Performance of a Biofilm Airlift Suspension Reactor for Synthetic Wastewater Treatment

Performance stability of a biofilm airlift suspension reactor (BASR) was studied using ethanol as a substrate. The main objective of this research was to investigate the applicability of the reactor as a wastewater treatment process by examining the effects of soluble chemical oxygen demand (SCOD) loading rate and hydraulic retention time (HRT) on the performance of the reactor. SCOD removal of 90% or higher was achieved at an HRT of 45 min with loading rates from 10 to 18 kg SCOD/m3?day. Similar results were obtained at HRTs of 60 and 90 min and a SCOD loading rate of 10 kg SCOD/m3?day. Nitrification occurred in the system when the ratio of SCOD to ammonia nitrogen was changed from 10:1 to 6:1. The morphology of the biofilm in the BASR was denser and thicker when nitrifiers grew in the biofilm. Filamentous overgrowth was observed from time to time and proper chlorine dose successfully suppressed its growth. The oxygen uptake rate was an effective tool for monitoring the effect of chlorination.     

内循环撞击流生物膜反应器处理高氨氮废水试验研究

[目的]研究内循环撞击流生物膜反应器处理高浓度氧氯废水的性能.[方法]采用内循环撞击流生物膜反应器,以玉米芯为生物栽体处理模拟高氨氮废水,探讨了C/N比、溶解氧(DO)对COD和NH4+-N去除效果的影响.[结果]在进水NH4+-N 200 mg/L、DO 2mg/L、C/N比分别为1.0和1.5时,对COD的去除效果没有明显影响,均高达92%以上;C/N为1.5时,COD和NH4+-N平均去除率最高,分别达92.7%和41.2%;在C/N为2.0时,去除率显著降低,COD和NH4+-N平均去除率分别降至20%和10%左右;在C/N为1.5、NH4+-N 200 mg/L时,DO对COD的去除影响不大,但对NH4+-N的去除影响较大,DO浓度从4 mg/L降到1 mg/L时,NH4+-N去除率从46.4%降至17.1%.[结论]该研究为高氨氮废水处理提供了理论依据.     

Immobilized-Cell Membrane Bioreactor for High-Strength Phenol Wastewater

An immobilized-cell membrane bioreactor was fabricated to investigate degradation of phenol at high concentrations using Pseudomonas putida American Type Culture Collection 49451. In the case of suspension cultures, P. putida utilized phenol at concentrations below 1,000 mg∕L, but experienced substrate inhibition at higher concentrations. On the other hand, cells immobilized in 25% by weight polysulfone fibers degraded phenol at concentrations above 1,000 mg∕L. At an initial phenol concentration of 1,200 mg∕L, phenol was fully degraded within 95 h in the immobilized system, whereas no cell growth and phenol degradation were observed in the free suspension system at 1,000 mg∕L phenol. In the immobilized system, it was observed that cells diffused from the membranes when phenol concentrations reached noninhibitory levels in a few experiments. In such cases, the time taken for complete degradation was shorter with cell diffusion because suspension cells were responsible for the rapid phenol degradation. Further biodegradation studies at phenol concentrations of 2,000 and 3,500 mg∕L were also performed to evaluate the effectiveness of cell immobilization for delaying the effects of substrate inhibition. Phenol could be completely degraded at both high concentrations.     

Mathematical Model for the Biofilm–Activated Sludge Reactor

A steady state mathematical model is developed for describing the completely mixed biofilm–activated sludge reactor (hybrid reactor). The model is derived by simultaneously considering Monod kinetics expressions and Fickian’s diffusion theory for substrate in biofilm. In addition, it includes the basic concepts, which describe both culture (suspended and attached) and the competition between them for limiting substrate. By using this model the suspended biomass concentration can be obtained for this system. Subsequently, the other remaining parameters of the system can be computed. Therefore it helps to design and operate the hybrid reactor under different conditions for any given set of kinetic parameters. The utility of the model has been explained for a given set of data and verified by comparing with another solution. It is found that for the same set of data, the model is accurate in the results. The model has been presented in more than one form, each form having an explicit solution of the system. Compared with other solutions of such a system, the model provides a good tool for describing such a system based on fundamental principles.     

Treatment of High-Strength Pharmaceutical Wastewater and Removal of Antibiotics in Anaerobic and Aerobic Biological Treatment Processes

Anaerobic and aerobic treatment of high-strength pharmaceutical wastewater was evaluated in this study. A batch test was performed to study the biodegradability of the wastewater, and the result indicated that a combination anaerobic-aerobic treatment system was effective in removing organic matter from the high-strength pharmaceutical wastewater. Based on the batch test, a pilot-scale system composed of an anaerobic baffled reactor followed by a biofilm airlift suspension reactor was designed. At a stable operational period, effluent chemical oxygen demand (COD) from the anaerobic baffled reactor ranged from 1,432 to 2,397?mg/L at a hydraulic retention time (HRT) of 1.25 day, and 979 to 1,749?mg/L at an HRT of 2.5 day, respectively, when influent COD ranged from 9,736 to 19,862?mg/L. As a result, effluent COD of the biofilm airlift suspension reactor varied between 256 and 355?mg/L at HRTs of from 5.0 to 12.5 h. The antibiotics ampicillin and aureomycin, with influent concentrations of 3.2 and 1.0?mg/L, respectively, could be partially degraded in the anaerobic baffled reactor: ampicillin and aureomycin removal efficiencies were 16.4 and 25.9% with an HRT of 1.25 day, and 42.1 and 31.3% with HRT of 2.5 day, respectively. Although effective in COD removal, the biofilm airlift suspension reactor did not display significant antibiotic removal, and the removal efficiencies of the two antibiotics were less than 10%.     

Oxygen Transfer Model for a Flow-Through Hollow-Fiber Membrane Biofilm Reactor

A mechanistic oxygen transfer model was developed and applied to a flow-through hollow-fiber membrane-aerated biofilm reactor. Model results are compared to conventional clean water test results as well as performance data obtained when an actively nitrifying biofilm was present on the fibers. With the biofilm present, oxygen transfer efficiencies between 30 and 55% were calculated from the measured data including the outlet gas oxygen concentration, ammonia consumption stoichiometry, and oxidized nitrogen production stoichiometry, all of which were in reasonable agreement. The mechanistic model overpredicted the oxygen transfer by a factor of 1.3 relative to the result calculated from the outlet gas oxygen concentration, which was considered the most accurate of the measured benchmarks. A mass transfer coefficient derived from the clean water testing with oxygen sensors at the membrane-liquid interface was the most accurate of the predictive models (overpredicted by a factor of 1.1) while a coefficient determined by measuring bulk liquid dissolved oxygen underpredicted the oxygen transfer by a factor of 3. The mechanistic model was found to be an adequate tool for design because it used the published diffusion and partition coefficients rather than requiring small-scale testing to determine the system-specific mass transfer coefficients.     

Procedure to Quantify Biofilm Activity on Carriers Used in Wastewater Treatment Systems

A procedure is presented for evaluating and comparing the biological activity of biofilms attached to various biofilm carriers by measurement of the glucose consumption rate. This technique allows for the economical design and selection of small particulate biofilm carriers that will maximize substrate removal when used in industrial-scale fluidized bioreactors. Methods for ensuring reproducible results are described. To support the glucose consumption rate findings, biofilm dry weights were obtained at the conclusion of activity rate experiments, and scanning electron micrographs were taken to evaluate the presence of biofilm and to view surface characteristics. Fourteen different biofilm carriers were evaluated ranging from commercially available products to novel carriers designed specifically for this study. Carriers that exhibited the highest reaction rates in descending order included: Syntrex 1220 (Kinetico, Inc.), Kaldnes Carrier Element—Modified (Kaldnes North America, Inc.), Kaldnes Carrier Element—Original (Kaldnes North America, Inc.), Macrolite Modified CEPP-02 (Kinetico, Inc.), Macrolite 357 (Kinetco, Inc.), and Virgin Foam Cubes (BB Bradley Co.). Results showed that the accumulation of biofilm depended most strongly on carrier surface properties, such as surface roughness and specific surface area. The biofilm activity as measured by glucose consumption rate correlated well with activity determinations made by COD measurements when a complex carbohydrate was used as substrate in place of glucose. Substrate consumption rates in microreactors were within ±43% of those measured in a 3-L bioreactor. The method presented here produced highly reproducible results and may be used to accurately and economically screen a large number of newly-designed carriers for application in industrial bioreactor processes.     

涡流反应器在某有色冶炼污水处理中的应用

介绍了涡流反应器在某有色金属冶炼废水处理中的应用,涡流反应器较好的解决了有色金属冶炼废水中高浓度氯离子对金属的强腐蚀问题,同时提高了水处理效率.     

改良式连续流序批反应(MSBR)工艺处理混合废水的技术开发与应用

通过对水质的分析,选用最优的处理流程,以改良式连续流序批反应(MSBR)为核心工艺,使处理后水质达到使用标准.     

Bed Voidage Correlation in Fluidized Bed Biofilm Reactor

A simple predictive correlation for bed voidage in a three-phase fluidized bed biofilm reactor (FBBR) has been proposed in this study, based on a relationship between the effective up-flow superficial liquid velocity (UL) and the corresponding up-flow superficial liquid velocity in a three-phase FBBR (UL′). The experimental observations of bed voidage both for this study as well as for experimental data from a study published by Trinet et al. for a three-phase FBBR compared reasonably well with the model predictions developed in this study, with mean deviations of 0.26% and 7%, respectively. Further, published experimental observations of bed voidage in a two-phase FBBR agreed well with the model predictions, with mean deviations of 26.4%, 5.2%, and 9.7% for studies conducted by Mulcahy and Shieh, Ngian and Martin, and Setiadi, respectively, and with a mean deviation of 18.7% for the total published experimental data (297 points) of the above researchers.     

Nitrification at Low Oxygen Concentration in Biofilm Reactor

A nitrification process under low dissolved oxygen (DO) concentration is proposed in a completely stirred biofilm reactor. The reactor was fed with a synthetic wastewater containing 250 mg NH4–N∕L. A stable nitrite accumulation in the effluent was obtained during >110 days' operation; NO2–N:(NO2–N + NO3–N) in the effluent reached >90% under 0.5 mg DO∕L. Ammonium was completely converted and NH4–N in the outlet was as low as 5 mg∕L. A transient increase of the DO concentration in the reactor induced a complete conversion of ammonia and nitrite to nitrate after only 2 days. A return to a low DO concentration again induced nitrite accumulation. These results show that the nitrite oxidizers were always present in the reactor but were outcompeted at low DO concentration, due to their lower affinity for oxygen, compared with ammonia oxidizers. Nitrite accumulation could also be favored by free nitrous acid accumulation inside the biofilm.     

升流式生物反应器处理含锰废水的中试研究

研究目的在于提供一种处理含锰废水的新方法。采用生物反应器的技术处理锰矿企业排放的含锰废水。在优化的环境及技术条件下,对原水锰浓度在3000mg／L左右的废水的平均去除效率可达87％以上。利用微生物处理含锰废水成本低,具有良好的经济效益,是传统方法以外的处理含锰废水的新思路。     

Biostorage Polymers Phenomena in Cheese Wastewater Treatment by a Sequencing Batch Reactor

Typically, microbes associated with biological wastewater treatment processes are subjected to dynamic organic and nutrient loading conditions. This constantly changing environment imposes a stress, referred to as “feast-famine” that selects for microbes capable of biologically storing substrates as polymers during high organic concentration periods (i.e., feast) for use during periods of low organic availability (i.e., famine). In this study, we monitored the production of biostorage polymers generated with actual cheese wastewater treatment by way of sequencing batch reactors (SBRs). SBRs were employed and operated in duplicate under two long (i.e., hours) filling scenarios (1) “react fill” with mixing/aeration and (2) “static fill” with no mixing/aeration. Despite comparable effluent water quality levels, the results reveal that a “static fill” approach outperforms a “react fill” with respect to maximum biostorage polymer production (50% more poly-β-hydroxybutyrate, 15% more glycogen). The presence of biostorage polymer production has been shown to be indicative of a more stable and robust process.     

内循环厌氧反应器处理印染废水研究

印染行业是工业废水排放大户,印染废水具有水量大、有机污染物含量高、色度深、碱性大、水质变化大等特点,属于难处理的工业废水。文章设计了一种改进型的内循环厌氧反应器,克服了传统内循环厌氧反应器结构复杂、易引起堵塞等缺点,并对改进型内循环厌氧反应器的启动周期、有机负荷、COD去除效率、反应器的控制参数等进行了实验研究。     

Biodegradation of PCE in a Hybrid Membrane Aerated Biofilm Reactor

A continuous flow flat sheet hybrid membrane aerated biofilm reactor (MABR) was used to treat a synthetic wastewater containing perchloroethylene (PCE); 1.25–2.5?g chemical oxygen demand (COD)/L of glucose was also added to the synthetic wastewater as a source of COD representative of a real wastewater. The reactor was able to biodegrade 70?mg?L?1 of PCE in 9?h without the accumulation of any intermediate compounds, resulting in a removal rate of 247?mmol of PCE?h?1?m?3 in a reactor with a specific membrane area of 4.048?m2?m?3. MABRs have never been used before for PCE degradation, and this rate is one of the highest volumetric PCE degradation rates reported in the literature. COD removal was also good and varied from 85 to 92%. Since very few volatile fatty acids accumulated in the system, most of the residual COD was attributed to soluble microbial products as reported by previous researchers. A mass balance on chloride during this study showed that only 72–81% of it could be accounted for. It is probable that some of the chlorinated ethenes were adsorbed onto the biofilm or that aerobic intermediates of low-chlorinated compounds such as trichloroethanol, dichloroacetyl, and chloroacetaldehyde were produced in the system. Nevertheless the chloride mass balance in this work compares well with the literature. Due to their high PCE and COD removal rates, hybrid MABRs have the potential to be used for a number of refractory organics which require combined anaerobic/aerobic biological treatment for degradation.     

Toward Polyhydroxyalkanoate Production Concurrent with Municipal Wastewater Treatment in a Sequencing Batch Reactor System

Bacteria can synthesize cytoplasmic granules known as polyhydroxyalkanoates (PHAs), which are carbon and energy storage reserves, from organic carbon when subject to stressful environmental conditions. PHAs are also biodegradable thermoplastics with many potential commercial applications. The purpose of the research reported herein was to evaluate the feasibility of integrating PHA production within a municipal wastewater treatment (WWT) configured as a sequencing batch reactor (SBR). Four bench-scale WWT SBRs were tested at decreasing organic loading rates to assess the potential to enrich for microbes capable of feast/famine PHA synthesis. For each treatment SBR, sidestream batch reactors receiving higher quantities of primary solids fermenter liquor were operated to produce PHA. Results from this study demonstrate that a treatment SBR supplied moderate strength wastewater can enrich for the target microorganisms, with PHA yields of 0.23–0.31-mg PHA per mg chemical oxygen demand, and produce high quality effluent. In sidestream batch reactors, microorganisms that fed excess quantities of substrate can rapidly synthesize significant quantities of PHA. Based on the results of this study, we estimate that a 1 million gallon per day SBR WWT-PHA production system could generate 11–36 t (12–40 t) of PHA annually.     

一种新型移动床生物膜反应器应用研究

通过分析一种新型移动床生物膜反应器(MBBR)技术在实际中应用情况,将有关技术参数及应用问题解决方案与其它传统方法作出对比分析,为广大的工程技术人员在实际使用中提供参考。