Development of a 2-sludge, 3-stage system for nitrogen and phosphorous removal from nutrient-rich wastewater using granular sludge and biofilms

A novel 2-sludge 3-stage process using a combination of granular sludge and biofilm was developed to achieve biological removal of nitrogen and phosphorus from nutrient-rich wastewater. The system consists of a granular sequencing batch reactor (SBR) working under alternating anaerobic/anoxic conditions supplemented with a short aerobic phase and an aerobic biofilm SBR. The wastewater is first fed to the granular SBR reactor, where easily biodegradable carbon sources are taken up primarily by polyphosphate accumulating organisms (PAOs). The supernatant resulting from quick settling of the granular sludge is then fed to the biofilm SBR for nitrification, which produces oxidized nitrogen that is returned to the granular reactor for simultaneous denitrification and phosphorus removal. While maximizing the utilization of organic substrates and reducing operational costs, as do other 2-sludge processes previously reported in literature, the proposed system solves the bottleneck problem of traditional 2-sludge systems, namely high effluent ammonia concentration, due to its high-volume exchange ratios. An ammonia oxidation rate of 32 mg N/Lh was achieved in the biofilm SBR, which produced nitrite as the final product. This nitrite stream was found to cause major inhibition on the anoxic P uptake and also to result in the accumulation of N(2)O. These problems were solved by feeding the nitrite-containing stream continuously to the granular reactor in the anoxic phase. With a nitrogen and phosphorus removal efficiency of 81% and 94%, respectively, the system produces an effluent that is suitable for land irrigation from a wastewater stream containing 270 mg N/L of total nitrogen and 40 mg P/L of total phosphorus.     

投加有效微生物强化SBR和SBBR除污效果的研究

将有效微生物（EM）富集培养液分别引入序批式反应器（SBR）和序批式生物膜反应器（SBBR）,构成新型的EM—SBR和EM—SBBR污水处理系统,以不接种EM的SBR和SBBR为对照,分别考察了各反应器的除污效果。结果表明,当EM在SBR中形成稳定的优势菌群后,可显著提高活性污泥的浓度,并可改善污泥的沉降性能;EM—SBR在曝气时间为4 h时对COD和NH4^＋-N的去除率均大于94%,EM—SBBR对COD和NH4^＋-N的去除率比对照组均高出7%左右;EM—SBR因菌种随出水流失造成除污效果下降而需要周期性投菌,EM—SBBR因附着性生物膜的存在有效减少了菌种的流失量,从而使其投菌周期较EM—SBR的大为延长,EM—SBBR除污效果周期性下降的主要原因为菌种退化。     

改良型SBR工艺对奶牛场废水中抗生素的去除效果

奶牛场废水中的有机物和抗生素对其还田利用不利,为此,采用带缺氧区的推流式SBR(简称改良型SBR)工艺处理干清粪条件下间歇产生的奶牛场废水,重点考察其对抗生素的去除效果。结果表明,当进水COD、NH4+-N、TN、TP浓度分别为1 234~4 696、768~1 365、880~1 370、5.62~12.02 mg/L时,经改良型SBR工艺处理后,出水COD可降至401~544 mg/L、NH4+-N始终低于10mg/L,TN平均损失率为22.38%,TP基本没有被去除。奶牛场废水中磺胺类和β-内酰胺类抗生素总浓度为3.84~4.48μg/L,改良型SBR工艺对其总去除率可达到72.97%~90.82%,且对10种较高浓度的磺胺类抗生素(每种添加浓度均为50μg/L,共计500μg/L)也有很好的去除效果,去除率可达95.75%~95.97%。生物降解是奶牛场废水中磺胺类和β-内酰胺类抗生素的主要去除途径,另外,磺胺类抗生素的去除与其分子结构中S—N键的断裂有重要关系。在不影响COD去除效果的条件下,调整反应器的混合液回流量或进水量均可减少碱度投加量,从而降低运行成本。     

The effect of heavy metals on nitrogen and oxygen demand removal in constructed wetlands

The objective of this study is to investigate the respective effects of Zn, Pb and Cd as well as the combined effect of Zn, Pb, Cd and Cu on the removal of nitrogen and oxygen demand in constructed wetlands. Four laboratory-scale gravel-filled subsurface-flow constructed wetland units planted with cattails (Typha latifolia) were operated outdoors and fed with primary-treated domestic wastewater at a constant flow rate of 25 ml/min. After 6 months, three of the wetland units were fed with the same type of wastewater spiked with Zn(II), Pb(II) and Cd(II), respectively, at 20, 5 and 1 mg/l for a further 9 months. The remaining unit was fed with the same type of wastewater spiked with a combination of Zn(II), Pb(II), Cd(II) and Cu(II) at concentrations of 10, 2.5, 0.5 and 5 mg/l, respectively, over the same period. The chemical oxygen demand (COD) and ammoniacal nitrogen (AN) concentrations were monitored at the inlet, outlet and three additional locations along the length of the wetland units to assess the performance of the wetland units at various metal loadings. At the end of the study, all cattail plants were harvested for the determination of total Kjeldahl nitrogen and metal concentrations. The results showed that the COD removal efficiency was practically independent of increasing metal loading or a combination of metal loadings during the duration of the study. In contrast, the AN removal efficiency deteriorated progressively with increasing metal loading. The relative effect of the heavy metals was found to increase in the order: Zn相似文献   

Removal of veterinary antibiotics from sequencing batch reactor (SBR) pretreated swine wastewater by Fenton's reagent

The large-scale application of veterinary antibiotics in livestock industry makes swine wastewater an important source of antibiotics pollution. This work investigated the degradation of six selected antibiotics, including five sulfonamides and one macrolide, by Fenton's reagent in swine wastewater pretreated with sequencing batch reactor (SBR). The dosing mode and practical dosage of Fenton's reagent were optimized to achieve an effective removal of antibiotics while save the treatment cost. The effects of initial pH, chemical oxygen demand (COD) and suspended solids (SS) of the SBR effluent on antibiotics degradation were examined. The results indicate that the optimal conditions for Fenton's reagent with respect to practical application were as follows: batch dosing mode, 1.5:1 molar ratio of [H₂O₂]/[Fe²⁺], initial pH 5.0. Under the optimal conditions, Fenton's reagent could effectively degrade all the selected antibiotics and was resistant to the variations in the background COD (0-419 mg/L) and SS (0-250 mg/L) of the SBR effluent. Besides, Fenton's reagent helped to not only remove total organic carbon (TOC), heavy metals (As, Cu and Pb) and total phosphorus (TP), but also inactivate bacteria and reduce wastewater toxicity. This work demonstrates that the integrated process combining SBR with Fenton's reagent could provide comprehensive treatment to swine wastewater.     

Comparisons of low-cost adsorbents for treating wastewaters laden with heavy metals

In this article, the removal performance and cost-effectiveness of various low-cost adsorbents derived from agricultural waste, industrial by-product or natural material are evaluated and compared to those of activated carbon for the removal of heavy metals (Cd(II), Cr(III), Cr(VI), Cu(II), Ni(II) and Zn(II)) from metals-contaminated wastewater. To highlight their technical applicability, selected information on pH, dose required, initial metal concentration, adsorption capacity and the price of the adsorbents is presented. It is evident from the survey of 102 published studies (1984-2005) that low cost adsorbents derived from agricultural waste have demonstrated outstanding capabilities for the removal of heavy metal (Cr(VI): 170 mg/g of hazelnut shell activated carbon, Ni(II): 158 mg/g of orange peel, Cu(II): 154.9 mg/g of soybean hull treated with NaOH and citric acid, Cd(II): 52.08 mg/g of jackfruit), compared to activated carbon (Cd(II): 146 mg/g, Cr(VI): 145 mg/g, Cr(III): 30 mg/g, Zn(II): 20 mg/g). Therefore, low-cost adsorbents can be viable alternatives to activated carbon for the treatment of metals-contaminated wastewater. It is important to note that the adsorption capacities presented in this paper vary, depending on the characteristics of the individual adsorbent, the extent of surface modification and the initial concentration of the adsorbate. In general, technical applicability and cost-effectiveness are the key factors that play major roles in the selection of the most suitable adsorbent to treat inorganic effluent.     

固定化氨氧化菌短程硝化的启动研究

采用亲水性玻璃态单体,应用辐射技术制备生物相容性高分子共聚物载体,使用固定化细胞增殖技术对氨氧化菌进行固定化,并以流化床为生物反应器,采用SBR运行方式对人工配水进行短程硝化的启动研究.结果表明:当进水氨氮浓度为100、75、50和25mg/L时,对氨氮的的去除率分别为98.6%、99.1%、98.8%和99.8% ,亚硝化率分别为 98.6%、94,5%、95.2%和94.7%:对氨氮的去除速率由开始时的10.6mg/(L·d)提高到25.7mg/(L·d),耗氧速率(OUR)则由0.37mg/(L·d)提高到1.12mg/(L·d).可见,该方法具有启动速度快、亚硝化程度高、容易控制等优点.     

Bioaugmentation of a sequencing batch reactor with <Emphasis Type="Italic">Archaea</Emphasis> for the treatment of reject water

In this study, the bioaugmentation of a sequencing batch reactor (SBR) for the treatment of reject water from wastewater treatment plant was evaluated. For the bioaugmentation step a product containing an enrichment of microorganisms from the Archaea domain was used to enhance the performance of the reactor for treating reject water. The experiment was carried out in two parallel lab-scale sequencing batch reactors. The first one (SBR A) was bioaugmented with a suspension of microorganisms from the Archaea domain, while the second reactor (SBR B) was not bioaugmented. The results here presented show that the SBR technology could sustain efficient NH ₄ ⁺ –N and chemical oxyden demand removal rates and can be applied for the treatment of reject water. Moreover, the addition of microorganisms belonging to the Archaea domain improved the SBR overall operation, especially when the loading in the influent was increased. Administering Archaea to the reactor had also a positive effect on ammonia oxidation as well as on the nitrite removal.     

微电解/SBR工艺处理皮革生产废水的试验研究

采用微电解/SBR工艺处理晋江某皮革厂生产废水.结果表明,酸性条件下微电解法对皮革废水中COD的去除效果优于碱性条件下的,且铸铁/活性炭填料对COD的去除效果优于铸铁、纯铁、纯铁/活性炭的.当Fe~(2+)的浓度为3 mg/L时已能满足SBR池中微生物对铁的需求,过多投加铁无助于微生物对COD的去除.微电解/SBR工艺可对皮革废水进行有效处理,除氨氮外的各项出水指标均达到<污水综合排放标准>(GB 8978——1996)的二级标准,且微电解填料为工业废料,可达到以废治废的目的.     

应用SBR实现有机废水厌氧氨氧化生物脱氮的研究

采用SBR反应器,以硝化污泥和厌氧氨氧化(ANAMMOX)颗粒污泥的混合污泥为接种污泥,以有机模拟废水为研究对象,进行了厌氧氨氧化生物脱氮工艺研究。结果表明,在控制温度为25℃,水力停留时间为12 d,pH值为7.2～8.5,进水NH4+-N为220 mg/L左右、NO2--N为138 mg/L左右、COD为294 mg/L的条件下成功启动了SBR反应器。在高氨氮、低有机物浓度的条件下,ANAMMOX菌和异养反硝化菌能够实现共存,且ANAMMOX菌仍能成为优势菌属,AN-AMMOX反应是反应器中的主导反应。镜检发现,优势菌尺寸约为1μm,呈圆形或椭圆形,成簇聚生,表面可观察到明显的漏斗状缺口,具有典型的厌氧氨氧化菌特征。污泥中形成了以厌氧氨氧化球状菌为主、其他杆状菌和丝状菌共存的微生物混培体。     

Biomass characteristics in three sequencing batch reactors treating a wastewater containing synthetic organic chemicals

The physical and biochemical characteristics of the biomass in three lab-scale sequencing batch reactors (SBR) treating a synthetic wastewater at a 20-day target solids retention time (SRT) were investigated. The synthetic wastewater feed contained biogenic compounds and 22 organic priming compounds, chosen to represent a wide variety of chemical structures with different N, P and S functional groups. At a two-day hydraulic retention time (HRT), the oxidation-reduction potential (ORP) cycled between -100 (anoxic) and 100 mV (aerobic) in the anoxic/aerobic SBR, while it remained in a range of 126+/-18 and 249+/-18 mV in the aerobic sequencing batch biofilm reactor (SBBR) and the aerobic SBR reactor, respectively. A granular activated sludge with excellent settleability (SVI=98+/-31 L mg(-1)) developed only in the anoxic/aerobic SBR, compared to a bulky sludge with poor settling characteristics in the aerobic SBR and SBBR. While all reactors had very good COD removal (>90%) and displayed nitrification, substantial nitrogen removal (74%) was only achieved in the anoxic/aerobic SBR. During the entire operational period, benzoate, theophylline and 4-chlorophenol were completely removed in all reactors. In contrast, effluent 3-nitrobenzoate was recorded when its influent concentration was increased to 5 mg L(-1) and dropped only to below 1 mg L(-1) after 300 days of operation. The competent (active) biomass fractions for these compounds were between 0.04% and 5.52% of the total biomass inferred from substrate-specific microbial enumerations. The measured competent biomass fractions for 4-chlorophenol and 3-nitrobenzoate degradation were significantly lower than the influent COD fractions of these compounds. Correspondent to the highest competent biomass fraction for benzoate degradation among the test SOCs, benzoate oxidation could be quantified with an extant respirometric technique, with the highest specific oxygen uptake rate (SOUR(benzoate), 0.026 g O2 h(-1) g(-1) XCOD) in the anoxic/aerobic SBR. These combined results suggest that operating SBRs with alternative anoxic/aerobic cycles might facilitate the formation of granular sludge with good settleability, and retain comparable removal of nitrogen and synthetic organic compounds. Hence, the practice of anoxic/aerobic cycling should be considered in wastewater treatment systems whenever possible.     

Biodegradation of agricultural herbicides in sequencing batch reactors under aerobic or anaerobic conditions

This study investigated the biodegradability of the herbicides isoproturon and 2,4-dichlorophenoxyacetic acid (2,4-D) in sequencing batch reactors (SBRs). Two laboratory-scale (2L liquid volume) SBRs were employed: one reactor performing under aerobic and the other under anaerobic conditions. The aerobic SBR was operated at an ambient temperature (22+/-2 degrees C), while the anaerobic SBR was run in the lower mesophilic range (30+/-2 degrees C). Each bioreactor was seeded with a 3:1 mixture (by weight) of fresh sludge and biomass that had been previously exposed to both herbicides. The effect of herbicide concentration on either treatment process was explored at a hydraulic retention time (HRT) of 48 h, using glucose as a supplemental carbon substrate. Although no isoproturon degradation was observed in either system during the study, complete 2,4-D removal occurred after an acclimation period of approximately 30 d (aerobic SBR) and 70 d (anaerobic SBR). The aerobic reactor achieved complete 2,4-D utilization at feed concentrations up to 500 mg/L. A further increase to 700 mg/L, however, proved to be inhibitory since 2,4-D biodegradation was negligible. On the other hand, the anaerobic SBR was able to degrade 120 mg/L of 2,4-D, which corresponds to 40% of the maximum feed concentration applied. Moreover, glucose was consumed first throughout the experiment in a sequential utilization pattern relating to 2,4-D, with biodegradation of both substrates following closely first-order kinetics.     

粉末炭/SBR工艺处理高浓豆制品废水研究

对粉末炭(PAC)/SBR工艺处理高浓度豆制品生产废水进行了研究,探讨了PAC用量、曝气时间、曝气方式对处理效果的影响.结果表明:在PAC用量为400 mg/L、PAC/SBR反应器进水COD负荷<6 000 mg/L及限制曝气时间为6h时,最终出水的COD和NH 4-N浓度均能达标.COD由2850 mg/L降至611mg/L时,反应符合零级反应动力学规律;COD<611 mg/L时,反应符合一级反应动力学规律.     

固定化微生物抗Cr~(6+)毒性能力及其去除特性研究

采用固定化微生物SBR反应器和普通活性污泥SBR反应器处理投加了Cr^6＋的生活污水,考察了固定化微生物去除COD及Cr^6＋的能力及抗毒性,并对除铬机理作了初步探讨。结果表明：在保证对COD的去除率较稳定的条件下,固定化微生物与普通活性污泥所能承受的Cr^6＋浓度分别为70mg／L和1．9mg／L;污泥对Cr^6＋有很强的吸附及还原能力,反应器中的Cr^6＋最终主要以Cr^3＋的形式通过排放剩余污泥而被去除;在进水Cr^6＋浓度〈70mg／L时,两个反应器中的微生物对铬的吸附基本符合Langmuir吸附等温式,这种吸附作用和微生物的量有关。而和微生物活性的关系不大。该方法为重金属废水的生物处理开辟了新思路。     

Toxicity of fluoride to microorganisms in biological wastewater treatment systems

Fluoride is a common contaminant in a variety of industrial wastewaters. Available information on the potential toxicity of fluoride to microorganisms implicated in biological wastewater treatment is very limited. The objective of this study was to evaluate the inhibitory effect of fluoride towards the main microbial populations responsible for the removal of organic constituents and nutrients in wastewater treatment processes. The results of short-term batch bioassays indicated that the toxicity of sodium fluoride varied widely depending on the microbial population. Anaerobic microorganisms involved in various metabolic steps of anaerobic digestion processes were found to be very sensitive to the presence of fluoride. The concentrations of fluoride causing 50% metabolic inhibition (IC₅₀) of propionate- and butyrate-degrading microorganisms as well as mesophilic and thermophilic acetate-utilizing methanogens ranged from 18 to 43 mg/L. Fluoride was also inhibitory to nitrification, albeit at relatively high levels (IC₅₀ = 149 mg/L). Nitrifying bacteria appeared to adapt rapidly to fluoride, and a near complete recovery of their metabolic activity was observed after only 4 d of exposure to high fluoride levels (up to 500 mg/L). All other microbial populations evaluated in this study, i.e., glucose fermenters, aerobic glucose-degrading heterotrophs, denitrifying bacteria, and H₂-utilizing methanogens, tolerated fluoride at very high concentrations (>500 mg/L).     

好氧颗粒污泥发生丝状菌污泥膨胀的控制措施

在SBR反应器内接种好氧颗粒污泥,经驯化后对人工模拟废水的处理效果良好。考察了培养过程中污泥形态的变化以及发生丝状菌污泥膨胀时反应器对污染物的去除效果,并探讨了丝状菌在污泥颗粒化过程中的作用以及控制丝状菌污泥膨胀的方法。结果表明,丝状菌污泥膨胀对COD的去除率有影响,但对去除NH3-N、TP的效果影响不大。通过增加反应器内的水力剪切力对控制丝状菌污泥膨胀有一定的效果,而减小C/N值,均衡进水中的营养可从根本上解决污泥膨胀问题。成熟的好氧颗粒污泥的MLSS约为3 000 mg/L,沉降性能较好,SVI为77 mL/g;对COD、NH3-N、TP均具有较高的去除率,分别达到94.52%9、5%9、0%左右。     

Occurrence and treatment of wastewater-derived organic nitrogen

Dissolved organic nitrogen (DON) derived from wastewater effluent can participate in reactions that lead to formation of nitrogenous chlorination by-products, membrane fouling, eutrophication, and nitrification issues, so management of DON is important for both wastewater reuse applications and nutrient-sensitive watersheds that receive discharges from treated wastewater. This study documents DON occurrence in full-scale water/wastewater (W/WW) treatment plant effluents and assesses the removal of wastewater-derived DON by several processes (biodegradation, coagulation, softening, and powdered activated carbon [PAC] adsorption) used for advanced treatment in wastewater reuse applications. After varying levels of wastewater treatment, the dominant aqueous nitrogenous species shifts from ammonia to nitrate after aerobic processes and nitrate to DON in tertiary treatment effluents. The fraction of DON in total dissolved nitrogen (TDN) accounts for at most 52% in tertiary treated effluents (median = 13%) and 54% in surface waters impacted by upstream wastewater discharges (median = 31%). The 5-day biodegradability/bioavailability of DON (39%) was higher, on average, than that of dissolved organic carbon (DOC, 26%); however, upon chlorination, the DON removal (3%) decreased significantly. Alum coagulation (with ≥8 mg/L alum per mg/L DOC) and lime softening (with pH 11.3-11.5) removed <25% of DON and DOC without selectivity. PAC adsorption preferentially removed more DOC than DON by 10% on average. The results provided herein hence shed light on approaches for reducing organic nitrogen content in treated wastewater.     

Enhanced chitosan beads-supported Fe-nanoparticles for removal of heavy metals from electroplating wastewater in permeable reactive barriers

The removal of heavy metals from electroplating wastewater is a matter of paramount importance due to their high toxicity causing major environmental pollution problems. Nanoscale zero-valent iron (NZVI) became more effective to remove heavy metals from electroplating wastewater when enhanced chitosan (CS) beads were introduced as a support material in permeable reactive barriers (PRBs). The removal rate of Cr (VI) decreased with an increase of pH and initial Cr (VI) concentration. However, the removal rates of Cu (II), Cd (II) and Pb (II) increased with an increase of pH while decreased with an increase of their initial concentrations. The initial concentrations of heavy metals showed an effect on their removal sequence. Scanning electron microscope images showed that CS-NZVI beads enhanced by ethylene glycol diglycidyl ether (EGDE) had a loose and porous surface with a nucleus-shell structure. The pore size of the nucleus ranged from 19.2 to 138.6 μm with an average aperture size of around 58.6 μm. The shell showed a tube structure and electroplating wastewaters may reach NZVI through these tubes. X-ray photoelectron spectroscope (XPS) demonstrated that the reduction of Cr (VI) to Cr (III) was complete in less than 2 h. Cu (II) and Pb (II) were removed via predominant reduction and auxiliary adsorption. However, main adsorption and auxiliary reduction worked for the removal of Cd (II). The removal rate of total Cr, Cu (II), Cd (II) and Pb (II) from actual electroplating wastewater was 89.4%, 98.9%, 94.9% and 99.4%, respectively. The findings revealed that EGDE-CS-NZVI-beads PRBs had the capacity to remediate actual electroplating wastewater and may become an effective and promising technology for in situ remediation of heavy metals.     

Effect of extended idle conditions on structure and activity of granular activated sludge

In industry and in tourist areas, periods exist during which no or only very little sewage is produced, and the wastewater treatment facilities have to be set into an idle phase over several days and even weeks. When wastewater is generated again and delivered to the treatment plant, the microorganisms in the activated sludge plant may have lost activity, and the activated sludge flocs may have disintegrated. From previous observation, it is assumed that granular activated sludge is more resistant against long-term storage than activated sludge flocs. Experiments using a laboratory-scale sequencing batch reactor (SBR) were conducted to study the impacts of a 7-weeks anaerobic idle time on structural integrity and metabolic activity of granular activated sludge, and the time required to regain the former operational status of the plant. Oxygen consumption rate (OCR) was used as an indicator to evaluate the metabolic activity of the sludge. The results revealed that the size, color and sedimentation characteristics of the granular sludge did hardly change during the storage period. Sludge activity, however, dropped to values as low as 0.17 mg min(-1)L(-1). After restarting the reactor, the OCR increased within 1 day to a level of 0.57 mg min(-1)L(-1), kept rising at a linear rate in the following days, and reached after 1 week, a value of 5.74 mg min(-1)L(-1) typical for the former activity status. These results imply that granular activated sludge can be stored for a considerably long period of time, and brought into service again relatively quickly. After an idle period of 7 weeks, it took less than a week to regain full capacity of the SBR.     

两种序批式生物系统处理屠宰废水的对比试验

在相同的运行条件下,考察了序批式活性污泥系统和生物膜系统对屠宰废水的处理效果.试验结果表明,两种方法都是可行的,但生物膜系统的处理效果优于括性污泥系统,达到相同污染物去除率时,生物膜系统的运行管理更方便,且克服了活性污泥系统存在的一些问题.