新型双泥生物反硝化除磷脱氮工艺

在对生物脱氮与除磷机理进行深入研究后发现，生物脱氮与除磷是两个相对独立而又相互交叉的生理过程，其交叉点是部分聚磷菌在缺氧状态下的反硝化吸磷脱氮。在此基础上提出的新型双泥生物反硝化除磷脱氮工艺（由两个不同功能的SBR反应器组成）成功地解决了硝化菌与聚磷菌的泥龄之争。反硝化与聚磷菌厌氧释磷的矛盾等难题，该工艺运行稳定且处理效果良好，特别适合于处理BOD5/TP值低的污水。     

A novel post denitrification configuration for phosphorus recovery using polyphosphate accumulating organisms

Enhanced biological phosphorus removal (EBPR) has been widely used to remove phosphorus (P) from wastewater. In this study we report a novel modification to the EBPR approach, namely enhanced biological phosphorus removal and recovery (EBPR-r) that facilitates biological recovery of P from wastewater using a post denitrification configuration. The novel approach consists of two major steps. In the first step, a biofilm of phosphorus accumulating organisms (PAOs) is exposed to a wastewater stream in the absence of active aeration, during which P is taken up by the biofilm using nitrate and residual dissolved oxygen as electron acceptors. Thus, P and nitrogen (N) removal from wastewater is achieved. During the second step, the P enriched biofilm is exposed to a smaller recovery stream supplemented with an external carbon source to facilitate P release under anaerobic conditions. This allows P to be recovered as a concentrated liquid. The EBPR-r process was able to generate a P recovery stream four time more concentrated (28 mg-P/L) than the wastewater stream (7 mg-P/L), while removing nitrate (denitrification) from the wastewater stream. Repeated exposure of the biofilm (10 P-uptake and release cycles) to a recovery stream yielded up to 100 mg-P/L. Overall, EBPR-r is the first post denitrification strategy that can also facilitate P recovery during secondary wastewater treatment.     

Floc-based sequential partial nitritation and anammox at full scale with contrasting N2O emissions

New Activated Sludge (NAS^®) is a hybrid, floc-based nitrogen removal process without carbon addition, based on the control of sludge retention times (SRT) and dissolved oxygen (DO) levels. The aim of this study was to examine the performance of a retrofitted four-stage NAS^® plant, including on-line measurements of greenhouse gas emissions (N₂O and CH₄). The plant treated anaerobically digested industrial wastewater, containing 264 mg N L⁻¹, 1154 mg chemical oxygen demand (COD) L⁻¹ and an inorganic carbon alkalinity of 34 meq L⁻¹. The batch-fed partial nitritation step received an overall nitrogen loading rate of 0.18-0.22 kg N m⁻³ d⁻¹, thereby oxidized nitrogen to nitrite (45-47%) and some nitrate (13-15%), but also to N₂O (5.1-6.6%). This was achieved at a SRT of 1.7 d and DO around 1.0 mg O₂ L⁻¹. Subsequently, anammox, denitrification and nitrification compartments were followed by a final settler, at an overall SRT of 46 d. None of the latter three reactors emitted N₂O. In the anammox step, 0.26 kg N m⁻³ d⁻¹ was removed, with an estimated contribution of 71% by the genus Kuenenia, which constituted 3.1% of the biomass. Overall, a nitrogen removal efficiency of 95% was obtained, yielding a dischargeable effluent. Retrofitting floc-based nitrification/denitrification with carbon addition to NAS^® allowed to save 40% of the operational wastewater treatment costs. Yet, a decrease of the N₂O emissions by about 50% is necessary in order to obtain a CO₂ neutral footprint. The impact of emitted CH₄ was 20 times lower.     

High-rate denitrification using polyethylene glycol gel carriers entrapping heterotrophic denitrifying bacteria

This study evaluated the nitrogen removal performance of polyethylene glycol (PEG) gel carriers containing entrapped heterotrophic denitrifying bacteria. A laboratory-scale denitrification reactor was operated for treatment of synthetic nitrate wastewater. The nitrogen removal activity gradually increased in continuous feed experiments, reaching 4.4 kg N m⁻³ d⁻¹ on day 16 (30 °C). A maximum nitrogen removal rate of 5.1 kg N m⁻³ d⁻¹ was observed. A high nitrogen removal efficiency of 92% on average was observed at a high loading rate. In batch experiments, the denitrifying gel carriers were characterized by temperature. Nitrate and total nitrogen removal activities both increased with increasing temperature, reaching a maximum at 37 and 43 °C, respectively. Apparent activation energies for nitrate and nitrite reduction were 52.1 and 71.9 kJ mol⁻¹, respectively. Clone library analysis performed on the basis of the 16S rRNA gene revealed that Hyphomicrobium was mainly involved in denitrification in the methanol-fed denitrification reactors.     

The role of the microbial stringent response in excess intracellular accumulation of phosphorous in mixed consortia fed synthetic wastewater

Four bench-scale sequencing batch reactors (SBRs) seeded with activated sludge were operated under either fully oxic or anoxic/oxic conditions and fed synthetic wastewater containing either peptone or acetate. The function of each reactor was assessed through the measure of (i) soluble chemical oxygen demand, orthophosphate, ammonia, and nitrate; and (ii) biomass concentrations of phosphorus, polyhydroxyalkanoate, guanosine tetraphosphate, adenosine monophosphate, adenosine diphosphate, and adenosine triphosphate. In all four reactors, the biomass concentration of phosphorous was correlated statistically with the biomass concentration of ppGpp. The microbial consortia in all four reactors removed an appreciable quantity of phosphorous from solution (67-99%), and the net quantity of phosphorous removed from solution corresponded to the net increase in the biomass concentration of phosphorous. Hence, the microbial stringent response (MSR) was associated with excess intracellular accumulation of phosphorous in mixed microbial consortia fed synthetic wastewater. With recognition of the potential role of the MSR in the removal of soluble phosphorous from wastewater, additional research may lead to further optimization of treatment technologies and the development of new treatment systems for the biological removal of phosphorus from wastewater.     

Complete nutrient recovery from source-separated urine by nitrification and distillation

In this study we present a method to recover all nutrients from source-separated urine in a dry solid by combining biological nitrification with distillation. In a first process step, a membrane-aerated biofilm reactor was operated stably for more than 12 months, producing a nutrient solution with a pH between 6.2 and 7.0 (depending on the pH set-point), and an ammonium to nitrate ratio between 0.87 and 1.15 gN gN⁻¹. The maximum nitrification rate was 1.8 ± 0.3 gN m⁻² d⁻¹. Process stability was achieved by controlling the pH via the influent. In the second process step, real nitrified urine and synthetic solutions were concentrated in lab-scale distillation reactors. All nutrients were recovered in a dry powder except for some ammonia (less than 3% of total nitrogen). We estimate that the primary energy demand for a simple nitrification/distillation process is four to five times higher than removing nitrogen and phosphorus in a conventional wastewater treatment plant and producing the equivalent amount of phosphorus and nitrogen fertilizers. However, the primary energy demand can be reduced to values very close to conventional treatment, if 80% of the water is removed with reverse osmosis and distillation is operated with vapor compression. The ammonium nitrate content of the solid residue is below the limit at which stringent EU safety regulations for fertilizers come into effect; nevertheless, we propose some additional process steps that will increase the thermal stability of the solid product.     

SBR无厌氧段生物强化除磷的诱导研究

采用SBR工艺处理人工配水,考察了进水COD及氨氮浓度、C/N值、好氧时间对诱导无厌氧段生物强化除磷的影响.结果表明,当以醋酸钠为碳源、进水COD和氨氮分别为100和5mg/L、C/N值为20时,对在A/O运行方式下表现为厌氧释磷、好氧超量吸磷的SBR,逐渐缩短其厌氧时间且保持好氧时间为135 min后,好氧吸磷现象并不会消失,仅是吸磷量略有降低.该除磷现象的发生是系统微生物经过特定诱导的结果.     

Kinetic competition between phosphorus release and denitrification on sludge under anoxic condition

The kinetic behaviors of simultaneous phosphorus release and denitrification on sludge were investigated under anoxic condition. A phosphorus enriched sludge produced from Anaerobic-Anoxic-Oxic (AnAO) process under various SRT (5, 10 and 15 days) operation conditions was carried out in a series of batch tests. Experimental results indicated that the available organic substrate determined the kinetic behaviors of phosphorus release/uptake and denitrification. The simultaneous phosphorus release and denitrification demonstrated a kinetic competition under anoxic conditions in the presence of an available organic substrate. When the substrate was abundant, sludge was under “releasable-phosphorus-limited” condition; phosphorus release rate decreased slightly by nitrate inhibition. However, nitrate significantly inhibited phosphorus release when sludge was under “initial-substrate-limited” condition. Moreover, the sludge's phosphorus contents (as created by different SRT processes) dominated the kinetics of competition between phosphorus release and denitrification. The sludge with a high phosphorus content had a higher phosphorus release rate in accordance with a lower denitrification rate. Additionally, the substrate sequestrated rate markedly increased under the condition of simultaneous phosphorus release and denitrification. Finally, a preliminary metabolism model of denitrifying phosphorus removal bacteria was proposed, and found to be capable of adequately accounting for simultaneous phosphorus release and denitrification under anoxic conditions.     

Distributions and activities of ammonia oxidizing bacteria and polyphosphate accumulating organisms in a pumped-flow biofilm reactor

The spatial distributions and activities of ammonia oxidizing bacteria (AOB) and polyphosphate accumulating organisms (PAOs) were investigated for a novel laboratory-scale sequencing batch pumped-flow biofilm reactor (PFBR) system that was operated for carbon, nitrogen and phosphorus removal. The PFBR comprised of two 16.5 l tanks (Reactors 1 and 2), each with a biofilm module of 2 m² surface area. To facilitate the growth of AOB and PAOs in the reactor biofilms, the influent wastewater was held in Reactor 1 under stagnant un-aerated conditions for 6 h after feeding, and was then pumped over and back between Reactors 1 and 2 for 12 h, creating aerobic conditions in the two reactors during this period; as a consequence, the biofilm in Reactor 2 was in an aerobic environment for almost all the 18.2 h operating cycle. A combination of micro-sensor measurements, molecular techniques, batch experiments and reactor studies were carried out to analyse the performance of the PFBR system. After 100 days operation at a filtered chemical oxygen demand (COD_f) loading rate of 3.46 g/m² per day, the removal efficiencies were 95% COD_f, 87% TN_f and 74% TP_f. While the PFBR microbial community structure and function were found to be highly diversified with substantial AOB and PAO populations, about 70% of the phosphorus release potential and almost 100% of the nitrification potential were located in Reactors 1 and 2, respectively. Co-enrichment of AOB and PAOs was realized in the Reactor 2 biofilm, where molecular analyses revealed unexpected microbial distributions at micro-scale, with population peaks of AOB in a 100–250 μm deep sub-surface zone and of PAOs in the 0–150 μm surface zone. The micro-distribution of AOB coincided with the position of the nitrification peak identified during micro-sensor analyses. The study demonstrates that enrichment of PAOs can be realized in a constant or near constant aerobic biofilm environment. Furthermore, the findings suggest that when successful co-enrichment of AOB and PAOs occur in biofilm environments, such as in the PFBR system, they do so at different zone depths in the biofilm.     

Strategies for lipids and phenolics degradation in the anaerobic treatment of olive mill wastewater

Strategies are proposed for the anaerobic treatment of lipid and phenolic-rich effluents, specifically the raw olive mill wastewater (OMW). Two reactors were operated under OMW influent concentrations from 5 to 48 g COD L⁻¹ and Hydraulic Retention Time between 10 and 5 days. An intermittent feeding was applied whenever the reactors showed a severe decay in the methane yield. This strategy improved the mineralization of oleate and palmitate, which were the main accumulated Long-Chain Fatty Acids (LCFA), and also promoted the removal of resilient phenolic compounds, reaching remarkable removal efficiencies of 60% and 81% for two parallel reactors at the end of a feed-less period. A maximum biogas production of 1.4 m³ m⁻³ d⁻¹ at an Organic Loading Rate of 4.8 kg COD m⁻³ d⁻¹ was obtained. Patterns of individual LCFA oxidation during the OMW anaerobic digestion are presented and discussed for the first time. The supplementation of a nitrogen source boosted immediately the methane yield from 21 and 18 to 76 and 93% in both reactors. The typical problems of sludge flotation and washout during the anaerobic treatment of this oily wastewater were overcome by biomass retention, according to the Inverted Anaerobic Sludge Blanket (IASB) reactor concepts. This work demonstrates that it is possible to avoid a previous detoxification step by implementing adequate operational strategies to the anaerobic treatment of OMW.     

Influence of manganese and ammonium oxidation on the removal of 17 alpha-ethinylestradiol (EE2)

Flow-through reactors with manganese oxides were examined for their capacity to remove 17α-ethinylestradiol (EE2) at μg L⁻¹ and ng L⁻¹ range from synthetic wastewater treatment plant (WWTP) effluent. The mineral MnO₂ reactors removed 93% at a volumetric loading rate (B_V) of 5 μg EE2 L⁻¹ d⁻¹ and from a B_V of 40 μg EE2 L⁻¹ d⁻¹ on, these reactors showed 75% EE2 removal. With the biologically produced manganese oxides, only 57% EE2 was removed at 40 μg EE2 L⁻¹ d⁻¹. EE2 removal in the ng L⁻¹ range was 84%. The ammonium present in the influent (10 mg N L⁻¹) was nitrified and ammonia-oxidizing bacteria (AOB) were found to be of prime importance for the degradation of EE2. Remarkably, EE2 removal by AOB continued for a period of 4 months after depleting NH₄⁺ in the influent. EE2 removal by manganese-oxidizing bacteria was inhibited by NH₄⁺. These results indicate that the metabolic properties of nitrifiers can be employed to polish water containing EE2 based estrogenic activity.     

Performance of IFAS wastewater treatment processes for biological phosphorus removal

Integrated fixed film activated sludge (IFAS) is a promising process for the enhancement of nitrification and denitrification in conventional activated sludge systems that need to be upgraded for biological nutrient removal (BNR), particularly when they have space limitations or need modifications that will require large monetary expenses. Several studies have reported successful implementations of IFAS at temperate zone wastewater treatment facilities, typically by placement of fixed film media into aerobic zones. However, nearly all of the implementations have not included enhanced biological phosphorus removal (EBPR) in the upgraded systems. This is possibly because the treatment plants have been operated at low mixed liquor mean cell residence times (MCRTs), and EBPR would wash out of the systems at the low temperatures encountered, making it difficult to maintain EBPR. The primary objective of this study was to investigate the incorporation of EBPR into IFAS systems, and study the interactions between the fixed biomass and the mixed liquor suspended solids with respect to substrate competition and nutrient removal efficiencies. Three pilot-scale UCT/VIP configuration systems were used, one as a control and the other two with Bioweb media integrated into some of the anoxic and aerobic reactors. The systems were operated at different MCRTs, and influent COD/TP ratios, and with split influent flows. The experimental results confirmed that EBPR could be incorporated successfully into IFAS systems, but the redistribution of biomass resulting from the integration of fixed film media, and the competition of organic substrate between EBPR and denitrification would affect performances. Also, the integration of fixed film media into the anoxic reactors affected performances differently from media in aerobic reactors.     

进水氨氮对厌氧同步脱氮除硫工艺的影响

通过比较含氨氮和不含氨氮两种进水水质条件下接种物不同的两个反应器的脱氮除硫特性,研究进水氨氮对厌氧同步脱氮除硫性能的影响。结果表明,进水未加氨氮的反应器对硫化物和硝态氮的去除率均高达95%,当加入氨氮后,仅有40%～50%的硝态氮被去除,消耗1 g硫化物所还原的硝态氮量减少,去除硝态氮的能力降低了近50%,然而对硫化物的去除率仍维持在90%左右,表明脱氮过程比脱硫过程受进水氨氮的影响大。扫描电镜观察结果证实,当进水中存在氨氮时硫化物的毒性增大,杀死了大量的脱氮硫杆菌,降低了硫化物转化为单质硫的能力,干扰了系统的反硝化脱氮过程,这是导致体系脱氮能力降低的主要原因。     

Long-term impact of anaerobic reaction time on the performance and granular characteristics of granular denitrifying biological phosphorus removal systems

Removal of nitrogen and phosphorus (P) from wastewater is successfully and widely practiced in systems employing both granular sludge technology and enhanced biological P removal (EBPR) processes; however, the key parameter, anaerobic reaction time (AnRT), has not been thoroughly investigated. Successful EBPR is highly dependent on an appropriate AnRT, which induces carbon and polyphosphate metabolism by phosphorus accumulating organisms (PAOs). Therefore, the long-term impact of AnRT on denitrifying P removal performance and granular characteristics was investigated in three identical granular sludge sequencing batch reactors with AnRTs of 90 (R1), 120 (R2) and 150 min (R3). The microbial community structures and anaerobic stoichiometric parameters related to various AnRTs were monitored over time. Free nitrite acid (FNA) accumulation (e.g., 0.0008–0.0016 mg HNO₂–N/L) occurred frequently owing to incomplete denitrification in the adaptation period, especially in R3, which influenced the anaerobic/anoxic intracellular intermediate metabolites and activities of intracellular enzymes negatively, resulting in lower levels of poly-P and reduced activity of polyphosphate kinase. As a result, the Accumulibacter-PAOs population decreased from 51 ± 2.5% to 43 ± 2.1% when AnRT was extended from 90 to 150 min, leading to decreased denitrifying P removal performance. Additionally, frequent exposure of microorganisms to the FNA accumulation and anaerobic endogenous conditions in excess AnRT cases (e.g., 150 min) stimulated increased extracellular polymeric substances (EPS) production by microorganisms, resulting in enhanced granular formation and larger granules (size of 0.6–1.2 mm), but decreasing anaerobic PHA synthesis and glycogen hydrolysis. Phosphorus removal capacity was mediated to some extent by EPS adsorption in granular sludge systems that possessed more EPS, longer AnRT and relatively higher GAOs.     

The treatment of leachates from domestic wastes in landfills—I: Aerobic biological treatment of a medium-strength leachate

A medium-strength leachate from domestic solid wastes in a landfill (COD 5000 mg l⁻¹, BOD 3000 mg l⁻¹ was treated using aerobic biological processes in continuous-flow, laboratory-scale reactors at low temperatures. Each unit was completely mixed, and mixed liquor was wasted such that solids retention time (SRT) was equal to the hydraulic retention period.At 10 C with addition of phosphate (COD:P less than 100:1) SRT values of 10 days were required to obtained well-clarified effluents, and high removal of BOD (>;98%) and COD (>;92%). Reduction of temperature to 5°C resulted in adverse effects on settling of sludges from units with SRT values of less than 10 days, but in other units good removal of organic materials could still be obtained. These units operated successfully with concentrations of mixed liquor volatile suspended solids (MLVSS) of 1450 mg l⁻¹, equivalent to a ratio of F/M of 0.21 kg BOD kg⁻¹ MLVSS day⁻¹ or less. Removal of ammoniacal nitrogen which took place (influent concentration 80 mg l⁻¹ as N) resulted from incorporation in biomass, and at SRT values of 10 days no nitrification took place at 5 or 10 C. Higher concentrations of ammonia in influent leachates resulted in ammonia in effluents when the ratio of BOD:N was less than about 100:3.6. Increasing the SRT of units to 20 days resulted in erratic conversion to nitrite, but reduced pH-values and possible simultaneous denitrification caused floating sludges and poorly-clarified effluents. Removal of ammonia is identified as a major problem when treating leachates, and further research is recommended.     

Halophyte filter beds for treatment of saline wastewater from aquaculture

The expansion of aquaculture and the recent development of more intensive land-based marine farms require efficient and cost-effective systems for treatment of highly nutrient-rich saline wastewater. Constructed wetlands with halophytic plants offer the potential for waste-stream treatment combined with production of valuable secondary plant crops. Pilot wetland filter beds, constructed in triplicate and planted with the saltmarsh plant Salicornia europaea, were evaluated over 88 days under commercial operating conditions on a marine fish and shrimp farm. Nitrogen waste was primarily in the form of dissolved inorganic nitrogen (TDIN) and was removed by 98.2 ± 2.2% under ambient loadings of 109-383 μmol l⁻¹. There was a linear relationship between TDIN uptake and loading over the range of inputs tested. At peak loadings of up to 8185 ± 590 μmol l⁻¹ (equivalent to 600 mmol N m⁻² d⁻¹), the filter beds removed between 30 and 58% (250 mmol N m⁻² d⁻¹) of influent TDIN. Influent dissolved inorganic phosphorus levels ranged from 34 to 90 μmol l⁻¹, with 36-89% reduction under routine operations. Dissolved organic nitrogen (DON) loadings were lower (11-144 μmol l⁻¹), and between 23 and 69% of influent DON was removed during routine operation, with no significant removal of DON under high TDIN loading. Over the 88-day study, cumulative nitrogen removal was 1.28 mol m⁻², of which 1.09 mol m⁻² was retained in plant tissue, with plant uptake ranging from 2.4 to 27.0 mmol N g⁻¹ dry weight d⁻¹. The results demonstrate the effectiveness of N and P removal from wastewater from land-based intensive marine aquaculture farms by constructed wetlands planted with S. europaea.     

改善MSBR系统脱氮效果的试验研究

MSBR工艺是连续流与序操作 相结合的新型生物脱氮除磷技术,由于它的后置反硝化设计,碳源不足制约了系统的脱氮效果。为了改善这种状况,进行了将部分原水分流至缺氧区的试验。结果表明：引入原水后,缺氧区的反硝化速率常数提高了一倍,系统的反硝化速率和脱氮率相应提高。与此同时,分流造成了厌氧区的碳源不 足,加之厌氧区的回流增加,引入了较多的硝酸盐,使磷的释放和过量吸收受到影响,除磷效果下降。另外,针对中间沉淀区暴露出的运行和设计问题提出了一些改进措施。     

Incorporating microbial ecology into the metabolic modelling of polyphosphate accumulating organisms and glycogen accumulating organisms

In the enhanced biological phosphorus removal (EBPR) process, the competition between polyphosphate accumulating organisms (PAO) and glycogen accumulating organisms (GAO) has been studied intensively in recent years by both microbiologists and engineers, due to its important effects on phosphorus removal performance and efficiency. This study addresses the impact of microbial ecology on assessing the PAO-GAO competition through metabolic modelling, focussing on reviewing recent developments, discussion of how the results from molecular studies can impact the way we model the process, and offering perspectives for future research opportunities based on unanswered questions concerning PAO and GAO metabolism. Indeed, numerous findings that are seemingly contradictory could in fact be explained by the metabolic behaviour of different sub-groups of PAOs and/or GAOs exposed to different environmental and operational conditions. Some examples include the glycolysis pathway (i.e. Embden-Meyerhof-Parnas (EMP) vs. Entner-Doudoroff (ED)), denitrification capacity, anaerobic tricarboxylic acid (TCA) cycle activity and PAOs’ ability to adjust their metabolism to e.g. a GAO-like metabolism. Metabolic modelling may further yield far-reaching influences on practical applications as well, and serves as a bridge between molecular/biochemical research studies and the optimisation of wastewater treatment plant operation.     

污水强化除磷工艺的现状与未来

对强化生物除磷工艺的基本概念、外加碳源的作用、脱氮除磷的关系、环境影响参数进行了阐述,并介绍了聚磷菌菌群研究的最新进展。最后探讨了如何通过生产鸟粪石(MAP)实现磷元素回收,并围绕污水除磷和回收磷这一课题,提出了研究方向。     

Nitrous oxide generation in full-scale biological nutrient removal wastewater treatment plants

International guidance for estimating emissions of the greenhouse gas, nitrous oxide (N₂O), from biological nutrient removal (BNR) wastewater systems is presently inadequate. This study has adopted a rigorous mass balance approach to provide comprehensive N₂O emission and formation results from seven full-scale BNR wastewater treatment plants (WWTP). N₂O formation was shown to be always positive, yet highly variable across the seven plants. The calculated range of N₂O generation was 0.006-0.253 kgN₂O-N per kgN denitrified (average: 0.035 ± 0.027). This paper investigated the possible mechanisms of N₂O formation, rather than the locality of emissions. Higher N₂O generation was shown to generally correspond with higher nitrite concentrations, but with many competing and parallel nitrogen transformation reactions occurring, it was very difficult to clearly identify the predominant mechanism of N₂O production. The WWTPs designed and operated for low effluent TN (i.e. <10 mgN L⁻¹) had lower and less variable N₂O generation factors than plants that only achieved partial denitrification.