Treatment of heavy metal-polluted wastewaters using the biofilms of a multistage rotating biological contactor

The ability of the biofilms of a three-stage rotating biological contactor (RBC) to treat wastewater contaminated with cadmium, copper and zinc was investigated. The system successfully removed the metals, in the order Cu > Zn > Cd with removal capacities of approximately 73, 42 and 33% respectively. Analysis of the contribution of each reactor indicated that metal removal was not uniform, with Reactor 1 showing a much higher removal capacity than Reactors 2 and 3. Energy dispersive X-ray spectroscopy (EDS) revealed the presence of all three metals on the surface of the biofilms in all three reactors. Closer inspection of the biofilms, in terms of biomass and biofilm thickness, revealed that the low metal removal in Reactors 2 and 3 was probably attributable to poor biofilm development in these two reactors compared to that in Reactor 1. The poor biofilm development was substantiated by low chemical oxygen demand (COD) removal in the latter two reactors.     

Biofilm reactors: an experimental and modeling study of wastewater denitrification in fluidized-bed reactors of activated carbon particles

A fluidized-bed biofilm reactor using activated carbon particles of 1.69 mm diameter as the support for biomass growth and molasses as the carbon source is used for wastewater denitrification.The start-up of the reactor was successfully achieved in 1 week by using a liquor from garden soil leaching as the inoculum and a superficial velocity u(0) = 5u(mf). Typical biofilm thickness is 800 mum; therefore covered activated carbon particles have 3.3 mm in diameter.Reactor hydrodynamics was studied by tracer (KCl solution) experiments. The analysis based on residence time distribution theory involved a model with axial dispersion flow and tracer diffusion with linear adsorption inside the biofilm. Peclet numbers higher than 100 were found, allowing the plug flow assumption for the reactor model.Experimental profiles of nitrate and nitrite species were explained by a kinetic model of two consecutive zero-order reactions coupled with substrate diffusion inside the biofilm. Under the operating conditons used thick biofilms were obtained working in a diffusion-controlled regime.Comparison is made with results obtained in the same reactor with sand particles as the support for biomass growth. Activated carbon as the support has the following advantages: good adsorptive characteristics, homogeneous biofilm thickness along the reactor, and easy restart-up of the reactor. (c) 1992 John Wiley & Sons, Inc.     

生物膜法和SBR法相结合处理难降解制药废水的研究

采用生物膜法和SBR法相结合的废水处理工艺处理含抗生素类等难降解的制药废水 ,对生物膜的耐冲击负荷能力、生物膜对进水可生化性的影响、生物膜对好氧SBR活性污泥性能的影响、pH对系统去除效果的影响等工艺条件进行研究 ,并通过与传统SBR处理工艺的对比试验 ,进一步揭示了生物膜法和SBR法相结合的处理工艺强的耐冲击负荷能力。     

Impact of membrane solid-liquid separation on design of biological nutrient removal activated sludge systems

Installing membranes for solid-liquid separation into biological nutrient removal (BNR) activated sludge (AS) systems makes a profound difference not only in the design of the BNR system itself, but also in the design approach for the whole wastewater treatment plant (WWTP). In multizone BNR systems with membranes in the aerobic reactor and fixed volumes for the anaerobic, anoxic, and aerobic zones (i.e., fixed volume fractions), the mass fractions can be controlled (within a range) with the interreactor recycle ratios. This zone mass fraction flexibility is a significant advantage in membrane BNR systems over conventional BNR systems with SSTs, because it allows for changing of the mass fractions to optimize biological N and P removal in conformity with influent wastewater characteristics and the effluent N and P concentrations required. For PWWF/ADWF ratios in the upper range (f(q) approximately 2.0), aerobic mass fractions in the lower range (f(maer) < 0.60), and high (usually raw) wastewater strengths, the indicated mode of operation of MBR BNR systems is as extended aeration WWTPs. Although the volume reduction compared with equivalent conventional BNR systems with secondary settling tanks is not as large (40% to 60%), the cost of the membranes can be offset against sludge thickening and stabilization costs. Moving from a flow-unbalanced raw wastewater system to a flow-balanced (f(q) = 1), low (usually settled) wastewater strength system can double the ADWF capacity of the biological reactor, but the design approach of the WWTP changes from extended aeration to include primary sludge stabilization. The cost of primary sludge treatment then has to be paid from the savings from the increased WWTP capacity.     

生物膜型污水脱氮系统中膜结构及微生物生态研究进展

生物膜法污水脱氮系统主要利用生物膜中脱氮功能微生物的代谢活动去除氮素,从而达到净化水质的目的,研究脱氮生物膜的微观结构和微生物生态是揭示生物膜脱氮机理从而提高脱氮效率的重要途径.本文综述了生物膜型污水脱氮系统类型、生物膜微观结构特征及其影响因素、生物膜型污水脱氮系统内氮素传质过程、脱氮机理和生物膜数学模型等方面的研究进展.另外,本文介绍了生物膜型污水脱氮系统内生物膜脱氮功能微生物分布特征,不同生物膜脱氮系统、底物、运行条件和时间对功能微生物群落影响,及新型脱氮功能微生物等方面的研究进展,为生物膜脱氮技术的深入研究提供参考.     

Biological nitrogen removal using a vertically moving biofilm system

In this study, a biological nitrogen removal process using a vertically moving biofilm system was used to treat synthetic wastewater. The process consisted of two pre-denitrification units, one combined carbonaceous removal/nitrification unit and three nitrification units. Each unit employed biofilm growth on a plastic module. In the anoxic units, the modules were vertically moved, while always submerged, in the bulk fluid; in the aerobic units, they were moved vertically up into the air and down into the wastewater. Three small-scale experiments, having different recirculation ratios and influent loadings, were conducted at a controlled temperature of 11 degrees C. In this system, the carbonaceous removal efficiency was in the range of 94-96% and the total nitrogen removal efficiency was 77-82%. In the anoxic units, the denitrification efficiency was 94-98% and the areal denitrification rates, based on the surface area of the biofilm modules, were 2.9-3.8 g NO3-N/(m2 x d). The nitrification efficiency occurring in the aerobic tanks was up to 95% and the maximum areal ammonium removal rates were 1.3-1.8 g NH4-N/(m2 x d).     

基于好氧反硝化及反硝化聚磷菌强化的低温低碳氮比生活污水生物处理中试研究

【背景】低碳氮比生活污水很难达标处理,多级A/O工艺、生物强化技术及生物膜技术的有机结合可有效解决这一问题。【目的】开发出一种泥膜共生多级A/O工艺并进行中试研究,驯化出高效脱氮除磷菌剂并对系统进行生物强化。【方法】通过测定中试设备出水及污水处理厂出水化学需氧量(Chemical oxygen demand,COD)、氨氮(NH_4~+-N)、硝氮(NO_3~--N)、总氮(Total nitrogen,TN)、总磷(Total phosphorus,TP)对比分析两种工艺的污染物去除效能,利用高通量测序技术对比生物强化技术对系统微生物群落结构的影响。【结果】中试设备对COD、NH_4~+-N、NO_3~--N、TN、TP的去除效果均优于污水处理厂的处理工艺;驯化的低温好氧反硝化菌TN去除率最大值可达84.21%,驯化的低温反硝化聚磷菌群对磷的去除率最高可达85.75%;利用驯化菌群对中试设备进行生物强化后较好地改善了系统NH_4~+-N、NO_3~--N、TN、TP的去除效果;经生物强化后,具有好氧反硝化和反硝化聚磷功能的Pseudomonas菌群明显增多。【结论】泥膜共生多级A/O工艺对于低碳氮比生活污水的处理具有很好的效果,利用生物强化技术可有效提高低温条件下系统污染物去除效能。     

Development of a simultaneous partial nitrification and anaerobic ammonia oxidation process in a single reactor

Up-flow oxygen-controlled biofilm reactors equipped with a non-woven fabric support were used as a single reactor system for autotrophic nitrogen removal based on a combined partial nitrification and anaerobic ammonium oxidation (anammox) reaction. The up-flow biofilm reactors were initiated as either a partial nitrifying reactor or an anammox reactor, respectively, and simultaneous partial nitrification and anammox was established by careful control of the aeration rate. The combined partial nitrification and anammox reaction was successfully developed in both biofilm reactors without additional biomass inoculation. The reactor initiated as the anammox reactor gave a slightly higher and more stable mean nitrogen removal rate of 0.35 (± 0.19) kg-N m⁻³ d⁻¹ than the reactor initiated as the partial nitrifying reactor (0.23 (± 0.16) kg-N m⁻³ d⁻¹). FISH analysis revealed that the biofilm in the reactor started as the anammox reactor were composed of anammox bacteria located in inner anoxic layers that were surrounded by surface aerobic AOB layers, whereas AOB and anammox bacteria were mixed without a distinguishable niche in the biofilm in the reactor started as the partial nitrifying reactor. However, it was difficult to efficiently maintain the stable partial nitrification owing to inefficient aeration in the reactor, which is a key to development of the combined partial nitrification and anammox reaction in a single biofilm reactor.     

焦化废水工业处理装置和实验室装置硝化菌群的分子比较

反应器的群落结构分析有助于对工业装置的故障原因进行诊断。为了解决某焦化废水处理装置硝化功能低下的故障,构建了一套相似的实验室装置作为参照系统,该装置的硝化功能良好。通过工业装置和实验室装置好氧池生物膜16SrDNA克隆文库的比较,分析了它们之间硝化菌群的组成差异。实验室装置克隆文库的构成说明Nitrosomonas europaea-Nitrosoccus mobilis类群和Nitrospira属Ⅰ亚区系分别是该工艺条件下优势的氨氧化菌和亚硝酸氧化菌,但工业装置的克隆文库中却没有找到任何与硝化菌序列相近的克隆,这说明工业装置中硝化菌的多度较低。进一步使用Taqman荧光探针实时定量PCR测定了样品中Nitrospira属的多度,实验室装置中Nitrospira属16S rDNA的拷贝数达到3.4×106个/微克基因组DNA,而工业装置的测定值不到实验室装置的1/300。这些试验结果都表明工业装置好氧池微生物群落中缺少适当的硝化菌群是造成其硝化能力低下的重要原因。提高菌群中Nitrosomonas属和Nitrospira属的多度是解决工业装置硝化能力低下的关键。     

Algae-based biofilm productivity utilizing dairy wastewater: effects of temperature and organic carbon concentration

Background

Biofilm-based microalgal growth was determined as functions of organic chemical loading and water temperature utilizing dairy wastewater from a full-scale dairy farm. The dairy industry is a significant source of wastewater worldwide that could provide an inexpensive and nutrient rich feedstock for the cultivation of algae biomass for use in downstream processing of animal feed and aquaculture applications. Algal biomass was cultivated using a Rotating Algal Biofilm Reactor (RABR) system. The RABR is a biofilm-based technology that has been designed and used to remediate municipal wastewater and was applied to treat dairy wastewater through nutrient uptake, and simultaneously provide biomass for the production of renewable bioproducts.

Results

Aerial algal biofilm growth rates in dairy wastewater at 7 and 27 °C temperatures were shown to be 4.55?±?0.17 g/m²-day and 7.57?±?1.12 g/m²-day ash free dry weight (AFDW), respectively. Analysis of Variance (ANOVA) calculations indicated that both an increase in temperature of the wastewater and an increase in the level of organic carbon, from 300 to 1200 mg L^-1, contributed significantly to an increase in the rate of biomass growth in the system. However, ANOVA results indicated that the interaction of temperature and organic carbon content was not significantly related to the biofilm-based growth rate.

Conclusion

A microalgae-based biofilm reactor was successfully used to treat turbid dairy wastewater. Temperature and organic carbon concentration had a statistically significant effect on algae-based biofilm productivity and treatment of dairy wastewater. The relationships between temperature, TOC, and productivity developed in this study may be used in the design and assessment of wastewater remediation systems and biomass production systems utilizing algae-based biofilm reactors for treating dairy wastes.

     

Experimental investigation of the external nitrification biological nutrient removal activated sludge (ENBNRAS) system

A systematic lab-scale experimental investigation is reported for the external nitrification (EN) biological nutrient removal (BNR) activated sludge (ENBNRAS) system, which is a combined fixed and suspended medium system. The ENBNRAS system was proposed to intensify the treatment capacity of BNR-activated sludge (BNRAS) systems by addressing two difficulties often encountered in practice: (a) the long sludge age for nitrification requirement; and (b) sludge bulking. In the ENBNRAS system, nitrification is transferred from the aerobic reactor in the suspended medium activated sludge system to a fixed medium nitrification system. Thus, the sludge age of the suspended medium activated sludge system can be reduced from 20 to 25 days to 8 to 10 days, resulting in a decrease in reactor volume per ML wastewater treated of about 30%. Furthermore, the aerobic mass fraction can also be reduced from 50% to 60% to <30% and concommitantly the anoxic mass fraction can be increased from 25% to 35% to >55% (if the anaerobic mass fraction is 15%), and thus complete denitrification in the anoxic reactors becomes possible. Research indicates that both the short sludge age and complete denitrification could ameliorate anoxic aerobic (AA) or low food/microorganism (F/M) ratio filamentous bulking, and hence reduce the surface area of secondary settling tanks or increase the treatment capacity of existing systems. The lab-scale experimental investigations indicate that the ENBNRAS system can obtain: (i) very good chemical oxygen demand (COD) removal, even with an aerobic mass fraction as low as 20%; (ii) high nitrogen removal, even for a wastewater with a high total kjeldahl nitrogen (TKN)/COD ratio, up to 0.14; (iii) adequate settling sludge (diluted sludge volume index [DSVI] <100 mL/g); and (iv) a significant reduction in oxygen demand.     

Color removal of real textile wastewater by sequential anaerobic and aerobic reactors

Textile wastewater from the Pusan Dyeing Industrial Complex (PDIC) was treated utilizing a two-stage continuous system, composed of an upflow anaerobic sludge blanket reactor and an activated sludge reactor. The effects of color and organic loading rates were studied by varying the hydraulic retention time and influent glucose concentration. The maximum color load to satisfy the legal discharge limit of color intensity in Korea (400 ADMI, unit of the American Dye Manufacturers Institute) was estimated to be 2,700 ADMI·L⁻¹ day⁻¹. This study indicates that the two-stage anaerobic/aerobic reaction system is potentially useful in the treatment of textile wastewater.     

Evaluation of biological nutrient removal from wastewater by Twin Circulating Fluidized Bed Bioreactor (TCFBBR) using a predictive fluidization model and AQUIFAS APP

A two-phase and three-phase predictive fluidization model based on the characteristics of a system such as media type and size, flow rates, and reactor cross sectional area was proposed to calculate bed expansion, solid, liquid and gas hold up and specific surface area (SSA) of the biofilm particles. The model was subsequently linked to 1d AQUIFAS APP software (Aquaregen) to model biological nutrient removal in two phase (anoxic) and three phase (aerobic) fluidized bed bioreactors. The credibility of the proposed model for biological nutrient removal was investigated using the experimental data from a Twin Circulating Fluidized Bed Bioreactors (TCFBBR) treating synthetic and municipal wastewater.The SSA of bio-particles and volume of the expanded bed were simulated as a function of operational parameters. Two-sided t-tests demonstrated that simulated SCOD, NH₄-N, NO₃-N, TN, VSS and biomass yields agreed with the experimental values at the 95% confidence level.     

Biodegradation of tetracycline antibiotics in A/O moving-bed biofilm reactor systems

Bioprocess and Biosystems Engineering - An anaerobic/aerobic moving-bed biofilm (A/O-MBBR) reactor system was constructed, and the treatment efficiency of aqueous antibiotics in wastewater was...     

Properties of a new strain of Nitrosomonas isolated from an aerobic biofilm in a domestic sewage-treatment system

A new ammonia-oxidizing strain, isolated from an aerobic biofilm in a domestic sewage-treatment system, was identified as a species of Nitrosomonas different from Nitrosomonas europaea. This strain had morphological features and growth characteristics typical of members of the genus Nitrosomonas. The G+C content of the DNA of this strain was 48.5 mol%, being lower than that of known strains of N. europaea. The extent of the homology between the DNA of this strain and that of other strains of N. europaea was less than 30%. After cells of this isolate, immobilized in a polyacrylamide gel, had been added to the aerobic reactor of a laboratory-scale sewage-treatment system, the concentration of ammonium nitrogen in the effluent decreased to 2 mg/l without the accumulation of nitrite, and removal of more than 70% of the nitrogen from the input sewage was achieved.     

Post-treatments of anaerobic effluents

Post-treatments are necessary if anaerobic effluents need to be discharged into surface waters, because anaerobic digestion alone is not able to produce effluents that can meet the discharge standards applied in most industrialized countries, particularly for suspended solids, particulate COD, nitrogen, phosphorus and sulphides. This paper has the aim to present some results obtained in the recent years in our laboratory, where different comprehensive processes that include anaerobic digestion have been studied. Discussion will regard: 1) the ANANOX (ANaerobic-ANoxic-OXic) process for the treatment of municipal wastewater; 2) a process studied for the biological removal of C, N and P from piggery wastewater that has a hybrid anaerobic/anoxic reactor as the first treatment step; 3) the use of a Sequencing Batch Reactor for the post-treatment of digested cheese whey mixed with cheese factory cleaning waters.Abbreviations ABR Anaerobic Baffled Reactor - Bv organic volumetric loading rate (gCOD·L^-1·d^-1) - BV bed volumes - F/M food to microorganism ratio or sludge loading rate (gCOD·g.VSS^-1·d^-1) - HRT hydraulic retention time (t) - JHB University of Johannesburg nutrient removal process - p.e. person equivalent - Qrd recycle for denitrification flow rate - Qrs sludge recycle flow rate - SBR Sequencing Batch Reactor - TKN Total Kjeldahl Nitrogen - VCF Volumetric Concentration Factor (vol. permeate/vol. retentate)     

Nitrogen removal via simultaneous partial nitrification,anammox and denitrification (SNAD) process under high DO condition

The simultaneous partial nitrification, anammox and denitrification (SNAD) process for treating domestic wastewater was investigated in a sequencing batch reactor (SBR). The SBR was operated with air flow rate of 500 L h^?1 at 30 °C. Domestic wastewater was used as influent and Kaldnes rings were used as biomass carriers. In the beginning, long aeration condition was implemented to cultivate nitrification biofilm. Afterwards, intermittent aerobic condition was conducted during the cycle operation. The influent organic matter loading rate was improved by reducing the aeration and mixing times. Consequently, when the SNAD biofilm reactor was fed with the organic matter loading rate of 0.77 (kg COD m^?3 d^?1), the bio-bubbles appeared in the reactor and the total inorganic nitrogen (TIN) removal efficiency decreased. After the organic matter loading rate decreased to 0.67 (kg COD m^?3 d^?1), the reactor showed excellent nitrogen removal performance. The TIN removal efficiency varied between 80 and 90 %, and the average TIN removal loading rate was 0.22 (kg TIN m^?3 d^?1). Additionally, the scanning electron microscope (SEM) observation confirmed that the anammox bacteria located in the inner part of the carriers. Finally, the microbial community analysis of 16S rRNA gene cloning revealed that the anammox bacteria on the carriers consisted of three main genuses: Candidatus Brocadia sp., Candidatus Brocadia caroliniensis and Candidatus Brocadia fulgida.     

Microbial community composition and dynamics of moving bed biofilm reactor systems treating municipal sewage

Moving bed biofilm reactor (MBBR) systems are increasingly used for municipal and industrial wastewater treatment, yet in contrast to activated sludge (AS) systems, little is known about their constituent microbial communities. This study investigated the community composition of two municipal MBBR wastewater treatment plants (WWTPs) in Wellington, New Zealand. Monthly samples comprising biofilm and suspended biomass were collected over a 12-month period. Bacterial and archaeal community composition was determined using a full-cycle community approach, including analysis of 16S rRNA gene libraries, fluorescence in situ hybridization (FISH) and automated ribosomal intergenic spacer analysis (ARISA). Differences in microbial community structure and abundance were observed between the two WWTPs and between biofilm and suspended biomass. Biofilms from both plants were dominated by Clostridia and sulfate-reducing members of the Deltaproteobacteria (SRBs). FISH analyses indicated morphological differences in the Deltaproteobacteria detected at the two plants and also revealed distinctive clustering between SRBs and members of the Methanosarcinales, which were the only Archaea detected and were present in low abundance (<5%). Biovolume estimates of the SRBs were higher in biofilm samples from one of the WWTPs which receives both domestic and industrial waste and is influenced by seawater infiltration. The suspended communities from both plants were diverse and dominated by aerobic members of the Gammaproteobacteria and Betaproteobacteria. This study represents the first detailed analysis of microbial communities in full-scale MBBR systems and indicates that this process selects for distinctive biofilm and planktonic communities, both of which differ from those found in conventional AS systems.     

Effects of temperature, salinity, and carbon: nitrogen ratio on sequencing batch reactor treating shrimp aquaculture wastewater

In order to improve the water quality in the shrimp aquaculture, we tested a sequencing batch reactor (SBR) for the treatment of shrimp wastewater. A SBR is a variation of the activated sludge biological treatment process. This process uses multiple steps in the same tank to take the place of multiple tanks in a conventional treatment system. The SBR accomplishes pH correction, aeration, and clarification in a timed sequence, in a single reactor basin. This is achieved in a simple tank, through sequencing stages, which includes fill, react, settle, decant, and idle. The wastewater from the Waddell Mariculture Center, South Carolina was successfully treated using a SBR. The wastewater contained high concentration of carbon and nitrogen. By operating the reactor sequentially, viz, aerobic, anaerobic, and aerobic modes, nitrification and denitrification were achieved as well as removal of carbon. We optimized various environmental parameters such as temperature, salinity, and carbon and nitrogen ratio (C:N ratio) for the best performance of SBR. The results indicated that the salinity of 28-40 parts per thousand (ppt), temperature range of 22-37 degrees C, and a C:N ratio of 10:1 produced best results in terms of maximum nitrogen and carbon removal from the wastewater. The SBR system showed promising results and could be used as a viable treatment alternative in the shrimp industry.     

厌氧氨氧化工艺的应用现状和问题

厌氧氨氧化(Anaerobic ammonium oxidation,ANAMMOX)工艺因其高效低耗的优势,在废水生物脱氮领域具有广阔的应用前景。在过去的20年中,许多基于ANAMMOX反应的工艺得以不断研究和应用。预计到2014年末,全球范围内的ANAMMOX工程将会超过100座。综述了各种形式的ANAMMOX工艺,包括短程硝化-厌氧氨氧化、全程自养脱氮、限氧自养硝化反硝化、反硝化氨氧化、好氧反氨化、同步短程硝化-厌氧氨氧化-反硝化耦合、单级厌氧氨氧化短程硝化脱氮工艺。对一体式和分体式工艺运行条件进行了比较,结合ANAMMOX工艺工程(主要包括移动床生物膜,颗粒污泥和序批式反应器系统)应用现状,总结了工程化应用过程中遇到的问题及其解决对策,在此基础上对今后的研究和应用方向进行了展望。今后的研究重点应集中于运行条件的优化和水质障碍因子的解决,尤其是工艺自动化控制系统的开发和特殊废水对工艺性能影响的研究。