%;污泥中微生物的含氮量为8.8%,低于常规利用氨氮作为氮源的微生物;在实验条件下活性污泥的产率系数为0.30 g VSS/g COD。反硝化菌可利用硝态氮作为氮源进行细胞合成对含硝氮的废水处理具有重要意义。一方面由于无需投加氨氮降低了废水处理成本,另一方面由于污泥产率低,降低了污泥处理成本。     

新型污染物纳米氧化铜对生物脱氮除磷的影响及机制探究

在序批式活性污泥反应器(SBR)中探究了新型污染物纳米氧化铜(CuO NP)短期和长期暴露对实际废水生物脱氮除磷的影响并分析了影响机制。结果表明:0~10.0mg/L CuO NP短期暴露对生物脱氮除磷效率及活性污泥性能影响不明显;经过30d长期暴露,CuO NP对生物脱氮除磷效率产生了严重的抑制作用,且CuO NP浓度越高,抑制效果越明显。CuO NP由0mg/L增加到10.0mg/L时,生物脱氮效率由90.6%下降至79.8%,生物除磷效率由91.6%下降至70.5%。CuO NP长期暴露能够抑制胞内聚合物聚羟基脂肪酸酯(PHA)的合成,近而减少其氧化分解产生的能量。此外,CuO NP还能抑制活性污泥呼吸速率。在10.0mg/L CuO NP作用下,呼吸抑制率为69.0%。     

Cupriavidus necator(DSM428)利用地沟油合成PHA的条件优化

聚羟基脂肪酸酯(PHA)是一种在细胞体内合成的天然高分子生物材料,由于其具有可降解性,因此可以代替传统塑料,已被广泛应用于生产生活中。选用Cupriavidus necator(DSM428)作为实验菌株,利用价格相对低廉的地沟油作为细菌生长的碳源,考察了p H、温度、培养时间、C/N(质量比)对PHA产生量的影响,同时对其结构及热学性质进行分析。通过实验发现,PHA最佳合成条件是p H值为8,温度为30℃,培养时间为84 h,C/N为20∶1.5,PHA最大产量范围为7~9 g/L。     

悬浮填料缺氧成膜过程及其强化TN去除效能

温度和碳源是影响污水处理厂反硝化脱氮效果的2个重要因素,通过对SPR-1型悬浮填料缺氧挂膜,并分别对活性污泥系统、悬浮填料系统和悬浮填料+活性污泥复合系统的反硝化效果及温度和碳源对脱氮的影响进行了实验研究。结果表明:利用好氧预挂膜结合快速排泥法,能在30 d内完成缺氧挂膜,填料附着生物量达40.4 mg VSS/g载体;投加悬浮填料可增强复合系统在低温和低碳源条件下的反硝化能力。在填充率为20%的复合系统中,当温度为7、15、20和25℃时,反硝化速率分别提高42.9%、31.1%、21.4%和10.5%,硝酸盐去除率在7、15、20℃条件下分别提高了58.1%、9.8%和3.8%;当温度在(20±1)℃,C/N为1、2、3和6时,复合系统反硝化速率均高于活性污泥系统,硝酸盐去除率分别提高145.8%、81.5%、16.3%和6.1%。在低温和低碳源条件下利用悬浮填料强化活性污泥系统反硝化效果更为显著。     

Effects of nitrogen and phosphorus limitation on the activated sludge biomass in a kraft mill biotreatment system.

Unlike wastewater, pulp and paper mill effluents are generally severely deficient in bioavailable nitrogen and phosphorus. The influence of nitrogen and phosphorus limitations on steady-state or typical pulp and paper mill activated sludge floc properties and performance was studied using a bioreactor-fed synthetic raw mill effluent and seeded with mill activated sludge. Limitation of either nitrogen or phosphorus decreased growth, five-day biochemical oxygen demand, and suspended solids removal. Nitrogen limitation greatly enhanced activated sludge floc poly-beta3-hydroxybutyrate (PHB), but not carbohydrate or extracellular polymeric substances (EPS). In contrast, phosphorus limitation increased total floc carbohydrate and EPS, but not PHB. The flocs showed little ability to store either nitrogen or phosphorus. Nitrogen limitation, but not phosphorus limitation, produced much more negative net floc surface charge, increasing fines, while phosphorus limitation, but not nitrogen limitation, increased the floc bound water content and surface hydrophobicity and decreased fines.     

营养限制对厌氧序批操作反应器的影响及其恢复重建过程

研究了在厌氧条件下以葡萄糖为基质的序批操作反应器(ASBR)中营养物浓度限制对基质吸收和储存的影响及其恢复重建过程。结果表明,营养物限制条件下,发酵细菌表现为过量吸收基质并储存为糖原,形成隐性增殖以维持其细胞的正常结构和代谢功能;而甲烷菌由于无储存能力,其表现为活性逐渐降低。短期营养限制条件下(1个周期),基质中无磷时,储存量增加29%;基质中无氮时,储存量增加90%;基质中既无氮也无磷时,储存量增加26%。长期(31个周期)营养限制(基质中氮磷含量减小50%)下,胞内储存糖原量可高达正常状态下的4.8倍,但甲烷活性减少为正常状态下的17.78%。营养物限制对发酵细菌影响较小,对甲烷菌影响较大。将氮磷浓度恢复正常后,反应器的产甲烷能力恢复较快,出水COD经31周期后恢复正常,而胞内糖原在85周期后恢复正常。     

Recovery of polyhydroxyalkanoate from activated sludge in an enhanced biological phosphorus removal bench-scale reactor.

A sequencing batch reactor was used to study the possibility of harvesting polyhydroxyalkanoate (PHA) from enhanced biological phosphorus removal (EBPR) processes without compromising treatment quality. Because, in EBPR, the highest PHA concentrations are observed after exposure of the sludge to anaerobic conditions, PHA accumulation was evaluated with collection of waste activated sludge (WAS) at the end of the anaerobic stage, in addition to the traditional removal after the aerobic stage. The system achieved good phosphorus removal, regardless of the point of WAS collection. When sludge was harvested at the end of the anaerobic stage, the PHA content of the sludge ranged from 7 to 16 mg PHA/100 mg mixed liquor volatile suspended solids. Although this level of PHA production is below levels obtained with pure cultures, the demonstrated ability to harvest PHA, while simultaneously satisfying phosphorus removal in an EBPR process, is a key initial step towards of the use of wastewater treatment plants for PHA production.     

Secondary nitrogen limitation in a subtropical lake impacted by non-point source agricultural pollution

A 20-year history of nutrient limitation was quantified for Lake Okeechobee, a nutrient-impacted lake in Florida, USA. Limiting status (nitrogen versus phosphorus) was estimated from deviations between trophic state index (TSI) parameters, calculated from routine monitoring data. The lake is presently nitrogen-limited. However, historical trends in the TSI deviations indicate that contemporary nitrogen limitation is a secondary, unnatural condition that has arisen due to excessive phosphorus loading. Prior to 1980, there was evidence of lake-wide limitation by phosphorus, rather than nitrogen. The finding of secondary nitrogen limitation in Lake Okeechobee has important management implications. Phosphorus loads are presently being reduced in order to reduce in-lake concentrations and create phosphorus-limited conditions (nitrogen limitation is undersirable because it has favored bloom-forming cyanobacteria). The present results indicate that this long-term management goal is ecologically sound; it is consistent with the concept of restoration of the lake.     

Investigating phosphorus limitation in a fixed bed filter with phosphorus and nitrogen profile measurements

In 2000, the European Union adopted the European Water Framework Directive (WFD) (European Commission, 2000). The WFD focuses on increasingly stringent nutrient standards including ultra low nitrogen (< 2.2 mg N-total/L) and phosphorus concentrations (< 0.15 mg total phosphorus/L) in receiving surface waters and in relevant point sources like wastewater treatment plant (WWTP) effluent. Expansion of WWTPs with advanced post-treatment processes, like effluent filtration, is widely proposed to meet possible future effluent discharge standards. When combining biological nitrate-nitrogen and chemical phosphorus removal in one filter, phosphorus limitation in the denitrifying process may occur. This study investigated where in the filter bed and under which conditions phosphorus limitation occurs. Profile measurements for nitrate, nitrite, and orthophosphorus (PO4-P) combined with chemical oxygen demand (COD) and 02 were conducted. Results showed that the required PO4-P/NOx-N ratio is approximately 0.006 mg/mg after phosphorous precipitation and flocculation. Profile measurements have proven to be an applicable and useful tool. It showed how nitrate and orthophosphorus are removed through the filter bed based on the PO4-P/NOx-N ratio. When orthophosphorus is removed more rapidly and efficiently compared to nitrate, the PO4-P/NOx-N ratio decreases. When PO4-P/NOx-N ratio thresholds are approximately 0.006 mg/mg for a certain period of time and water temperatures varied significantly, orthophosphorus limitation may occur. Changing the filter-bed configuration or decreasing the coagulant dosage can prevent limitation of the denitrifying process because of a phosphorous shortage.     

沸石粉在污泥生态床中的应用研究

研究了不同沸石粉投加比例对污泥脱水、沉降、干化时间、污泥生态床中植物根部干重的影响,最终选定沸石粉投加比例为6%。在此投加比例下,对污泥生态床中的氮磷含量进行了测定,结果表明,黄花鸢尾床与芦苇床,总磷含量下降分别为13.2%和12.2%;总氮含量下降分别为48.3%和49.2%;硝氮含量下降分别为67.2%和70.2%。     

造纸白泥和粉煤灰的添加对污泥消化液中氮磷回收的影响

污泥厌氧消化液中含有丰富的氮磷，若直接排放到环境中，将会对附近水体造成严重污染。由于消化液中Mg^2＋和Ca^2＋的含量很低，严重影响了氮磷的回收效果。把造纸白泥和粉煤灰引入到污泥厌氧消化液氮磷的回收当中，可以明显地提升消化液pH和提高PO4^3-P和NH3-N回收率。实验结果表明：当造纸白泥添加量为4g／（L·h）时，曝气12h后，pH可达10．19，此时PO4^3-P和NH3-N回收率分别达到64％和45％；而当粉煤灰添加量为4g／（L·h）时，曝气12h后，pH达到9．63，PO4^3-P和NH3-N回收率分别为46％和41％。但仅用曝气方式处理，12h后，pH值仅为8．52，PO4^3-P和NH3-N回收率分别只有20％和18％。实验结果还表明，水力停留时间（HRT）越大，pH上升速度越快，幅度越大，氮磷的回收效果就越好。     

Optimization of enhanced biological phosphorus removal after periods of low loading.

Enhanced biological phosphorus removal is a well-established technology for the treatment of municipal wastewater. However, increased effluent phosphorus concentrations have been reported after periods (days) of low organic loading. The purpose of this study was to evaluate different operating strategies to prevent discharge of effluent after such low-loading periods. Mechanisms leading to these operational problems have been related to the reduction of polyphosphate-accumulating organisms (PAOs) and their storage compounds (polyhydroxy alkanoates [PHA]). Increased effluent phosphorus concentrations can be the result of an imbalance between influent loading and PAOs in the system and an imbalance between phosphorus release and uptake rates. The following operating conditions were tested in their ability to prevent a reduction of PHA and of overall biomass during low organic loading conditions: (a) unchanged operation, (b) reduced aeration time, (c) reduced sludge wastage, and (d) combination of reduced aeration time and reduced sludge wastage. Experiments were performed in a laboratory-scale anaerobic-aerobic sequencing batch reactor, using acetate as the carbon source. Without operational adjustments, phosphorus-release rates decreased during low-loading periods but recovered rapidly. Phosphorus-uptake rates also decreased, and the recovery typically required several days to increase to normal levels. The combination of reduced aeration time and reduced sludge wastage allowed the maintenance of constant levels of both PHA and overall biomass. A mathematical model was used to explain the influence of the tested operating conditions on PAO and PHA concentrations. While experimental results were in general agreement with model predictions, the kinetic expression for phosphorus uptake deviated significantly for the first 24 hours after low-loading conditions. Mechanisms leading to these deviations need to be further investigated.     

剩余污泥发酵产酸特征及基质释放规律研究

剩余污泥发酵既能实现污泥减量,又能获得污水生物脱氮除磷所需的挥发性脂肪酸VFAs等。采用序批式污泥发酵实验,在(30±1)℃的条件下,研究剩余污泥投配比对序批式污泥发酵系统污泥减量、产酸以及基质释放过程的影响,探索VFAs生成最大化的条件。实验结果表明:投加接种污泥不能明显提高序批式污泥发酵系统剩余污泥的减量效果,但可以改善污泥的产酸特性;当污泥投配比大于50%时,发酵过程中将出现2个VFAs浓度峰,且第二次峰浓度更大;较为理想的序批式污泥发酵投配比是60%~80%、发酵时间为5 d或25 d,前者VFAs表观转化率最大(约24%),后者发酵液中VFAs浓度最高(约600 mg/L);发酵过程中,NH4+-N总体呈上升趋势,磷浓度发酵5 d时达到最大值。