Pertubated loading of a formaldehyde waste in an anaerobic granular activated carbon fluidized bed reactor

The objective of this study was to examine the biological treatment of a formaldehyde waste simulating wastewater from a resin production facility. An analysis of degradation of a high strength organic waste stream containing formaldehyde in an anaerobic fluidized bed granular activated carbon bioreactor (AFBGAC) is presented. In the first part of this study, the AFBGAC bioreactor was operated for a total of 700 days under four different continuous loading rates, to optimize the hydraulic retention time, until steady state performance was obtained. In the second part, the effect of substrate perturbation on effluent quality was examined by periodically loading the reactor using five distinct perturbation schemes to simulate different production shifts. The feed under the first three perturbation schemes was applied in cycles of 16 h on and 8 h off, 12 h on and 12 h off, and 8 h on and 16 h off. The fourth scheme applied feed at 8 h on and 16 h off with no feed on weekends. The fifth scheme examined the long-term effect of substrate limitation using the 8 h on and 16 h off loading cycle with a feed interruption of 9 days. The organic loading per day was kept constant throughout the feed perturbation study. The reactor removed more than 95% of the dissolved organic carbon content of the waste under both continuous and cyclic loading. Formaldehyde removal rates of up to 99.99% were achieved under continuous loading while removal rates ranged from 97.4% to 99.9% under cyclic loading. Although the AFBGAC failed occasionally due to excessive buildup of attached biomass during the phase of continuous loading, it still maintained excellent overall removal efficiencies. It also showed resilience to substrate limitations and load perturbations under dynamic loadings. The results presented in this study provide a promising strategy to treat inhibitory wastes.     

Treatment of anaerobically pre-treated domestic sewage by a rotating biological contactor.

The performance of a rotating biological contactor (RBC) for the post-treatment of the effluent of an up-flow anaerobic sludge blanket (UASB) was the subject of this study. Different hydraulic and organic loading rates have been investigated. The removal efficiencies of COD(total), COD(suspended), COD(colloidal) and COD(soluble) increased at a higher hydraulic retention time (HRT) and a lower influent organic loading rate. The results obtained indicated that a two-stage RBC reactor at an HRT of 10 h and an organic loading rate of 6.4g COD m(-2) d(-1) represents an effective post-treatment process. Most COD(suspended) and COD(colloidal) were removed in the first stage while nitrification proceeded in the second stage. The overall nitrification efficiency was 92% at an ammonia loading rate of 1.1 gm(-2) d(-1). Total E. coli removal at HRTs of 10, 5 and 2.5h were 99.5%, 99.0% and 89.0%. respectively. The major part of suspended E. coli ( >4.4 microm) was removed by sedimentation or by adsorption in the biofilm of the first stage of RBC (99.66%). However, E. coli in the colloidal fraction (<4.4 to >0.45 microm) was eliminated in the second stage of RBC (99.78%). A comparison of the performance of a one-stage versus two-stage RBC system, operated at the same total loading rate, revealed an improvement in the effluent quality of the two-stage effluent as compared to the one-stage effluent. The two stages RBC were used to examine the effect of hydraulic shock loads on reactor performance in terms of COD, nitrification and E. coli removal.     

Anaerobic filter reactor performance for the treatment of complex dairy wastewater at industrial scale

The wastewaters discharged by raw milk quality control laboratories are more complex than the ones commonly generated by dairy factories because of the presence of certain chemicals such as sodium azide or chloramphenicol, which are used for preserving milk before analysis. The treatment of these effluents has been carried out in a full-scale plant comprising a 12 m(3) anaerobic filter (AF) reactor and a 28 m(3) sequential batch reactor (SBR). After more than 2 years of operation, a successful anaerobic treatment of these effluents was achieved, without fat removal prior to the anaerobic reactor. The organic loading rates maintained in the AF reactor were 5-6 kg COD/m(3) d, with COD removal being higher than 90%. No biomass washout was observed, and most of the fat contained in the wastewaters was successfully degraded. The addition of alkalinity is crucial for the maintenance of a proper buffer medium to ensure pH stability. The effluent of the AF reactor was successfully treated in the SBR reactor, and a final effluent with a COD content below 200 mg/l and total nitrogen below 10mg N/l was obtained.     

Response of the anaerobic fluidized bed reactor to transient changes in process parameters

Anaerobic fluidized bed reactors treating a high strength dairy type waste water were subjected to transient decreases in temperature and increases in influent flowrate or COD for 4 and 8 h periods. The quality of the effluent deteriorated during a shock load but returned to normal steady state values 6–22 h after original conditions had been restored, the stability of the reactor during increases in influent COD were found to be influenced by the bicarbonate buffering capacity of the feed.     

Operating characteristics of the aerated submerged fixed-film (ASFF) bioreactor

A multi-stage fixed-film reactor was developed in which a stationary submerged biofilm is attached to ceramic tiles under diffused aeration. Tracer studies revealed that the reactor's hydraulic regime is described by a CSTR-in-series model. Reactor performance at 20 °C was examined using sucrose wastewaters with organic strength up to 900 mg l⁻¹ COD, at hydraulic loadings up to 0.1 m³ m⁻²d⁻¹ and organic loadings up to 90 g CODm⁻² d⁻¹. The reactor demonstrated the capability of achieving 97% soluble COD removals at low loadings and exhibited efficient and stable performance at high hydraulic and organic loadings. Even at application rates near the rate-limiting mass loadings, there was only a 9% loss in efficiency. Reactor operation at high loadings appears to be advantageous since organic substrate removal rates and attached biomass per unit surface area increased with the increase in organic loading. This can be attributed to the good oxygen transfer and the considerable quantity and type of attached biomass attained. Staging of the reactor proved to be effective in eliminating short circuiting and damping excessive loadings, although the majority of COD removal occurs in the first stage which retains the greatest quantity of attached biomass. A good quality effluent was produced.     

AmOn一体化污水生物处理装置的开发

AmOn一体化反应器将传统生物处理工艺的反应、沉淀和污泥回流集中于一个反应器中完成,并以自主开发的新型射流扩散式曝气代替了传统的鼓风曝气、表面曝气等形式,反应器的容积负荷大,水力停留时间短,节省了基建投资与运行费用,降低了操作管理强度,增加了系统运行的可靠性。通过自控系统的调节,可根据不同进水水质和出水要求,沿反应进程自动调节曝气量和搅拌程度,根据要求实现脱氮和除磷,具有广阔的应用前景。     

MIC反应器处理抗生素发酵废液的研究

采用逐步提高抗生素浓度和有机负荷(OLR)的方法,考察改进型内循环厌氧反应器(MIC反应器)对含万古霉素(VA)发酵废液的处理效果,并对微生物群落进行分析。结果表明,污泥经过驯化后,MIC反应器对VA发酵废液有较好的处理能力,当进水VA浓度为70 mg/L左右、水力停留时间(HRT)为4 d时,对MIC反应器运行没有抑制效应,此时COD去除率约为90%,VA去除率达到90%以上;当HRT为2 d、进水OLR为25 kgCOD/(m^3·d)时,MIC反应器对VA发酵废液的COD去除负荷最大,为19.5 kg/(m^3·d)。通过微生物多样性检测结果发现,细菌群落在门水平上的优势菌为Bacteroidetes和Firmicutes。     

Polyphosphate buffering by biomass with different phosphorus contents

Polyphosphate buffering is a novel application of enhanced biological phosphorus (P) removal (EBPR) for P-deficient wastewaters with influent organic load variability. This study investigated the effect of biomass P content on polyphosphate buffering using a membrane bioreactor (MBR) and conventional bioreactor (CBR). Increasing the biomass P content increased polyphosphate buffering and the COD removal capacity, but at high P content (i.e. 20% P/TSS) the effluent P levels increased and a smaller fraction of available P was used for buffering. The MBR produced lower total effluent TSS levels and lower P levels than the CBR at both medium biomass P content (i.e. 12% P/TSS) and at low P content (i.e. 5% P/TSS) when the COD removal capacity was not exceeded. At high biomass P content, the MBR and CBR produced elevated effluent P levels. This study showed that the MBR does not make polyphosphate buffering feasible at high P content.     

复合膜生物反应器的除污性能研究

采用自行设计研制的复合膜生物反应器处理模拟生活污水，考察了系统的除污性能。结果表明，在HRT为9h、SRT为30d、DO为2～3．5mg／L的条件下，系统对COD、NH3-N和浊度具有较好的去除效果，平均去除率分别为90％、89％和90％。生物降解主要承担了对COD和NH3-N的去除作用，膜截留起到了稳定出水水质及去除浊度物质的作用。     

菱形翼片隔板絮凝反应器的研发及应用

基于后台阶流理论,设计了菱形翼片隔板絮凝反应器,实现了同时对流体微观涡旋强化及宏观涡旋均布进行有效控制。同时结合数值模拟计算结果和中试处理效果,优化了菱形翼片隔板絮凝反应器的特征尺寸参数,并将其用于钢厂废水回用项目。工程运行结果表明,单套设备处理量为750 m3/h,出水浊度可稳定在1 NTU左右,对COD的去除率达到了48.5%,大大降低了后续处理负荷,由此证明该设备具有较高的絮凝反应效率,出水水质良好,适用于钢厂废水回用工程。     

Anaerobic treatment of domestic sewage with a rotating stationary fixed-film reactor

An anaerobic reactor was developed for on-site and small scale wastewater treatment applications. The up-flow fixed-film reactor was packed with two different types of circular media: stationary and rotating. Experimental results showed the reactor can treat primary settled domestic wastewaters efficiently, under different operating conditions. At 29°C the mixing action did not improve the organic matter removal efficiencies (65% COD removal was obtained with an organic load of 1.7 kg COD m⁻³ day⁻¹ and a 6 h space time). However, at 16°C the removal efficiency was greatly dependent on the mixing conditions: a gentle agitation (5 rpm) up-graded significantly the reactor operation, but no improvement was observed beyond 15 rpm. It appears that at low temperatures liquid biofilm mass transfer is the rate limiting step when treating sewage anaerobically. Gas production was rather limited [0.11 m³ (STP) kg⁻¹ COD removed] and calculations suggest that more than 50% of the total CH₄ produced is lost due to its dissolution in the effluent. Improved effluent quality, reduced sludge production (0.11 kg TSS kg⁻¹ COD supplied), low energy requirements and low maintenance needs make this reactor a good, compact alternative to conventional household wastewater treatment processes.     

复合式竹丝填料生物反应器处理化粪池出水

为寻找适合化粪池出水的处理工艺,采用批式试验研究了复合式竹丝填料生物反应器对化粪池出水中COD、SS的去除效果。结果表明:复合式竹丝填料生物反应器能有效去除化粪池出水中的COD和SS,平均去除率分别达到了85.4%和90%以上;复合式竹丝填料生物反应器的微生物数量较多、微生物链较长、微生物种群丰富;复合式竹丝填料生物反应器中的污泥增加量极少。将复合式竹丝填料生物反应器内的活性污泥和竹丝分开组成两个独立的生物反应器并处理化粪池污水,结果发现,竹丝生物膜反应器能在短期(18h)内超过活性污泥反应器的处理效果,且竹丝生物膜反应器的产泥量很低。可见,竹丝填料较为适合处理化粪池出水,是一种价格低廉、污染少、运行管理费用较低的良好填料。     

A/O-MBR处理生活污水回用的试验研究

采用缺氧-好氧一体式膜生物反应器(A/O-MBR)对生活污水处理回用进行了试验研究.试验结果表明,该系统具有较强的抗冲击负荷能力,膜分离截留对COD的去除起到了决定性作用,生物膜对NH3-N的去除占主要作用.系统出水无色无味,COD、NH3-N的浓度分别为14.82和0.45 mg/L,出水水质优于城市杂用水水质标准(GB/T 18920-2002)和河道景观环境用水水质标准(GB/T 18921-2002).     

间歇膨胀复合厌氧工艺用于处理抗生素废水

采用间歇膨胀复合厌氧/A-O-SBR工艺处理高浓度制药废水,在进水有机负荷为2.134～11.488 kgCOD/(m3.d)、pH值为4.5～6的常温条件下,厌氧反应器COD去除率>70%,容积负荷可达到9.075 kgCOD/(m3.d)。厌氧出水经A-O-SBR及混凝气浮处理后,出水COD、氨氮、总磷、pH值分别为130 mg/L、4.4 mg/L、2.39 mg/L、7.8,完全满足企业所在地的纳管排放要求。     

Halophilic biological treatment of tannery soak liquor in a sequencing batch reactor

Hypersaline wastewater (i.e. wastewater containing more than 35 gl(-1) total dissolved solids (TDS)) is generated by various industrial activities. This wastewater, rich in both organic matter and TDS, is difficult to treat using conventional biological wastewater treatment processes. Among the industries generating hypersaline effluents, tanneries are prominent in India. In this study, tannery wastewater from soak pit was treated in a lab-scale SBR for the removal of organic matter. The characterisation of the soak liquor showed that this effluent is biodegradable, though not easily, and highly variable, depending on the origin and the nature of the hides. TDS was in the range of 21-57 gl(-1) and COD was in the range of 1.5-3.6 gl(-1). This soak liquor was biologically treated in an aerobic sequencing batch reactor seeded with halophilic bacteria, and the performance of the system was evaluated under different operating conditions with changes in hydraulic retention time, organic loading rate and salt concentration. The changes in salinity appeared to affect the removal of organic matter more than the changes in hydraulic retention time or organic loading rate. Despite the variations in the characteristics of the soak liquor, the reactor achieved proper removal of organic matter, once the acclimation of the microorganisms was achieved. Optimum removal efficiencies of 95%, 93%, 96% and 92% on COD, PO4 3-, TKN and SS, respectively, could be reached with 5 days hydraulic retention time (HRT), an organic loading rate (OLR) of 0.6 kg COD m(-3)d(-1) and 34 g NaCl l(-1). The organisms responsible for nitrogen removal appeared to be the most sensitive to the modifications of these parameters.     

MBR对焚烧厂渗滤液中有机污染物的降解特性

采用膜生物反应器(MBR)处理垃圾焚烧厂渗滤液,并采用GC/MS技术考察了MBR处理渗滤液过程中有机污染物的降解特性.结果表明,生化段对C4～C8的有机物有较好的降解能力,而无机膜对C16～C19的有机物的去除效果较好;生化段对渗滤液中酸类有机物的降解效果明显,而无机膜对酮、醇、酸类有机物的去除效果明显;当进水COD为57 000 mg/L、NH3-N为665mg/L时,MBR出水的COD和NH3-N分别可降至457、8.54 mg/L.     

Application of a membrane bioreactor for treating explosives process wastewater

A bench-scale anoxic membrane bioreactor (MBR) system, consisting of a bioreactor coupled to a ceramic cross-flow ultrafiltration module, was evaluated to treat a synthetic wastewater containing alkaline hydrolysis byproducts (hydrolysates) of RDX. The wastewater was formulated the same as hydrolysis wastewater and consisted of acetate, formate and formaldehyde as carbon sources and nitrite and nitrate electron acceptors. The MBR system removed 80-90% of the carbon sources, and approximately 90% of the stoichiometric amount of nitrate, 60% of nitrite. The reactor was also operated over a range of transmembrane pressure, temperature, suspended solids concentration, and organic loading rate to maximize treatment efficiency and permeate flux. Increasing the transmembrane pressure and temperature did not improve flux significantly. Increasing mixed liquor volatile suspended solids (MLVSS) concentration in the bioreactor decreased the permeate flux significantly. The maximum volumetric organic loading rate was 0.72 kg COD/m3/day. The maximum food-to-mass ratio was 0.50 kg N/kg MLVSS/day and 1.82 kg COD/kg MLVSS/day. Membrane permeate was clear and essentially free of bacteria, as indicated by heterotrophic plate count. Permeate flux ranged between 0.15 and 2.0 m3/m2 day and was maintained by routine backwashing every three days. Backwashing with tap water containing chlorine bleach every fourth or fifth backwashing was able to restore membrane flux to its original value.     

Improving anaerobic sequencing batch reactor performance by modifying operational parameters.

A lab-scale anaerobic sequencing batch reactor (ASBR) that had operated with glucose at an organic loading rate of 2.1 kg COD m(-3) d(-1) was stressed with an organic loading rate of 3.2 kg COD m(-3) (-1). Five different combinations of influent concentration, total cycle time, and fill time to cycle time ratio were examined. No external pH control was used. In all cases, acetate and propionate were the main constituents of the effluent. Larger fill time to cycle time ratios and lower initial substrate concentrations resulted in improved performance suggesting that ASBR operation may be improved by changing operational parameters.     

环境温度下DASB预处理脱墨废水的研究

降流式厌氧污泥床反应器(DASB)作为一种新型厌氧处理工艺,具有生物截留能力强、泥水混合效果好、运行管理方便、性能可靠等优点。采用DASB对造纸脱墨废水进行预处理,研究了其影响因素和水解酸化效果。试验结果表明,pH值、HRT和容积负荷对DASB的运行效果有一定的影响,当出水pH值为7.0～7.2、HRT为22.4 h、容积负荷为2.15 kg/(m3.d)时,运行效果最好;在最佳运行条件下,当进水BOD5/COD值在0.38左右时,出水BOD5/COD值可提高到0.50左右,脱墨废水的可生化性大大提高。     

Performance of UASB reactor treating leachate from acidogenic fermenter in the two-phase anaerobic digestion of food waste

This study was conducted to investigate the performance of the upflow anaerobic sludge blanket (UASB) reactor treating leachate from acidogenic fermenter in the two-phase anaerobic digestion of food waste. The chemical oxygen demand (COD) removal efficiency was consistently over 96% up to the loading rates of 15.8 g COD/l d. The methane production rate increased to 5.51/l d. Of all the COD removed, 92% was converted to methane and the remaining presumably to biomass. At loading rates over 18.7 g COD/l d, the COD removal efficiency decreased due to sludge flotation and washout in the reactor, which resulted from short HRT of less than 10.6 h. The residual propionate concentration was the highest among the volatile fatty acids (VFA) in the effluent. The specific methanogenic activity (SMA) analysis showed that the VFA-degrading activity of granule was the highest for butyrate, and the lowest for propionate. Typical granules were found to be mainly composed of microcolonies of Methanosaeta. The size distribution of sludge particles indicated that partially granulated sludge could maintain the original structure of granular sludge and continue to gain size in the UASB reactor treating leachate from acidogenic fermenter.