Treatment of winery wastewater in a full-scale fixed bed biofilm reactor.

The treatment of winery wastewater was performed at full-scale applying a two-stage fixed bed biofilm reactor (FBBR) system for the discharge in the sewerage. The results of the first year of operation at the full-scale plant are presented. Values of removed organic loads and effluent concentrations were interpreted on the basis of the COD fractionation of influent wastewater assessed through respirometric tests. The average removal efficiency of total COD was 91 %. It was not possible to reach an higher efficiency because of the unbiodegradable soluble fraction of COD (about 10% of total COD on average during the whole year), that cannot be removed by biological process or settling. Due to the high empty space offered by the plastic carriers, FBBRs did not require backwashing during the seasonal operationing period of the plant (September-March). In comparison with other treatment systems the FBBR configuration allows one to ensure a simple management, to obtain high efficiency also in the case of higher fluctuations of flow and loads and to guarantee a good settleability of the sludge, without bulking problems.     

厌氧序批式反应器(ASBR)处理啤酒废水的试验研究

考察了ASBR工艺对啤酒废水CODCr去除率和产气率的影响。研究表明,ASBR处理啤酒废水适宜参数为:温度30~40℃,pH7~8,反应时间24h,MLSS5000~5500mg/L。在此工艺参数下连续运行1周,CODCr、TSS去除率分别为80.9%、74%,产气率约为500L/kgCODCr。     

Automatic control strategy for biological nitrogen removal of low C/N wastewater in a sequencing batch reactor.

To establish an automatic control system of external carbon addition in biological nitrogen removal, a bench-scale sequencing batch reactor with real-time control strategy was designed in this study. An oxidation-reduction potential (ORP) profile was used for automatic control of external carbon addition. The mean removal efficiency of total organic carbon was over 98%. Complete denitrification in an anoxic phase and complete denitrification and nitrification in anoxic and oxic phases were accomplished, respectively, because the oxic and anoxic periods were also appropriately controlled with ORP and pH profiles, respectively. Mean removal efficiency of total nitrogen was over 95%. When concentration of influent wastewater was changed, volume of additional carbon was automatically changed with the influent fluctuation, and flexible hydraulic retention time was achieved in this system.     

Optimal biodegradation of phenol and municipal wastewater using a controlled sequencing batch reactor.

This work presents the results of the application of an optimally controlled influent flow rate strategy to biodegrade, in a discontinuous reactor, a mixture of municipal wastewater and different concentrations of phenol when used as a toxic compound model. The influent is fed into the reactor in such a way to obtain the maximal degradation rate avoiding the inhibition of the microorganisms. Such an optimal strategy was able to manage increments of phenol concentrations in the influent up to 7000 mg/L without any problem. It was shown that the optimally controlled influent flow rate strategy is a good and reliable tool when a discontinuous reactor is applied to degrade an industrial wastewater.     

A process-dependent real-time controller for sequencing batch reactor plants: results of full-scale operation.

This paper presents results of a research project, in which a process-dependent real-time control (RTC) strategy for a sequencing batch reactor plant was realised in full-scale. The cycle controller is based on NH4 analysers, NO3 probes, TSS probes and sludge level probes. With this new RTC strategy it was possible to increase the treatment capacity by 50%. By implementation of the new controller the TN, TP and NH4-N treatment efficiency could be improved significantly, too. The treatment efficiency concerning COD is comparable.     

Aerobic granulation in a sequencing batch reactor (SBR) for industrial wastewater treatment.

Aerobic granulation seems to be an a attractive process for COD removal from industrial wastewater, characterised by a high content of soluble organic compounds. In order to evaluate the practical aspects of the process, comparative experimental tests are performed on synthetic and on industrial wastewater, originating from pharmaceutical industry. Two pilot plants are operated as sequencing batch bubble columns. Focus was put on the feasibility of the process for high COD removal and on its operational procedure. For both wastewaters, a rapid formation of aerobic granules is observed along with a high COD removal rate. Granule characteristics are quite similar with respect to the two types of wastewater. It seems that filamentous bacteria are part of the granule structure and that phosphorus precipitation can play an important role in granule formation. For both wastewaters similar removal performances for dissolved biodegradable COD are observed (> 95%). However, a relatively high concentration of suspended solids in the outlet deteriorates the performance with regard to total COD removal. Biomass detachment seems to play a non-negligible role in the current set-up. After a stable operational phase the variation of the pharmaceutical wastewater caused a destabilisation and loss of the granules, despite the control for balanced nutrient supply. The first results with real industrial wastewater demonstrate the feasibility of this innovative process. However, special attention has to be paid to the critical aspects such as granule stability as well as the economic competitiveness, which both will need further investigation and evaluation.     

Coupled anaerobic-aerobic treatment of whey wastewater in a sequencing batch reactor: proof of concept.

A proof of concept was performed in order to verify if the coupling of anaerobic and aerobic conditions inside the same digester could efficiently treat a reconstituted whey wastewater at 21 degrees C. The sequencing batch reactor (SBR) cycles combined initial anaerobic phase and final aerobic phase with reduced aeration. A series of 24 h cycles in 0.5 L digesters, with four different levels of oxygenation (none, 54, 108 and 182 mgO2 per gram of chemical oxygen demand (COD)), showed residual soluble chemical oxygen demand (sCOD) of 683 +/- 46, 720 +/- 33, 581 +/- 45, 1239 +/- 15 mg L(-1), respectively. Acetate and hydrogen specific activities were maintained for the anaerobic digester, but decreased by 10-25% for the acetate and by 20-50% for the hydrogen, in the coupled digesters. The experiment was repeated using 48 h cycles with limited aeration during 6 or 16 hours at 54 and 108 mgO2gCODinitial(-1), displaying residual sCOD of 177 +/- 43, 137 +/- 38, 104 +/- 22 and 112 +/- 9 mgL(-1) for the anaerobic and the coupled digesters, respectively. The coupled digesters recovered after a pH shock with residual sCOD as low as 132 mg L(-1) compared to 636 mg L(-1) for the anaerobic digester. With regard to the obtained results, the feasibility of the anaerobic-aerobic coupling in SBR digesters for the treatment of whey wastewater was demonstrated.     

Nitrogen removal of high strength wastewater via nitritation/denitritation using a sequencing batch reactor.

The sequencing batch reactor (SBR) process concept was applied to achieve efficient ammonium removal via nitrite under both laboratory and pilot-scale conditions. Both sets of experimental results show that without pH control or carbon addition the nitritation process consistently converted approximately 50% of the ammonium from biosolids dewatering liquids to nitrite with hydraulic retention times (HRT) as short as 10 h. The results from the pilot-scale study also indicate that the selective oxidation of ammonium to nitrite is a reliable process as the accumulation of nitrate was never an issue during a 330-day trial. The SBR process concept was extended to achieve complete nitrogen removal through nitritation and denitritation in the laboratory scale. The experimental results indicate that a total reduction of 96-98% of the ammonium nitrogen from biosolids dewatering liquids (influent concentration typically 1,200 g m(-3)) was achieved with a short HRT of 1.1 d and a removal rate of 1.05 kgNm(-3)d(-1). This process concept was tested at pilot scale where the nitritation process could be started up without temperature control in a short period of time. Nitrogen removal rates up to 1.2 kgNm(-3)d(-1) at an HRT of 0.88 d have been obtained. COD to nitrogen ratios required in the pilot plant were consistently in the range 1.6-1.9 kgCOD kg(-1)N removed.     

短程硝化-强化生物除磷序批式反应器处理畜禽养殖废水

畜禽养殖废水有机物水质水量变化大,有机物、氨氮与磷的浓度较高,直接排放会严重危害环境。通过构建厌氧-好氧序批式反应器（SBR）处理预酸化畜禽养殖废水,分析了不同进水负荷条件下反应器对污染物的去除性能和微生物群落结构的变化规律。结果表明：SBR反应器对高负荷进水中TN、PO^3-₄—P和COD的平均去除率可分别达到64.5%、97.5%和94.5%。反应器出现NH⁺₄—N和NO₂—N亚硝酸同时积累的短程硝化现象,这可能与高进水负荷对氨氧化菌和亚硝酸盐氧化菌的活性和种群的影响有关。与乙酸盐相比,以丙酸盐作碳源时污泥的强化生物除磷活性更高。随着进水负荷的增大,聚糖菌（GAOs）的相对丰度明显升高。四联球状菌（Tetrasphaera）为反应器中始终占优势的聚磷菌（PAOs）,对反应器除磷性能有重要贡献。在高有机负荷条件下,SBR内PAOs与GAOs之间不存在明显的底物竞争关系,系统脱氮除磷性能未受影响。     

Performance comparison of a pilot-scale membrane bioreactor and a full-scale sequencing batch reactor with sand filtration: treatment of low strength wastewater from a northern Canadian Aboriginal Community.

Northern Aboriginal communities in Canada suffer from poor wastewater treatment. Treatment systems on 75% of Manitoban Aboriginal communities produce substandard effluent despite the presence of sophisticated treatment systems. A 200-litre, pilot-scale membrane bioreactor (MBR) was established on the Opaskwayak Cree Nation to investigate the feasibility of MBRs in mitigating Aboriginal wastewater treatment issues. The pilot system was remote controlled and monitored via the Internet using the program pcAnywhere. The community utilized two existing sequencing batch reactors (SBR) and three sand filters for wastewater treatment. The community wastewater was relatively weak and highly fluctuating which led to poorly settling sludge that readily fouled the sand filters. A comparison study between the MBR and SBR was undertaken from September to December 2003. Operated at a 10-hour hydraulic retention time and 20-day solids residence time, the MBR outperformed the SBR and sand filtration on BOD and suspended solids removal. Furthermore, the MBR showed high levels of nitrification despite relatively cold water temperatures.     

Enhanced nitrogen removal using C/N load adjustment and real-time control strategy in sequencing batch reactors for swine wastewater treatment.

The laboratory-scale sequencing batch reactor (SBR) was used to study the effectiveness of an integrated strategy of real time control with C/N ratio adjustment for practical swine wastewater treatment. Swine waste was used as the external carbon source for continuous treatment in the SBR reactors. Oxidation-reduction potential and pH were used as parameters to control the continuous denitrification and nitrification process, respectively. A constant effluent quality could be obtained, despite drastic variations in the characteristics of influent wastewater. Also, a relatively complete removal of nutrients was always ensured, since the optimum quantity of the external carbon source could be provided for complete denitrification, and a flexible hydraulic retention time was achieved by the successful real-time control strategy. The average removal efficiencies of total organic carbon and nitrogen were over 94% and 95%, respectively.     

Biodegradation of 4-methylaniline in a sequencing batch reactor

The biodegradation of the aromatic amine 4-methylaniline (4MA) using an aerobic sequencing batch reactor was evaluated. The specific degradation rate showed an exponential increase during the acclimation of the microorganisms reaching a maximal value of 34 mg 4MA/VSS/h. After the acclimation, the process showed a stable operation. A high similarity index was observed, indicating a low variation in the population diversity. During this period, the physicochemical parameters demonstrated a stable operation of the reactor.     

On-site treatment of a motorway service area wastewater using a package sequencing batch reactor (SBR).

A sequencing batch reactor (SBR) treating the effluent of a motorway service station in the south of England situated on a major tourist route was investigated. Wastewater from the kitchens, toilets and washrooms facilities was collected from the areas on each side of the motorway for treatment on-site. The SBR was designed for a population equivalent (p.e.) of 500, assuming an average flow of 100 m3/d, influent biochemical oxygen demand (BOD) of 300 mg/l, and influent suspended solids (SS) of 300 mg/l. Influent monitoring over 8 weeks revealed that the average flow was only 65 m3/d and the average influent BOD and SS were 480 mg/l and 473 mg/l respectively. This corresponded to a high sludge loading rate (F:M) of 0.42 d(-1) which accounted for poor performance. Therefore the cycle times were extended from 6 h to 7 h and effluent BOD improved from 79 to 27 mg/l.     

Start-up and steady-state results of a full-scale UASB reactor treating malting wastewater.

An Imhoff tank was reconstructed into a 250 m3 UASB reactor in order to treat a malting plant wastewater. The UASB was inoculated with sludge from an anaerobic lagoon used for slaughterhouse wastewater treatment. After two months of operation the reactor achieved full load with an HRT of 17 h, a COD removal higher than 80% and a biogas production of 300 m3/day (77% average methane content), with an organic loading rate of 3.6 kgCOD/m3.d (0.24 kgCOD/kgVSS.d). A yield coefficient of 0.09 gVSS/gCODrem was found from a mass balance. The fat present in the inoculated sludge (48 mg/gSSV) did not affect the start up performance. Sludge from the inoculum with high content of fat (270 mg/gSSV), was separated by flotation in the first week of operation. The COD removal efficiency was scarcely influenced by the reactor operation temperature (17-25 degrees C).     

Bioaugmentation of a sequencing batch biofilm reactor by horizontal gene transfer.

Bioaugmentation by introduction of catabolic genes residing on mobile genetic elements into the microbial community of a soil or wastewater environment might be an alternative to bioaugmentation by addition of bacterial cells with chromosomally encoded catabolic genes. This study investigates the possibility to enhance degradation of the xenobiotic model compound 2,4-dichlorophenoxyacetic acid in a sequencing batch biofilm reactor (SBBR) by using the conjugative plasmid pJP4 carrying genes for 2,4-D degradation. After introduction of a plasmid donor strain to a lab-scale SBBR operated without 2,4-D, the number of plasmid-carrying cells first dropped, and then increased after switching to 2,4-D as the sole carbon source. The donor cells were unable to grow in the applied synthetic wastewater with 2,4-D as the sole carbon source. Transconjugants could be detected both by culture-dependent and culture-independent methods in the 2,4-D degrading biofilm. In contrast to 90% 2,4-D degradation in the bioaugmented reactor within 40 h, a control reactor which had not received the plasmid still contained 60% of the initial 2,4-D concentration after 90 h. This experiment clearly demonstrates the introduction of 2,4-D degradative genes into a microbial biofilm and indicates that horizontal gene transfer is a promising tool for bioaugmentation of reactors treating wastewater.     

Utilization of a hybrid sequencing batch reactor (HSBR) as a decentralized system of domestic wastewater treatment

This paper presents the experiments carried out in a hybrid sequencing batch reactor (HSBR), used for biological treatment of sewage. The HSBR was built in a cylindrical shape and made of stainless steel, with a volume of 1.42 m3. Besides the biomass in suspension, the reactor also carried fixed biomass (hybrid process), adhered in the support material. This consisted of a nylon net disposed in a grille for biofilm biomass adhesion. The reactor worked fully automated in operational cycles of maximum 8 hours each, presenting the following phases: filling, anoxic, aerobic, settle and draw of treated effluent, with 3 fillings per cycle. Increasing organic loads (0.14 to 0.51 kg TCOD/m3 day) and ammonium loads (0.002 to 0.006 kg NH4-N/m3.day) were tested. We monitored the reactor's performance by measuring the liquid phase (COD, pH, temperature, DO, nitrogen and phosphorus) during the cycles and by measuring the sludge through respirometric tests. The results obtained demonstrated TCOD removal efficiency between 73 and 96%, and ammonium removal efficiency between 50 and 99%. At the end of the cycles, the effluent presented ammonium concentration <20 mg/L, meeting the Brazilian environmental legislation standards (CONAMA 357/2005) regarding discharges into the water bodies. Respirometric tests showed biomass dependency on FCOD concentrations. Results have demonstrated the potential of this type of reactor for decentralized treatment of domestic wastewater.     

Enrichment of activated sludge in a sequencing batch reactor for polyhydroxyalkanoate production.

The paper describes the start up of a process for the production of polyhydroxyalkanoates (PHAs) from activated sludge. The excess sludge from a wastewater treatment plant was inoculated in a lab-scale sequencing batch reactor (SBR) to be enriched under aerobic conditions through intermittent feeding with a mixture of organic acids. Enriching of activated sludge was monitored through the measurement of polymer concentrations either in the mixed liquor or in the microbial biomass. The bacterial population dynamics during the SBR start up was followed through denaturing gradient gel electrophoresis and the main species present at the steady state were identified. All the measured parameters significantly changed in the SBR during first two weeks after the inoculum was seeded into the reactor, they then stabilized. At the steady state, the SBR produced 2.6 gVSSl(-1) d(-1), with a PHA content of 11% (on a COD basis). The enriched microbial biomass was then transferred into a batch reactor where the bacterial polymer content was increased through a new feeding. In the final batch stage, maximum storage rate and maximum polymer content in the biomass were 405 mgCOD gCOD(-1) h(-1) and 44% (on a COD basis), respectively. The PHA storage from the enriched microbial biomass was about 20 times faster and the PHA content was about 4 times higher than that of the inoculated activated sludge. Observations by fluorescence microscopy showed that the majority of microorganisms in the enriched biomass could be stored. Among the numerically most representative genera in the enriched biomass, Thauera, Candidatus Meganema perideroedes, and Flavobacterium were identified.     

Optimizing sequencing batch reactor (SBR) reactor operation for treatment of dairy wastewater with aerobic granular sludge

The biological wastewater treatment using aerobic granular sludge is a new and very promising method, which is predominantly used in SBR reactors which have higher volumetric conversion rates than methods with flocculent sludge. With suitable reactor operation, flocculent biomass will accumulate into globular aggregates, due to the creation of increased substrate gradients and high shearing power degrees. In the research project described in this paper dairy wastewater with a high particle load was treated with aerobic granular sludge in an SBR reactor. A dynamic mathematical model was developed describing COD and nitrogen removal as well as typical biofilm processes such as diffusion or substrate limitation in greater detail. The calibrated model was excellently able to reproduce the measuring data despite of strongly varying wastewater composition. In this paper scenario calculations with a calibrated biokinetic model were executed to evaluate the effect of different operation strategies for the granular SBR. Modeling results showed that the granules with an average diameter of 2.5 mm had an aerobic layer in between 65-95 microm. Density of the granules was 40 kgVSS/m3. Results revealed amongst others optimal operation conditions for nitrogen removal with oxygen concentrations below 5 gO2/m3. Lower oxygen concentrations led to thinner aerobic but thicker anoxic granular layers with higher nitrate removal efficiencies. Total SBR-cycle times should be in between 360-480 minutes. Reduction of the cycle time from 480 to 360 minutes with a 50% higher throughput resulted in an increase of peak nitrogen effluent concentrations by 40%. Considering biochemical processes the volumetric loading rate for dairy wastewater should be higher than 4.5 kgCOD/(m3*d). Higher COD input load with a COD-based volumetric loading rate of 9.0 kgCOD/(m3*d) nearly led to complete nitrogen removal. Under different operational conditions average nitrification rates up to 5 gNH/(m3*h) and denitrification rates up to 3.7 gNO/(m3*h) were achieved.     

Optimisation of sanitary landfill leachate treatment in a sequencing batch reactor

A bench-scale SBR was operated for almost three years in an attempt to optimise the treatment of leachates generated in old landfill. The results of the first two years were used to design a monitoring and control system based on artificial intelligence concepts. Nitrogen removal was optimized via the nitrite shortcut. Nitrification and N removal were usually higher than 98% and 90%, respectively, whereas COD (of the leachate) removal was approximately 30-40%. The monitoring and control system was demonstrated capable of optimizing process operation, in terms of phase length and external COD addition, to the varying loading conditions. Using the control system developed, a significant improvement of the process was obtained: COD and N load were increased (HRT decrease) and a significant decrease (approximately 34%) of the ratio of COD added to N leachate content was observed.     

Performances of a granular sequencing batch reactor (GSBR).

Aerobic granulation in sequencing batch reactors is widely reported in literature and in particular in SBAR (Sequencing batch airlift reactor) configuration, due to the high localised hydrodynamic shear forces that occur in this type of configuration. The aim of this work was to observe the phenomenon of the aerobic granulation and to confirm the excellent removal efficiencies that can be achieved with this technology. In order to do that, a laboratory-scale plant, inoculated with activated sludge collected from a conventional WWTP, was operated for 64 days: 42 days as a SBAR and 22 days as a SBBC (sequencing batch bubble column). The performances of the pilot plant showed excellent organics removal. COD and BOD removal efficiencies were respectively, 93 and 94%; on the contrary, N-removal efficiency was extremely low (5%-45%/o). The granules dimensions increased during the whole experimentation; change of reactor configuration contributed to further improve this aspect. The experimental work confirmed the essential role of hydraulic settling time in the formation of aerobic granules and in the sludge settleability and the need to find an optimum between granule size and oxygen supply to achieve good N-removal efficiency.