UASB法在啤酒厂废水处理中的应用

根据国内啤酒废水的水质特点,运用UASB法处理啤酒厂废水,此方法可将原废水COD值（800mg／L-3000mg／L）降低到国家规定的排放标准（≤500mg／L）,将此工艺与水解酸化池联合,可提高处理效率。     

Mechanisms and models for anaerobic granulation in upflow anaerobic sludge blanket reactor

Upflow anaerobic sludge blanket (UASB) reactor has been employed in industrial and municipal wastewater treatment for decades. However, the long start-up period required for the development of anaerobic granules seriously limits the application of this technology. In order to develop the strategy for rapid UASB start-up, the mechanisms for anaerobic granulation should be understood. This paper attempts to provide a up-to-date review on the existing mechanisms and models for anaerobic granulation in the UASB reactor, which include inert nuclei model, selection pressure model, multi-valence positive ion-bonding model, synthetic and natural polymer-bonding model, Capetown's model, spaghetti theory, syntrophic microcolony model, multi-layer model, secondary minimum adhesion model, local dehydration and hydrophobic interaction model, surface tension model, proton translocation-dehydration theory, cellular automaton model and cell-to-cell communication model. Based on those previous works, a general model for anaerobic granulation is also proposed. It is expected that this paper would be helpful for researchers to further develop a unified theory for anaerobic granulation and technology for expediting the formation of the UASB granules.     

Characterization of microbial community in granular sludge treating brewery wastewater

The diversity and distribution of microbes within brewery-degrading anaerobic sludge granules were studied using various molecular techniques. Molecular cloning of small-subunit rRNA gene sequences indicated that all archaeal clones were affiliated with Methanosaeta concillii (>99% sequence similarity), and the bacterial clones were mostly affiliated with a not-yet-cultured Clostridium cluster (48 out of 99 clones) in the low G + C gram-positive group, Xanthomonas spp. in the gamma-subclass of Proteobacteria (30 clones), and Desulfovibrio spp. (16 clones) in the delta-subclass of Proteobacteria. Slot-blot hybridization indicated that archaeal cells from the Methanomicrobiales (58.4% of total rRNA), Methanobacterials (3.3%) and Methanococcales (1.0%) accounted for 62.4% of the total community rRNA. The rest of the microbial populations were the clostridial cluster (27.3% of total rRNA) and Desulfovibrio spp. (9.4%). Fluorescence in-situ hybridization with domain and group-specific oligonucleotide probes further revealed a multi-layer granular architecture. On the surface layer, the hydrolytic clostridial species and hydrogenotrophic Methanobacteriales were the predominant. In the middle layer, mostly H2-producing acetogens from the delta-Proteobacteria (i.e., Desulfovibrio spp.), hydrogenotrophic Methanobacteriales and aceticlastic Methanosaeta were observed to presumably form a syntrophic association. Finally, the center core consisted of microcolonies of Methanosaeta cells.     

UASB-SBR工艺处理玉米淀粉生产废水

介绍了玉米淀粉废水的特点，阐述了UASB-SBR工艺处理玉米淀粉废水的工艺流程，经工程实际运行表明，可稳定达到国家二级排放标准，同时获得了显著的经济效益。     

Integrated application of upflow anaerobic sludge blanket reactor for the treatment of wastewaters

The UASB process among other treatment methods has been recognized as a core method of an advanced technology for environmental protection. This paper highlights the treatment of seven types of wastewaters i.e. palm oil mill effluent (POME), distillery wastewater, slaughterhouse wastewater, piggery wastewater, dairy wastewater, fishery wastewater and municipal wastewater (black and gray) by UASB process. The purpose of this study is to explore the pollution load of these wastewaters and their treatment potential use in upflow anaerobic sludge blanket process. The general characterization of wastewater, treatment in UASB reactor with operational parameters and reactor performance in terms of COD removal and biogas production are thoroughly discussed in the paper. The concrete data illustrates the reactor configuration, thus giving maximum awareness about upflow anaerobic sludge blanket reactor for further research. The future aspects for research needs are also outlined.     

Evaluation of kinetic constants for anaerobic fixed film fixed bed reactors treating tannery wastewater

An approach has been made to evaluate the kinetic constants for a two stage anaerobic fixed film fixed bed reactor system treating tannery wastewater. The research reported herein is concerned with the bench scale performance evaluation of the reactor system treating the wastewater and application of the data to various models to evaluate the kinetic constants for substrate bio‐oxidation, biomass growth and biogas yield.     

Removal of residual dissolved methane gas in an upflow anaerobic sludge blanket reactor treating low-strength wastewater at low temperature with degassing membrane

In this study, we investigated the efficiency of dissolved methane (D-CH₄) collection by degasification from the effluent of a bench-scale upflow anaerobic sludge blanket (UASB) reactor treating synthetic wastewater. A hollow-fiber degassing membrane module was used for degasification. This module was connected to the liquid outlet of the UASB reactor. After chemical oxygen demand (COD) removal efficiency of the UASB reactor became stable, D-CH₄ discharged from the UASB reactor was collected. Under 35 °C and a hydraulic retention time (HRT) of 10 h, average D-CH₄ concentration could be reduced from 63 mg COD L⁻¹ to 15 mg COD L⁻¹; this, in turn, resulted in an increase in total methane (CH₄) recovery efficiency from 89% to 97%. Furthermore, we investigated the effects of temperature and HRT of the UASB reactor on degasification efficiency. Average D-CH₄ concentration was as high as 104 mg COD L⁻¹ at 15 °C because of the higher solubility of CH₄ gas in liquid; the average D-CH₄ concentration was reduced to 14 mg COD L⁻¹ by degasification. Accordingly, total CH₄ recovery efficiency increased from 71% to 97% at 15 °C as a result of degasification. Moreover, degasification tended to cause an increase in particulate COD removal efficiency. The UASB reactor was operated at the same COD loading rate, but different wastewater feed rates and HRTs. Although average D-CH₄ concentration in the UASB reactor was almost unchanged (ca. 70 mg COD L⁻¹) regardless of the HRT value, the CH₄ discharge rate from the UASB reactor increased because of an increase in the wastewater feed rate. Because the D-CH₄ concentration could be reduced down to 12 ± 1 mg COD L⁻¹ by degasification at an HRT of 6.7 h, the CH₄ recovery rate was 1.5 times higher under degasification than under normal operation.     

Optimum cycle time for intermittent UASB reactors treating dairy wastewater

This work accesses the influence of cycle duration on the intermittent operation of mesophilic UASB reactors inoculated with flocculent sludge and used in dairy wastewater (DWW) treatment. Five cycle lengths ranging from 24 to 144 h were compared for loads between 2.5 and 29.0 gCOD/l/d. COD balances are presented which demonstrate the importance of a feedless period in the conversion to methane of the substrates removed during the feed period. The maximum applicable loads determined for the system were higher for the longer cycle times. The higher conversion to methane of the removed COD was obtained for the 96 h cycle (48 h feed + 48 h feedless) resulting in a more stable operation. The 96 h cycle (48 h feed + 48 h feedless) was considered as the optimum for the treatment of dairy effluents in intermittent UASB reactors. Compared to the maximum applicable loads reported in the literature for continuous systems (3-6 gCOD/l/d) treating dairy effluents the stable operation loads attained with intermittent operation were considerably higher (22 gCOD/l/d).     

Enhanced granulation by natural ionic polymer additives in UASB reactor treating low-strength wastewater

Effect of natural ionic polymer additives on granulation in lab-scale UASB reactors treating low-strength synthetic wastewater (COD 750-850 mg/L) was examined. The organic loading rate was 1.477+/-0.118 kgCOD/m3/day. Under identical conditions four similar reactors were operated in parallel with the following additives: control with no additive, anionic part of Reetha (Sapindus trifoliata) extract, cationic part of Reetha extract, and Chitosan. By the end of the study period, Chitosan as an additive produced largest granules with mean size of 0.15 mm closely followed by the cationic fraction of the Reetha extract with mean size of 0.144 mm, and anionic fractions of the Reetha extract with 0.139 mm. Control reactor with no additives had the smallest size granules with mean size of 0.128 mm. The fraction of granules in the sludge bed of size >0.1 mm showed similar trend. The largest granule size observed in the reactors with additives was 4-5mm as compared to 2 mm in the control reactor. Cationic polymers were more effective additives for enhancing sludge granulation. Exo-cellular protein, lipid, sugar and total polymer increased with granulation in the reactors. A COD removal efficiency of 95-98% was achieved in all the reactors.     

Comparison of two different anaerobic feeding strategies to establish a stable aerobic granulated sludge bed

Two different anaerobic feeding strategies were compared to optimize the development and performance of aerobic granules. A stable aerobic granulation of activated sludge was achieved with an anaerobic plug flow operation (PI) and a fast influent step followed by an anaerobic mixing phase (PII). Two lab scale sequencing batch reactors (SBRs) were operated to test the different operation modes. PI with plug flow and a reactor H/D (height/diameter) ratio of 9 achieved a biomass concentration of 20 g_TSS/L and an effluent TSS concentration of 0.10 g_TSS/L. PII with the mixed anaerobic phase directly after feeding and a reactor H/D ratio of 2 achieved a biomass concentration of 9 g_TSS/L and an effluent quality of 0.05 g_TSS/L. Furthermore, it is shown that the plug flow regime during anaerobic feeding together with the lower H/D ratio of 2 led to channeling effects, which resulted in lower storage of organic carbon and a general destabilization of the granulation process. Compared to the plug flow regime (PI), the anaerobic mixing (PII) provided lower substrate gradients within the biofilm. However, these disadvantages could be compensated by higher mass transfer coefficients in PII (k_L = 0.3 m/d for PI; k_L = 86 m/d for PII) during the anaerobic phase.     

Anaerobic biodegradability and treatment of grey water in upflow anaerobic sludge blanket (UASB) reactor

Feasibility of grey water treatment in an upflow anaerobic sludge blanket (UASB) reactor operated at different hydraulic retention time (HRT) of 16, 10 and 6h and controlled temperature of 30 degrees C was investigated. Moreover, the maximum anaerobic biodegradability without inoculum addition and maximum removal of chemical oxygen demand (COD) fractions in grey water were determined in batch experiments. High values of maximum anaerobic biodegradability (76%) and maximum COD removal in the UASB reactor (84%) were achieved. The results showed that the colloidal COD had the highest maximum anaerobic biodegradability (86%) and the suspended and dissolved COD had similar maximum anaerobic biodegradability of 70%. Furthermore, the results of the UASB reactor demonstrated that a total COD removal of 52-64% was obtained at HRT between 6 and 16 h. The UASB reactor removed 22-30% and 15-21% of total nitrogen and total phosphorous in the grey water, respectively, mainly due to the removal of particulate nutrients. The characteristics of the sludge in the UASB reactor confirmed that the reactor had a stable performance. The minimum sludge residence time and the maximum specific methanogenic activity of the sludge ranged between 27 and 93 days and 0.18 and 0.28 kg COD/(kg VS d).     

Heterotroph anoxic yield in anoxic aerobic activated sludge systems treating municipal wastewater

As input to the steady state design and kinetic simulation models for the activated sludge system, the correct value for the heterotroph anoxic yield is essential to provide reliable estimates for the system denitrification potential. This paper examines activated sludge anoxic yield values in the literature, and presents experimental data quantifying the value. In the literature, in terms of the structure of ASM1 and similar models, theoretically it has been shown that the anoxic yield should be reduced to approximately 0.79 the value of the aerobic yield. This theoretical value is validated with data from corresponding aerobic OUR and anoxic nitrate time profiles in a batch fed laboratory scale long sludge age activated sludge system treating municipal wastewater. The value also is in close agreement with values in the literature measured with both artificial substrates and municipal wastewater. Thus, it is concluded that, in ASM1 and similar models, for an aerobic yield of 0.67mg COD/mg COD, the anoxic yield should be about 0.53 mg COD/mg COD. Including such a lower anoxic yield in ASM1 and similar models will result in a significant increase in denitrification potential, due to increased denitrification with wastewater RBCOD as substrate. In terms of the structure of ASM3, for the proposed substrate storage yields and the aerobic yield of 0.63 mg COD/mg COD, experimental data indicate that the corresponding anoxic yield should be about 0.42 mg COD/mg COD. This is significantly lower than the proposed value of 0.54 mg COD/mg COD, and requires further investigation.     

Accelerated start-up and enhanced granulation in upflow anaerobic sludge blanket reactors

In the present study, the effects of a cationic polymer on reactor start-up and granule development were evaluated. A control reactor R1 was operated without adding polymer, while the other five reactors designated R2, R3, R4, R5 and R6 were operated with different polymer concentrations of 20, 40, 80, 160 and 320 mg/L, respectively. Experimental results demonstrated that adding the polymer at a concentration of 80 mg/L markedly accelerated the start-up time. The time required to reach stable treatment at an organic loading rate (OLR) of 4 g COD/L.d was reduced by approximately 50% in R4 as compared with the control reactor. The same reactor with 80 mg/L polymer was able to achieve an OLR of 12 g COD/L.d after 59 days of operation, while R1, R2, R3, R5 and R6 achieved the same loading rate at much longer period of 104, 80, 69, 63 and 69 days, respectively. Comparing with the control reactor, the start-up time of R4 was shortened markedly by about 43% at this OLR, while other reactors also recorded varying degree of shortening. Monitoring on granule development showed that the granule formation was accelerated by 30% from the use of the appropriate dosage of polymer. Subsequent granules characterization indicated that the granules developed in R4 with 80 mg/L polymer exhibited the best settleability, strength and methanogenic activity at all OLRs. The organic loading capacities of reactors were also increased by the polymer addition. The maximum organic loading of the control reactor was 24 g COD/L.d, while the polymer-assisted reactor added with 80 mg/L polymer attained a markedly increased organic loading of 40 g COD/L.d. The laboratory results obtained demonstrated that adding the cationic polymer could result in shortening of start-up time and enhancement of granulation, which in turn lead to improvement in organics removal efficiency and loading capacity of the UASB system.     

Treatment of phenol and cresols in upflow anaerobic sludge blanket (UASB) process: a review

Upflow anaerobic sludge blanket (UASB) process has been successfully applied in the treatment of municipal and industrial wastewaters. Several researchers have investigated the suitability of the process for the treatment of phenols and phenolic wastewaters. The anaerobic treatment of phenols is still at an investigative stage. With increasing recognition of the UASB process, feasibility studies on the treatment of wastewater containing phenol and cresols (o-, m- and p- isomers) in UASB have been reviewed. It is reported that phenol concentration up to a range of 500-750 mg/L is generally not inhibitory to the UASB process. Phenol concentrations greater than 500 mg/L can be effectively treated with acclimatization of inocula, recirculation of the treated effluent and/or supplementing with co-substrates such as glucose, VFA and dilute molasses. The degradability of phenol is more than p-cresol, which in turn is more than m- and o-cresol.     

The effect of hydraulic retention time on granular sludge biomass in treating textile wastewater

The physical characteristics, microbial activities and kinetic properties of the granular sludge biomass were investigated under the influence of different hydraulic retention times (HRT) along with the performance of the system in removal of color and COD of synthetic textile wastewater. The study was conducted in a column reactor operated according to a sequential batch reactor with a sequence of anaerobic and aerobic reaction phases. Six stages of different HRTs and different anaerobic and aerobic reaction time were evaluated. It was observed that the increase in HRT resulted in the reduction of organic loading rate (OLR). This has caused a decrease in biomass concentration (MLSS), reduction in mean size of the granules, lowered the settling ability of the granules and reduction of oxygen uptake rate (OUR), overall specific biomass growth rate (ì_overall), endogeneous decay rate (k_d) and biomass yield (Y_obs, Y). When the OLR was increased by adding carbon sources (glucose, sodium acetate and ethanol), there was a slight increase in the MLSS, the granules mean size, ì_overall, and biomass yield. Under high HRT, increasing the anaerobic to aerobic reaction time ratio caused an increase in the concentration of MLSS, mean size of granules and lowered the SVI value and biomass yield. The ì_overall and biomass yield increased with the reduction in anaerobic/aerobic time ratio. The HRT of 24 h with anaerobic and aerobic reaction time of 17.8 and 5.8 h respectively appear to be the best cycle operation of SBR. Under these conditions, not only the physical properties of the biogranules have improved, the highest removal of color (i.e. 94.1 ± 0.6%) and organics (i.e. 86.5 ± 0.5%) of the synthetic textile dyeing wastewater have been achieved.     

改良UASB反应器处理海藻酸钠废水的试验研究

本试验采用改良UASB反应器在常温条件下现场处理海藻酸钠废水,试验历时94 d,在絮状污泥为主条件下,容积负荷6.0 kgCOD/(m3.d)时,COD去除率达到85%,出水pH 6.8左右,VFA稳定在400 mg/L左右,设备运行稳定.试验结果表明,常温下利用改良UASB处理海带渣废水是可行的.     

Methanogenic community shift in anaerobic batch digesters treating swine wastewater

Qualitative and quantitative molecular analysis techniques were used to determine associations between differences in methanogenic microbial communities and the efficiency of batch anaerobic digesters. Two bioreactors were initially seeded with anaerobic sludge originating from a local municipal wastewater treatment plant and then supplemented with swine wastewater. Differences were observed in the total amount of methane produced in the two bioreactors (7.9 L/L, and 4.5 L/L, respectively). To explain these differences, efforts were taken to characterize the microbial populations present using a PCR-based DGGE analysis with methanogenic primer and probe sets. The groups Methanomicrobiales (MMB), Methanobacteriales (MBT), and Methanosarcinales (MSL) were detected, but Methanococcales (MCC) was not detected. Following this qualitative assay, real-time PCR was used to investigate quantitative differences in the populations of these methanogenic orders. MMB was found to be the dominant order present and its abundance patterns were different in the two digesters. The population profiles of the other methanogenic groups also differed. Through redundancy analysis, correlations between the concentrations of the different microbes and chemical properties such as volatile fatty acids were calculated. Correlations between MBT and MSL populations and chemical properties were found to be consistent in both digesters, however, differences were observed in the correlations between MMB and propionate. These results suggest that interactions between populations of MMB and other methanogens affected the final methane yield, despite MMB remaining the dominant group overall. The exact details of why changes in the MMB community caused different profiles of methane production could not be ascertained. However, this research provides evidence that microbial behavior is important for regulating the performance of anaerobic processes.     

The characteristics of granules from upflow anaerobic sludge blanket reactors

Granules from an industrial UASB reactor were maintained in bench scale (201.) UASB reactors and fed with a synthetic medium based on volatile fatty acids.

After 60 days of reactor operation, three distinct granule types were found to have evolved within the reactors. These types were defined by their colour: black, grey and white. These granules also differed in structure (texture) and elemental composition. The proportion of black, grey and white granules in the bed changed when the organic loading rate was changed. At the low loading rate, a large number of “hollow” granules appeared which were less dense than the liquid and were washed out at the top of the reactor.     

Operating aerobic wastewater treatment at very short sludge ages enables treatment and energy recovery through anaerobic sludge digestion

Conventional abattoir wastewater treatment processes for carbon and nutrient removal are typically designed and operated with a long sludge retention time (SRT) of 10–20 days, with a relatively high energy demand and physical footprint. The process also generates a considerable amount of waste activated sludge that is not easily degradable due to the long SRT. In this study, an innovative high-rate sequencing batch reactor (SBR) based wastewater treatment process with short SRT and hydraulic retention time (HRT) is developed and characterised. The high-rate SBR process was shown to be most effective with SRT of 2–3 days and HRT of 0.5–1 day, achieving >80% reduction in chemical oxygen demand (COD) and phosphorus and approximately 55% nitrogen removal. A majority of carbon removal (70–80%) was achieved by biomass assimilation and/or accumulation, rather than oxidation. Anaerobic degradability of the sludge generated in the high-rate SBR process was strongly linked to SRT, with measured degradability extent being 85% (2 days SRT), 73% (3 days), and 63% (4 days), but it was not influenced by digestion temperature. However, the rate of degradation for 3 and 4 days SRT sludge was increased by 45% at thermophilic conditions compared to mesophilic conditions. Overall, the treatment process provides a very compact and energy efficient treatment option for highly degradable wastewaters such as meat and food processing, with a substantial space reduction by using smaller reactors and a considerable net energy output through the reduced aerobic oxidation and concurrent increased methane production potential through the efficient sludge digestion.     

Characterization of microbial trophic structures of two anaerobic bioreactors processing sulfate-rich waste streams

A multi-compartment anaerobic bioreactor, designated the anaerobic migrating blanket reactor (AMBR), did not perform well in terms of chemical oxygen demand (COD) removal after an increase in sulfate load, compared to a conventional upflow anaerobic sludge blanket (UASB) reactor. The trophic structures of the bioreactors were characterized by analyzing the electron flows, formation and consumption of fermentation intermediates and terminal product (methane and hydrogen sulfide) formation. Critical performance parameters were linked to operational perturbations such as increase in sulfate load and changes in flow reversal schemes in the AMBR. Both of these manipulations affected the microbial communities, which were monitored by terminal restriction fragment length polymorphism (T-RFLP) analysis targeting the bacterial and archaeal domains. The less stable AMBR did not produce granular biomass, and in response to increased sulfate concentrations, experienced a reversal in the distribution of hydrogenotrophic methanogens that correlated with a shift in electron flow from butyrate to propionate. As this shift occurred, bacterial populations such as butyrate-producing clostridia, became predominant, thus leading to reactor imbalance. The stable UASB reactor developed and retained granules and maintained a relatively stable archaeal community. Sulfate perturbation led to the selection of a novel bacterial group (Thermotogaceae), which was most likely well adapted to the increasingly sulfidogenic conditions in the bioreactor.