One- and two-stage upflow anaerobic sludge-bed reactor pretreatment of winery wastewater at 4–10°C

The operating performance of a single and two (in series) laboratory upflow anaerobic sludge-bed (UASB) reactors (2.7-L working volume, recycle ratio varied from 1:1 to 1:18) treating diluted wine vinasse was investigated under psychrophilic conditions (4-10 degreesC). For a single UASB reactor seeded with granular sludge, the average organic loading rates (OLRs) applied were 4.7, 3.7, and 1.7 g of chemical oxygen demand (COD)/(L.d) (hydraulic retention times [HRTs] were about 1 d) at 9-11, 6 to 7, and 4 to 5 degreesC, respectively. The average total COD removal for preacidified vinasse wastewater was about 60% for all the temperature regimes tested. For two UASB reactors in series, the average total COD removal for treatment of non-preacidified wastewater exceeded 70% (the average OLRs for a whole system were 2.2, 1.8, and 1.3 g of COD/[L.d] under HRTs of 2 d at 10, 7, and 4 degreesC, respectively). In situ determinations of kinetic sludge characteristics (apparent Vm and Km) revealed the existence of substantial mass transfer limitations for the soluble substrates inside the reactor sludge bed. Therefore, application of higher recycle ratios is essential for enhancement of UASB pretreatment under psychrophilic conditions. The produced anaerobic effluents were shown to be efficiently posttreated aerobically: final effluent COD concentrations were about 0.1 g/L. Successful operation of the UASB reactors at quite low temperatures (4-10 degreesC) opens some perspectives for application of high-rate anaerobic pretreatment at ambient temperatures.     

Role of Vitamins B-3 and C in the Fashioning of Granules in UASB Reactor Sludge

Whereas a myriad of possible factors have been reported which effect the formation of granules in a upflow anaerobic sludge blanket (UASB) reactor and influence their properties, there is no study on the effect of vitamins on the granulation of UASB reactor sludge. The present study was undertaken to bridge this gap. It was seen that vitamins helped in better granule formation??as reflected by favorable size distribution, sludge volume index, and settling velocity??compared to controls. The vitamin-spiked reactors also achieved >85?% COD removal efficiency in half the number of days the unspiked reactors took. The vitamin supplements were effective at concentrations????1?mg/l. Hence, their use in expediting granule formation as also in developing better-quality granules appears economically viable.     

Removal of chemical oxygen demand,nitrogen, and heavy metals using a sequenced anaerobic-aerobic treatment of landfill leachates at 10-30 degrees C

As a first step of treatment of landfill leachates (total chemical oxygen demand [COD]: 1.43–3.81 g/L; total nitrogen: 90–162 mg/L), performance of laboratory upflow anaerobic sludge bed reactors was investigated under mesophilic (30°C), submesophilic (20°C), and psychrophilic (10°C) conditions. Under hydraulic retention times (HRTs) of about 0.3 d, when the average organic loading rates (OLRs) were about 5 g of COD/(L·d), the total COD removal accounted for 81% (on average) with the effluent concentrations close to the anaerobic biodegradability limit (0.25 g of COD/L) for mesophilic and submesophilic regimes. The psychrophilic treatment conducted under an average HRT of 0.34 d and an average OLR of 4.22 g of ducted under an average HRT of 0.34 d and an average OLR of 4.22 g of COD/(L·d) showed a total COD removal of 47%, giving effluents (0.75 g of COD/L) more suitable for subsequent biologic nitrogen removal. All three anaerobic regimes used for leachate treatment were quite efficient for elimination of heavy metals (Fe, Zn, Cu, Pb, Cd) by concomitant precipitation in the form of insoluble sulfides inside the sludge bed. The application of aerobic/anoxic biofilter as a sole polishing step for psychrophilic anaerobic effluents was acceptable for elimination of biodegradable COD and nitrogen approaching the current standards for direct discharge of treated waste-water.     

Combining mixing regimes for optimized anaerobic wastewater treatment

Operational practice of high-rate anaerobic bioreactors such as upflow anaerobic sludge bed (UASB) reactors is generally based on maximization of the biomass concentration and, in the case of more than one reactor compartment, operation in parallel. In this article, a modeling approach is used to postulate that the treatment performance of anaerobic bioreactors can be improved by simple operational measures. To achieve minimized effluent soluble substrate concentrations, operation of two reactors in series combined with active exchange of biomass between both reactors is suggested. In this way, substrate concentrations lower than the minimum achievable concentration in a completely mixed reactor can be achieved. It is furthermore suggested that maximized biomass concentrations (and solid retention times [SRTs]) do not necessarily lead to minimized effluent concentrations of organic material. At elevated SRTs, the soluble microbial products resulting from biomass turnover are shown to represent the main fraction of soluble organic material in the effluent of the reactor, limiting treatment efficiency.     

Anaerobic Digestion of Sugarcane Vinasse Through a Methanogenic UASB Reactor Followed by a Packed Bed Reactor

The anaerobic treatment of raw vinasse in a combined system consisting in two methanogenic reactors, up-flow anaerobic sludge blanket (UASB) + anaerobic packed bed reactors (APBR), was evaluated. The organic loading rate (OLR) was varied, and the best condition for the combined system was 12.5 kg COD m^?3day^?1 with averages of 0.289 m³ CH₄ kg COD r^?1for the UASB reactor and 4.4 kg COD m^?3day^?1 with 0.207 m³ CH₄ kg COD r^?1 for APBR. The OLR played a major role in the emission of H₂S conducting to relatively stable quality of biogas emitted from the APBR, with H₂S concentrations <10 mg L^?1. The importance of the sulphate to COD ratio was demonstrated as a result of the low biogas quality recorded at the lowest ratio. It was possible to develop a proper anaerobic digestion of raw vinasse through the combined system with COD removal efficiency of 86.7% and higher CH₄ and a lower H₂S content in biogas.     

Electron beam pretreatment of sewage sludge before anaerobic digestion

The pretreatment of waste-activated sludge (WAS) by electron beam irradiation was studied in order to improve anaerobic sludge digestion. The irradiation dose of the electron beam was varied from 0.5 to 10 kGy. Batch and continuous-flow stirred tank reactors (CFSTRs) were operated to evaluate the effect of the electron beam pretreatment on anaerobic sludge digestion. Approximately 30–52% of the total chemical oxygen demand (COD) content of the WAS was solubilized within 24 h after electron beam irradiation. A large quantity of soluble COD, protein, and carbohydrates leached out from cell ruptures caused by the electron beam irradiation. Volatile fatty acids production from the irradiated sludge was approx 90% higher than that of the unirradiated sludge. The degradation of irradiated sewage sludge was described by two distinct first-order decay rates (k ₁ and k ₂). Most initial decay reaction accelerated within 10 d, with an average k ₁ of 0.06/d for sewage sludge irradiated at all dosages. The mean values for the long-term batch first-order decay coefficient (k ₂) were 0.025/d for irradiated sewage sludge and 0.007/d for unirradiated sludge. Volatile solids removal efficiency of the control reactor fed with unirradiated sewage sludge at a hydraulic retention time (HRT) of 20 d was almost the same as that of the CFSTRs fed with irradiated sludge at an HRT of 10 d. Therefore, disintegration of sewage sludge cells using electron beam pretreatment could reduce the reactor solid retention time by half.     

厌氧悬浮填料生物膜反应器处理费托合成废水

采用厌氧悬浮填料生物膜反应器工艺对费托合成废水进行处理,考察了高有机负荷条件下系统的运行情况.有机负荷小于31.1g/(L·d)时,COD去除率达97%以上;当有机负荷从39.7g/(L·d)增加至56.3g/(L·d)时,厌氧反应对COD的去除率从88%降至6l%.实验结果表明,填料生物膜比悬浮污泥具有更高的活性,M...     

Anaerobic treatment of low-strength brewery wastewater in expanded granular sludge bed reactor

Anaerobic treatment of low-strength brewery wastewater, with influent total chemical oxygen demand (COD) (CODin) concentrations ranging from 550 to 825 mg/L, was investigated in a pilot-scale 225.5-L expanded granular sludge bed (EGSB) reactor. In an experiment in which the temperature was lowered stepwise from 30 to 12 degrees C, the COD removal efficiency decreased from 73 to 35%, at organic loading rates (OLR) of 11-16.5 g COD/L/d. The applied hydraulic retention time (HRT) and liquid upflow velocity (Vup) were 1.2 h and 5.8 m/h, respectively. Under these conditions, the acidified fraction of the CODin varied from 45 to 90%. In addition to the expected drop in reactor performance, problems with sludge retention were also observed. In a subsequent experiment set at 20 degrees C, COD removal efficiencies exceeding 80% were obtained at an OLR up to 12.6 g COD/L/d, with CODin between 630 and 715 mg/L. The values of HRT and Vup applied were 2.1-1.2 h, and 4.4-7.2 m/h, respectively. The acidified fraction of the CODin was above 90%, but sludge washout was not significant. These results indicate that the EGSB potentials can be further explored for the anaerobic treatment of low-strength brewery wastewater, even at lower temperatures.     

Treatment of sewage sludge generated in municipal wastewater treatment plants

This study was designed to evaluate the performance of a cylindrical anaerobic digester in treating secondary sewage sludge. A series of three independent batch experiments was performed for a total operation time of 60 d. The system of anaerobic digestion showed stability conditions, with no noticeable scum or foaming problems. The chemical oxygen demand reduction reached 29, 21, and 45% in sludge and 95, 85, and 82% in supernatant for the three experiments, respectively. Total coliform bacteria levels in the digester ranged from 10⁴ to 10⁵ in influent sludge and from 10⁴ to 10³ in effluent sludge, with an average reduction of 90%. Fecal coliforms of the order of 10⁴ were enumerated in influent sludge and those of the order of 10⁰ were enumerated in effluent sludge, with an average reduction of 99.9%. The studied system had satisfactory results, showing that both organic matter and indicator bacteria levels substantially decrease when the sludge is submitted to anaerobic digestion.     

The anaerobic treatment of soft drink wastewater in UASB and hybrid reactors

The anaerobic treatment of soft drink wastewater (SDW) was studied in two laboratory reactors—a 1.8-L UASB reactor and a 3-L hybrid reactor-sludge bed containing a layer of polyurethane in the upper part, at 35°C. The highest organic loading rates (OLR) achieved were 13 and 16.5 g COD/L · D for hybrid and UASB reactors, respectively, with the treatment efficiency of about 80% for both reactors. Despite the higher treatment productivity achieved for the UASB reactor, its lower ability to generate a sufficient level of alkalinity led to difficulties in maintaining a stable operation performance. Therefore, the hybrid reactor seems to be indicated for OLR higher than 10 g COD/L · d and HRT lower than 1 D, from the point of view of reliability of these two systems. Both reactors can treat the SDW with pH influent up to 11.0. The feeding of reactors with higher pH influent values led to their quick failure because of alkali shock. The duration of the recovery period after alkali shock was about 1.5-2 mo.     

Sequential anaerobic/aerobic treatment of dye-containing wastewaters: colour and COD removals, and ecotoxicity tests

Colour and COD removals of the azo dyes Congo Red (CR) and Reactive Black 5 (RB5) were individually evaluated in a sequential anaerobic/aerobic treatment system. Additionally, dye toxicity was assessed by using acute ecotoxicity tests with Daphnia magna as the indicator-organism. The anaerobic reactor was operated at approximately 27 °C and with hydraulic retention times of 12 and 24 h. The aerobic reactor was operated in batch mode with a total cycle of 24 h. During anaerobic step, high colour removals were obtained, 96.3% for CR (400 mg/L) and 75% for RB5 (200 mg/L). During the aerobic phase, COD effluent was considerably reduced, with an average removal efficiency of 52% for CR and 85% for RB5, which resulted in an overall COD removal of 88% for both dyes. Ecotoxicity tests with CR revealed that the anaerobic effluent presented a higher toxicity compared with the influent, and an aerobic post-treatment was not efficient in reducing toxicity. However, the results with RB5 showed that both anaerobic and aerobic steps could decrease dye toxicity, especially the aerobic phase, which removed completely the toxicity in D. magna. Therefore, the anaerobic/aerobic treatment is not always effective in detoxifying dye-containing wastewaters, sometimes even increasing dye toxicity.     

Energy generation by methanation of persistent wastes

A 15-L anaerobic fixed-film reactor (AFFR) was evaluated for treating a trade effluent containing inhibitory concentrations of persistent branched-chain fatty acids, namely 2-ethylhexanoic acid (2-EHA) and neopentanoic acid (NPA), at a total of 17,000 mg COD/L. The AFFR was packed with fire-expanded clay spheres, and start-up was accomplished in 60 d. The organic load was increased in steps from 1.1 to 8.5 g COD/L/d. Total COD, 2-EHA, and NPA removal efficiencies were maintained above 70, 98, and 75%, respectively. The reactor could recover from a shock load of 150% increase in organic load. Combined mechanisms of organic adsorption and biodegradation rendered the AFFR more stable with shock loads. Mathane gas produced from the process could be used for preheating the effluent.     

Pretreatment of swine wastewater using anaerobic filter

Efforts were made to assess the efficiency of an anaerobic filter packed with porous floating ceramic media and to identify the optimum operational condition of anaerobic filter as a pretreatment of swine wastewater for the subsequent biological removal of nitrogen and phosphorus. A stepwise decrease in hydraulic retention time (HRT) and an increase in organic loading rate (OLR) were utilized in an anaerobic filter reactor at mesophilic temperature (35°C). The optimum operating condition of the anaerobic filter was found to be at an HRT of 1 d. A soluble chemical oxygen demand (COD) removal efficiency of 62% and a total suspended solids removal efficiency of 39% at an HRT of 1 d were achieved with an OLR of 16.0 kg total COD/(m³·d), respectively. The maximum methane production rate approached 1.70 vol of biogas produced per volume of reactor per day at an HRT of 1 d. It was likely that the effluent COD/total Kjeldahl nitrogen ratio, of 22, the COD/total phosphorous ratio of 47, and the high effluent alkalinity >2500 mg/L as CaCO₃ of the anaerobic filter operated at an HRT of 1 d was adequate for the subsequent biological removal of nitrogen and phosphorus.     

Mixed- and plug-flow performances of an anaerobic biofilter treating 2-ethylhexanoic acid

The performance of a 20-L anaerobic biofilter treating 2-ethyl-hexanoic acid (2-EHA) operating with the effluent recirculated was compared with that of the same biofilter operated without any recirculation. The recirculation of effluent was at a rate of 60 L/h through the biofilter. Tracer experiments were carried out to study the hydrodynamics in the biofilter under different modes of operation. The dispersion number (D/UL) obtained from these tracer experiments for the biofilter operated with and without effluent recirculation were 0.65 and 0.06, respectively. These values show that the recirculation was effective in achieving a mixed-flow pattern in the biofilter, whereas the biofilter operated without recirculation was essentially a plug-flow column with a moderate level of axial dispersion. The feed consisted of 2-EHA at a concentration of 8200 mg/L, which is equivalent to a COD of 20,000 mg/L. The optimal performance of the mixed-flow biofilter was at a hydraulic retention time (HRT) of 1.1 d, with a COD removal efficiency of 92.8% and a biogas production rate of 6.44 L/L biofilter vol/d. The biofilter failed at 0.83 d HRT, as a result of washout of biomass at this high hydraulic loading rate. By comparison, the optimal performance achieved for the plug-flow system was at 2 d HRT. The COD removal efficiency was 74.1%, and biogas production rate was 2.13 L/L biofilter vol/d. When the HRT was lowered to 1.5 d, failure occurred owing to inhibition as indicated by the low methane yield of 0.192 L/g COD removed. The superior performance of the mixed-flow mode can be attributed to the presence of the recycle stream, which diluted and evenly distributed the feed.     

Sustainable treatment and reuse of diluted pig manure streams in Russia: from laboratory trials to full-scale implementation

This article summarizes the results obtained during the laboratory and pilot development of integrated biologic and physicochemical treatment and reuse of diluted pig manure streams. The application of a straw filter was an effective means to separate the solid and liquid fractions of raw wastewater and resulted in the removal of a significant part of the dry matter, total nitrogen, and phosphorus (65, 27, and 32%, respectively). From the filtrate generated, 60–80% of the total chemical oxygen demand (COD) was removed in an upflow anaerobic sludge bed reactor operating at 15–30°C. Ammonia was efficiently eliminated (>99%) from the anaerobic effluents using Ural laumantite as an ion exchanger. However, the nitrogen-content of the zeolite was too low to consider this method of ammonia removal economically feasible. The phosphate precipitation block, consisting of stripper of CO₂ and fluidized-bed crystallizator, was able to decrease the concentration of soluble phosphate in the anaerobic effluents up to 7–15 mg of phosphate/L. The application of aerobic/anoxic biofilter as a sole polishing step was acceptable from an aesthetic point of view (the effluents were transparent and almost colorless and odorless) and elimination of biochemical oxygen demand (the resting COD was hardly biodegradable). However, the effluent nutrient concentrations (especially nitrogen) were far from the current standards for direct discharge of treated wastewater. We discuss the approaches for further improvement of effluent quality. Finally, we provide an outline of a full-scale system that partially implements the laboratory- and pilot-scale results obtained.     

Treatment of coke plant wastewater by A/O fixed biofilm system

The long-term environmental impacts of wastewa-ter from coke plant can be very high, especially due to the discharge of large amounts of wastewater. The composition of coke plant wastewater is complicated and varies from one factory to another, depending …     

葡萄糖乙酸钠不同基质微生物燃料电池电化学性能对比研究

本文通过接种生活污水处理厂的好氧污泥和厌氧污泥,撘建两个双室微生物燃料电池(MFC,Microbial fuel cell),分别以葡萄糖、乙酸钠作为基质,在0.0335 mol•L^-1基质浓度下研究不同基质微生物燃料电池的产电性能. 研究表明：葡萄糖体系的阳极半电池阻抗为222 Ω,乙酸钠体系为213.67 Ω,说明两种不同有机基质对电池内阻无明显影响. 葡萄糖、乙酸钠体系的交换电流密度i⁰分别为3.463 mA•m^-2、 5.987mA•m^-2;COD去除率分别为50.6%、55.8%;库仑效率分别为42.1%、46.2%. 葡萄糖为基质时最大输出功率密度为394.2 mW•m^-2,相应的最大电流密度为1800mA•m^-2;乙酸钠为基质时最大输出功率密度为311.9mW•m^-2,相应的最大电流密度为1527.5mA•m^-2. 葡萄糖代谢过程复杂并不单一,且代谢不彻底,乙酸钠分子简单更容易代谢,因此乙酸钠的库伦效率及COD去除率均高于葡萄糖,由以上数据可以得出葡萄糖为基质的燃料电池产电性能较好.     

The preparation of an adsorbent from mixtures of sewage sludge and coal-tar pitch using an alkaline hydroxide activation agent

The increasing generation of sewage sludge and its subsequent treatment are very sensitive environmental problems. For the more stable and sanitary treatment of this sewage sludge, there have been many studies, including the recent attempt to prepare an adsorbent from sewage sludge via recycling. In this study, of the adsorbent preparation methods, chemical activation was utilized, and in order to find the optimum conditions, several variables were tested, such as the activation agent concentration, activation temperature and activation time. The activation agents used in this study were alkaline hydroxides: KOH and NaOH. The properties of prepared adsorbent were also measured by analyzing the iodine adsorptivity and surface area. In addition, the prepared adsorbent, the BOD, COD, SS, T-N and T-P removal efficiencies from the effluent water of a sewage treatment plant were examined via column test. From the test, the optimum conditions for KOH-activation were 1 mol/l, 800 °C and 1.5 h for the activation agent concentration, activation temperature and activation time, respectively; whereas those for NaOH-activation were 1.25 mol/l, 850 °C and 1.5 h. From the application of the prepared adsorbent to the effluent water of the sewage treatment plant, the measured BOD, COD, SS, T-N and T-P removal efficiencies, the P1-800 adsorbent had the highest efficiencies for BOD, COD and SS of 56.68, 57.76 and 81.45%, respectively.     

不同饥饿时间下稳态好氧颗粒污泥系统的特性和动力学分析

较长的饥饿时间是好氧颗粒污泥驯化形成的关键条件. 但在稳态颗粒污泥系统中, 饥饿时间长短对颗粒污泥的影响还不清楚. 因此本实验采用四个序批式反应器(SBR), 分别在好氧饥饿时间为1、2、3和4 h(R1~R4)条件下运行, 研究了饥饿时间对稳态好氧颗粒污泥系统的运行和特性等方面的影响. 结果表明: 对于稳态的好氧颗粒污泥系统, 较长饥饿时间已不是保持污泥颗粒化的关键因素, 系统在饥饿时间缩短后依然会保持污泥颗粒化和稳定运行效果. 四种饥饿时间条件下反应器中COD去除效果没有表现出明显差异, COD平均去除率都几乎为98%以上. 但在不同饥饿时间条件下, 好氧颗粒污泥的性质有很大差别. 在 35天实验运行中, 与较长饥饿时间相比, 饥饿时间的缩短会使污泥中胞外聚合物含量降 低, 但PN/PS值会提高约6%左右, 好氧颗粒直径增大. 同时, 当饥饿时间大于2 h会使颗粒污泥中丝状菌过度生长, SVI30值升高约1.5倍, 并且导致颗粒的物理性质降低. 但是, 动力学分析指出R1~R4的有机污染物降解速率在0.25~0.29 h^-1之间, 较短饥饿时间的系统虽具有较高的qmax值, 可是并不明显. 并且R1~R4系统的饱和常数(K)和产率系数(Y)分别在5.39~8.45 mg/L和 0.391~0.746 kgMLVSS/kgCOD, 较短饥饿时间的系统会具有较高的COD出水浓度和剩余污泥产率. 综上, 好氧颗粒污泥驯化成功后, 稳态的颗粒污泥系统不再需要在较长饥饿时间条件下运行, 可以适当缩短反应时间, 这不仅仅可以节约运行成本, 降低不必要的能源消耗, 还可以使系统具有较高的稳定性能.     

Fermentative Hydrogen Production from Soybean Protein Processing Wastewater in an Anaerobic Baffled Reactor (ABR) Using Anaerobic Mixed Consortia

Fermentative H(2) production from soybean protein processing wastewater (SPPW) was investigated in a four-compartment anaerobic baffled reactor (ABR) using anaerobic mixed cultures under continuous flow condition in the present study. After being inoculated with aerobic activated sludge and operated at the inoculants of 5.98?gVSS?L(-1), COD of 5000?mg?L(-1), HRT of 16?h and temperature of (35?±?1) °C for 22?days, the ABR achieved stable ethanol-type fermentation. The specific hydrogen production rate of anaerobic activated sludge was 165?LH(2)?kg MLVSS(-1)?day(-1), the substrate conversion rate was 600.83?LH(2)?kg COD(-1)and the COD removal efficiency was 44.73% at the stable operation status. The ABR system exhibited a better stability and higher hydrogen yields than continuous stirring tank reactor under the same operational condition. The experimental data documented the feasibility of substrate degradation along with molecular H(2) generation utilizing SPPW as primary carbon source in the ABR system.