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.     

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...     

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.     

Combined biologic (anaerobic-aerobic) and chemical treatment of starch industry wastewater

A combined biologic and chemical treatment of high-strength (total chemical oxygen demand [CODtot] up to 20 g/L), strong nitrogenous (total N up to 1 g/L), and phosphoric (total P up to 0.4 g/L) starch industry wastewater was investigated at laboratory-scale level. As a principal step for COD elimination, upflow anaerobic sludge bed reactor performance was investigated at 30 degrees C. Under hydraulic retention times (HRTs) of about 1 d, when the organic loading rates were higher than 15 g of COD/(L.d), the CODtot removal varied between 77 and 93%, giving effluents with a COD/N ratio of 4-5:1, approaching the requirements of subsequent denitrification. The activated sludge reactor operating in aerobic-anoxic regime (HRT of about 4 d, duration of aerobic and anoxic phases of 30 min each) was able to remove up to 90% of total nitrogen and up to 64% of COD tot from the anaerobic effluents under 17-20 degrees C. The coagulation experiments with Fe(III) showed that 1.4 mg of resting hardly biodegradable COD and 0.5 mg of phosphate (as P) could be removed from the aerobic effluents by each milligram of iron added.     

Anaerobic biological treatment of dye bearing water in anaerobic sequencing batch reactor: Performance and kinetics studies

Textile and dye industries are main sources of dye bearing effluent. In present studies the anaerobic biological degradation of Acid Red 3BN dye water (AR3BNDW) and mixed dye water (MDW) for reduction of color and COD were studied in sequential batch reactor (SBR). The sludge as sources of microorganism was arranged from maize processing bio methanation wastewater treatment plant, which was acclimatized for treatment of AR3BNDW and MDW. After the acclimatization, dyes degradation were studied in SBR At optimum operation condition of hydraulics retention time (HRT) = 2.5 d, and treatment time (t_R) = 16 h, AR3BNDW have gone maximum 87% color reduction of 500 mg/L dye, and 82.8% COD reduction of 380 mg/L COD. At same operating condition, 84.5% color reduction of 500 mg/L dye, and 79.42% COD reduction of 413 mg/L COD achieved for MDW. The second order Grau model was fitted well for COD and dye reductions. The kinetics parameter were evaluated for both the dye water.     

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.     

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.     

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.     

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.     

UF-两段厌氧处理茶多酚废水的研究

采用前置超滤膜(UF)的两相厌氧工艺对原水COD为18362.6mg/L,荼多酚为3608.3mg/L、色度为2624.2倍的茶多酚生产废水进行为期90d的实验研究.结果表明,当实验压力为0.2Mpa时,膜组件对COD去除率为63.4%,茶多酚去除率为95.1%,色度去除率为93.4%.然后,对两相厌氧工艺的投配率、P含量和酸化段水力停留时间(HRT1)对废水COD、色度与茶多酚去除率和产气率的影响进行了研究.当投配率为15.0%、P含量为38.1mg/L、HRT1=24h,该工艺达到最佳处理效果,出水COD为1288.1mg/L,COD去除率为80.8%,色度为95.6倍,色度去除率为44.6%,残余茶多酚为119.8mg/L,茶多酚去除率为32.3%,产气率为0.85m3/kg COD,与未采用UF预处理的两相厌氧水解工艺相比,COD、色度和荼多酚去除率分别提高23.40%,10.2%和1613%,产气率增加0.15m3/kg COD.     

Treatment of Sanitary Landfill Leachates in a Lab-Scale Gradual Concentric Chamber (GCC) Reactor

Sanitary landfill leachates are a major environmental problem in South American countries where sanitary landfills are still constructed and appropriate designs for the treatment of these leachates remain problematic. The performance of a lab-scale Gradual Concentric Chamber (GCC) reactor for leachates treatment is presented in this study. Two types of sanitary landfill residuals were evaluated, one directly collected from the garbage trucks (JGL), with high organic strength (84 g COD/l) and the second one, a 6-month-generated leachate (YL) collected from the lagoon of the sanitary landfill in Quito, Ecuador, with an organic strength of 66 g COD/l. Different operational parameters, such as organic loading rate (OLR), temperature, recycling and aeration, were tested. The GCC reactor was found to be a robust technology to treat these high-strength streams with organic matter removal efficiencies higher than 65%. The best performance of the reactors (COD removal efficiencies of 75–80%) was obtained at a Hydraulic Retention Time (HRT) of around 20 h and at 35 °C, with an applied OLR up to 70 and 100 g COD/l per day. Overall, the GCC reactor concept appears worth to be further developed for the treatment of leachates in low-income countries.     

Phospholipid/Polydiacetylene Vesicle-Based Colorimetric Assay for High-Throughput Screening of Bacteriocins and Halocins

Multi-phase anaerobic reactor for H₂ and CH₄ production from paperboard mill wastewater was studied. The reactor was operated at hydraulic retention times (HRTs) of 12, 18, 24, and 36 h, and organic loading rates (OLRs) of 2.2, 1.5, 1.1, and 0.75 kg chemical oxygen demand (COD)/m³ day, respectively. HRT of 12 h and OLR of 2.2 kg COD/m³ day provided maximum hydrogen yield of 42.76?±?14.5 ml/g COD_removed and volumetric substrate uptake rate (?rS) of 16.51?±?4.43 mg COD/L h. This corresponded to the highest soluble COD/total COD (SCOD/TCOD) ratio of 56.25?±?3.3 % and the maximum volatile fatty acid (VFA) yield (Y_VFA) of 0.21?±?0.03 g VFA/g COD, confirming that H₂ was mainly produced through SCOD conversion. The highest methane yield (18.78?±?3.8 ml/g COD_removed) and ?rS of 21.74?±?1.34 mgCOD/L h were achieved at an HRT of 36 h and OLR of 0.75 kg COD/m³ day. The maximum hydrogen production rate (HPR) and methane production rate (MPR) were achieved at carbon to nitrogen (C/N) ratio of 47.9 and 14.3, respectively. This implies the important effect of C/N ratio on the distinction between the dominant microorganism bioactivities responsible for H₂ and CH₄ production.     

Electricity production by a microbial fuel cell fueled by brewery wastewater and the factors in its membrane deterioration

Electricity production from brewery wastewater using dual-chamber microbial fuel cells (MFCs) with a tin-coated copper mesh in the anode was investigated by changing the hydraulic retention time (HRT). The MFCs were fed with wastewater samples from the inlet (inflow, MFC-1) and outlet (outflow, MFC-2) of an anaerobic digester of a brewery wastewater treatment plant. Both chemical oxygen demand removal and current density were improved by decreasing HRT. The best MFC performance was with an HRT of 0.5 d. The maximum power densities of 8.001 and 1.843 μW/cm2 were obtained from reactors MFC-1 and MFC-2, respectively. Microbial diversity at different condi-tions was studied using PCR-DGGE profiling of 16S rRNA fragments of the microorganisms from the biofilm on the anode electrode. The MFC reactor had mainlyGeobacter,Shewanella, andClostridium species, and some bacteria were easily washed out at lower HRTs. The fouling characteristics of the MFC Nafion membrane and the resulting degradation of MFC performance were examined. The ion exchange capacity, conductivity, and diffusivity of the membrane decreased significantly after foul-ing. The morphology of the Nafion membrane and MFC degradation were studied using scanning electron microscopy and attenuated total reflection-Fourier transform infrared spectroscopy.     

Feasibility of 2,4,6-Trichlorophenol and Malonic Acid as Metabolic Uncoupler for Sludge Reduction in the Sequence Batch Reactor for Treating Organic Wastewater

The activated sludge process generates a large amount of excess sludge as a byproduct, which is one of the most serious challenges in biological wastewater treatment. In the present study, the feasibility of 2,4,6-trichlorophenol (TCP) and malonic acid (MA) as metabolic uncouplers to reduce sludge generation in the sequence batch reactor (SBR) for treating organic wastewater for a long period was studied. The results showed that 2 mg/L TCP could reduce sludge generation by about 47%, while chemical oxygen demand (COD) removal efficiency and sludge settlability were not obviously influenced. Although 10 mg/L MA could also reduce excess sludge production by about 30% while slightly affecting COD removal, it seriously deteriorated sludge settlability. Accordingly, TCP is a better uncoupler for sludge reduction for a longer period in the SBR for treating organic wastewater, and MA can only be used as a short-term or transitional uncoupler. Microscopic and 16S ribosomal deoxyribonucleic acid analyses showed that the microbial population of sludge varied when uncouplers were fed to the activated sludge system. Occurrence of large amounts of filament and the disappearance of protozoa may be the main reason for the aggravation of sludge settlability under uncoupled metabolic conditions caused by MA.     

Biodegradability enhancement of textile wastewater by electron beam irradiation

Textile wastewater generally contains various pollutants, which can cause problems during biological treatment. Electron beam radiation technology was applied to enhance the biodegradability of textile wastewater for an activated sludge process. The biodegradability (BOD₅/COD) increased at a 1.0 kGy dose. The biorefractory organic compounds were converted into more easily biodegradable compounds such as organic acids having lower molecular weights. In spite of the short hydraulic retention time (HRT) of the activated sludge process, not only high organic removal efficiencies, but also high microbial activities were achieved. In conclusion, textile wastewater was effectively treated by the combined process of electron beam radiation and an activated sludge process.     

The Effect of Biomass Immobilization Support Material and Bed Porosity on Hydrogen Production in an Upflow Anaerobic Packed-Bed Bioreactor

The aim of this study was to investigate the effect of the support material used for biomass attachment and bed porosity on the potential generation of hydrogen gas in an anaerobic bioreactor treating low-strength wastewater. For this purpose, an upflow anaerobic packed-bed (UAPB) reactor fed with sucrose-based synthetic wastewater was used. Three reactors with various support materials (expanded clay, vegetal coal, and low-density polyethylene) were operated for hydraulic retention time (HRT) of 0.5 and 2 h. Based on the results obtained, three further reactors were operated with low-density polyethylene as a material support using various bed porosities (91, 75, and 50 %) for an HRT of 0.5 h. The UAPB reactor was found to be a feasible technology for hydrogen production, reaching a maximum substrate-based hydrogen yield of 7 mol H₂ mol^?1 sucrose for an HRT of 0.5 h. The type of support material used did not affect hydrogen production or the microbial population inside the reactor. Increasing the bed porosity to 91 % provided a continuous and cyclic production of hydrogen, whereas the lower bed porosities resulted in a reduced time of hydrogen production due to biomass accumulation, which resulted in a decreasing working volume.     

Treatment options for tannery wastewater II: integrated chemical and biological oxidation

This is the second of two papers each dealing with a specific technological option for replacing the Fenton's reagent with simpler processes for treating industrial wastewater. In particular, the paper reports the results of an investigation aimed to check, at lab scale, the effectiveness of an alternative wastewater treatment combining biological degradation and chemical oxidation with ozone. The treatment was carried out in a lab scale hybrid reactor fed with the biological stage effluent of a plant treating the wastewater of a large tanning district in Central Italy whose residual COD result still higher than the Italian COD Maximum Allowable Concentration (MAC) value (i.e., 160 mgO2/L) The results are very promising, considering that a removal efficiency of 41% (as COD) has been achieved by treating an influent characterized by a COD content fully biorefractory. In addition, the proposed treatment presents the significant advantage of no additional sludge production, as happens with commonly utilized tertiary processes (i.e. Fenton), that is characterized by high chemical sludge production.     

Single-stage anaerobic codigestion for mixture wastes of simulated Korean food waste and waste activated sludge

Korean food waste was treated with a single-stage anaerobic codigester (SSAD) using waste activated sludge (WAS) generated from a municipal wastewater treatment plant. The stability and performance of the system was analyzed. The C/N ratio was improved with increasing food waste fraction of feed mixture. The pH, alkalinity, and free ammonia nitrogen concentration were the parameters used to evaluate the digester’s stability. The experimentally determined values of the parameters indicated that there were no methane inhibitions in the digester. Digester performance was determined by measuring the total chemical oxygen demand TCOD), volate solids (VS) removal, methane content in biogas, methane production rate (MPR), and specific methane productivity. Methane content in biogas and MPR were significantly dependent on hydraulic retention time (HRT) and ratio of food waste to WAS. The methane content in biogas decreased at shorter HRT or higher organic loading rate (OLR) with increased food waste fraction. Concerning the performance of the codigester, the optimum operating condition of the SSAD was found to be at an HRT of 10 d with a feed mixture ratio of 50% food waste and 50% WAS. A TCOD removal efficiency of 53.6% and a VS removal efficiency of 53.7% were obtained at an OLR of 5.96 kg of TCOD/(m³·d) and 3.14 kg of VS/(m³·d), respectively. A maximum MPR of 1.15 m³ CH₄/(m³·d) and an SMP of 0.37 m³ CH₄/kg of VS_feed were obtained at an HRT of 10 d with a methane content of 63%.     

The performance and degradation mechanism of sulfamethazine from wastewater using IFAS-MBR

Sulfamethazine(SMZ) is an important sulfonamide antibiotic.Although the concentration in the environment is small,it is harmful.The drug residues can be transferred,transformed or accumulated,affecting the growth of animals and plants.In this study,the integrated fixed-film activated sludge membrane bioreactor(IFAS-MB R) were constructed to investigate the performance and degradation mechanism of SMZ.The addition of SMZ had a significant impact on the removal of the chemical oxygen demand(COD) and ammonia nitrogen(NH_4^+-N).The optimal operating conditions were hydraulic retention time(HRT) at 10 h and solid retention time(SRT) at 80 d,respectively.On this basis,the effects of different SMZ concentrations on nutrient removal,degradation,and sludge characteristics were compared.The removal efficiency of SMZ increased with the increase of SMZ concentration.The maximum removal rate was as high as 87%.The SMZ dosage also had an obvious effect on sludge characteristics.As the SMZ concentration increased,the extracellular polymer substances(EPS) concentration and the membrane resistance both decreased,which were beneficial for the reduction of membrane fouling.Finally,seven kinds of SMZ biodegradation intermediates were identified,and the possible degradation pathways were speculated.The microbial community results showed that the microbial diversity and richness in the reactor decreased after adding SMZ to the influent.The relative abundance of Bacteroidetes,Actinobacteria,Saccharibacteria and Nitro spirae increased at the phylum level.Sphingobacteria and Betaproteobacteria became dominant species at the class level.The relative abundance of norankp-Saccharibacteria and Nitrospirae increased significantly,and norank-p-Saccharibacteria may be the dominant bacteria for SMZ degradation.     

Co-Fermentation of Cheese Whey and Crude Glycerol in EGSB Reactor as a Strategy to Enhance Continuous Hydrogen and Propionic Acid Production

This study evaluated the production of hydrogen and propionic acid in an expanded granular sludge bed (EGSB) reactor by co-fermentation of cheese whey (CW) and crude glycerol (CG). The reactor was operated at hydraulic retention time (HRT) of 8 h by changing the CW/CG ratio from 5:1 to 5:2, 5:3, 5:4, and 5:5. At the ratio of 5:5, HRT was reduced from 8 to 0.5 h. The maximum hydrogen yield of 0.120 mmol H₂ g COD^?1 was observed at the CW/CG ratio of 5:1. Increasing the CG concentration repressed hydrogen production in favor of propionic acid, with a maximum yield of 6.19 mmol HPr g COD^?1 at the CW/CG ratio of 5:3. Moreover, by reducing HRT of 8 to 0.5 h, the hydrogen production rate was increased to a maximum value of 42.5 mL H₂ h^?1 L^?1at HRT of 0.5 h. The major metabolites were propionate, 1,3-propanediol, acetate, butyrate, and lactate.