Combined Upflow Anaerobic Sludge Blanket Research Articles

Study on the Treatment of Refined Sugar Wastewater by Electrodialysis Coupled with Upflow Anaerobic Sludge Blanket and Membrane Bioreactor.

In this paper, refined sugar wastewater (RSW) is treated by electrodialysis (ED) coupled with an upflow anaerobic sludge blanket (UASB) and membrane bioreactor (MBR). The salt in RSW was first removed by ED, and then the remaining organic components in RSW were degraded by a combined UASB and MBR system. In the batch operation of ED, the RSW was desalinated to a certain level (conductivity < 6 mS·cm-1) at different dilute to concentrated stream volume ratios (VD/VC). At the volume ratio of 5:1, the salt migration rate JR and COD migration rate JCOD were 283.9 g·h-1·m-2 and 13.84 g·h-1·m-2, respectively, and the separation factor α (defined as JCOD/JR) reached a minimum value of 0.0487. The ion exchange capacity (IEC) of ion exchange membranes (IEMs) after 5 months of usage showed a slight change from 2.3 mmol·g-1 to 1.8 mmol·g-1. After the ED treatment, the effluent from the tank of the dilute stream was introduced into the combined UASB-MBR system. In the stabilization stage, the average COD of UASB effluent was 2048 mg·L-1, and the effluent COD of MBR was maintained below 44-69 mg·L-1, which met the discharge standard of water contaminants for the sugar industry. The coupled method reported here provides a viable idea and an effective reference for treating RSW and other similar industrial wastewaters with high salinity and organic contents.

Swine wastewater treatment using combined up-flow anaerobic sludge blanket and anaerobic membrane bioreactor: Performance and microbial community diversity

To address the existing economic and environmental issues associated with swine wastewater (SW) treatment, a process combining up-flow anaerobic sludge blanket (UASB) and anaerobic membrane bioreactor (AnMBR) was developed and continuously operated for 137 d. Bioreactor conversion and microbial community dynamics in reactors were analyzed. The UASB–AnMBR process yielded excellent pollutants removal efficiencies of 96% and 63% for chemical oxygen demand (COD) and total phosphorous (TP), respectively. More than 60% of Firmicutes (Terrisporobacter, Turicibacter, and Clostridium sensu stricto 1), which were dominated by Methanosaeta and Methanobacterium with relative abundances of 58.6% and 36.8% in the UASB and 22.5% and 40.3% in the AnMBR, respectively, converted complex compounds into organic acids for methanogenesis. This research presented an analysis of pollutants removal and microbial dynamics of UASB–AnMBR, which significantly affected the large-scale application of UASB–AnMBR process.

Artificial neural network based models for predicting the effluent quality of a combined upflow anaerobic sludge blanket and facultative pond: Performance evaluation and comparison of different algorithms

The main objective of this work was to test different artificial neural network (ANN) based models, i.e. the ANN feed forward back propagation (ANN-FFBP), deep feed forward backpropagation (DFFBP), and deep cascade forward back propagation (DCFBP) models, for predicting the effluent quality of an upflow anaerobic sludge blanket-facultative pond (UASB-FP) system. The overall removal efficiency in the UASB-FP was >84% at organic loading rates of ∼26 kg d−1. The chemical oxygen demand (COD), ammonical nitrogen (AN), total suspended solids (TSS), biochemical oxygen demand (BOD), total Kjeldahl nitrogen (TKN), and total phosphorus (TP) were inputs to each model, while the water quality characteristics of the UASB-FP effluent was used as the output. The dataset of 180 samples, collected over a one-year period, was utilized to train, test, and validate the developed models. Compared to ANN-FFBP and DFFBP, the DCFBP network demonstrated the strongest capacity for prediction. The correlation coefficient RTrain and the root-mean-squared error (RMSE) for the selected DCFBP model (3 hidden layers and 11 neurons/layer) in the training data set were 0.997 and 6.018, respectively. The sensitivity analysis of the DCFBP model shows that the model's performance is very sensitive to BOD followed by AN, COD, TP, TSS and TKN, respectively. The results of this study will be helpful to wastewater treatment (WWTP) plant managers in their pursuit of data-driven UASB-FP based WWTP management.

Development of UASB–DHS System for Anaerobically-Treated Tofu Processing Wastewater Treatment under Ambient Temperature

Tofu is widely processed in East and Southeast Asian countries. During the production, highly polluted wastewater is discharged. This wastewater is commonly treated using a high-rate anaerobic wastewater treatment process; however, several organic compounds and nitrogen remain in the anaerobic effluent. The aim of this study was to develop a combined upflow anaerobic sludge blanket (UASB) and downflow hanging sponge (DHS) biosystem that that serves as a post-treatment for an expanded granular sludge blanket reactor used for treating tofu-processing wastewater in Japan for 699 days. The UASB reactor played a role in treating of COD, with 58 ± 16% and 74 ± 20% of total COD and soluble COD removed anaerobically. Besides, methane was recovered from removed soluble COD were 63 ± 28% and 87 ± 64% at winter and summer. Meanwhile, the DHS reactor showed its potential in treatment of BOD and TSS. The final effluents were recorded as 67 ± 38 mg·L-1, 50 ± 26 mg·L-1, and 22 ± 16 mg·L-1 of total COD, BOD and total suspended solids, respectively. This indicates that the proposed UASB-DHS system has proven its suitability as post-treatment system for anaerobically treated tofu-processing wastewater

Anaerobic biological treatment of EG/PG water-soluble copolymer coupled with down-flow hanging sponge reactor

Water-soluble copolymers such as polyvinylpyrrolidone and polyvinyl alcohol have been widely used as detergents, paints, and chemical intermediates in many industrial processes, leading to environmental concerns associated with high-volume organic compound wastewater. Therefore, in this study, a combined upflow anaerobic sludge blanket (UASB) reactor and downflow hanging sponge (DHS) biosystem has been applied for the treatment of synthetic water-soluble copolymer wastewater. Copolymer consisted of ethylene glycol and propylene glycol with a total molecular weight of 8,500, commonly preferred in the automobile parts processing factory, were included in influent. Overall, the whole UASB–DHS system achieved a favorable chemical oxygen demand (COD) removal efficiency of 86% ± 7%. In more detail, with an organic loading rate of 2.12 kg-COD ⋅ m −3 ⋅ day −1 , the UASB reactor enhanced the biodegradability of wastewater, and reached COD removal efficiency of 61% ± 16%. Meanwhile, gel permeation chromatography analysis indicated that the molecular weight of the wastewater was primarily reduced in the DHS reactor. In addition, massive 16S rRNA gene sequencing showed that polyethylene-glycol-degrading bacteria Pelobacter sp. was predominant in the UASB granular sludge. • First report on integrated biological treatment of water-soluble copolymers. • UASB reactor after adaptation can recover energy in the form of methane. • Total system achieved chemical oxygen demand removal efficiency of 86% ±7%. • Molecular weight reduction in the process was mainly occurred in the DHS. • UASB-DHS system was applicable to this wastewater.

Estimation of effluent parameters of slaughterhouse wastewater treatment with artificial neural network and B-spline quasi interpolation

Effluent of slaughterhouse wastewater treatment by combined up-flow anaerobic sludge blanket (UASB) reactor and extended aeration reactor was estimated through artificial neural networks (ANN), ANN-genetic algorithm (GA) and B-spline quasi interpolation. The overall system operated at two runs with average total chemical oxygen demand (TCOD) of 1514.65 and 3160.2 mg/L for the first and second run, respectively; with two overall hydraulic retention times of 73 and 104 h for each run. The overall system could remove TCOD, ammonia, phosphate and turbidity to a high extent. The multilayer perceptron artificial neural network (MLPANN) trained by Levenberge–Marquardt algorithm was employed to predict the TCOD, ammonia, phosphate and turbidity of the effluent which resulted in R of 0.8257, 0.6274, 0.7961 and 0.6884, respectively. The optimization of MLPANN by GA performed better than MLPANN with R of 0.8390, 0.7650, 0.8107 and 0.7365 for TCOD, ammonia, phosphate and turbidity, respectively. The B-spline quasi interpolation indicates a more accurate prediction due to its R of 0.9619, 0.8806, 0.8307 and 0.7856 for TCOD, ammonia, phosphate and turbidity, respectively. The B-spline quasi interpolation operation time is notably lower than ANN and ANN-GA. In addition, it has a simple algorithm and is implemented easier than the artificial neural network model.

Feasibility of combined upflow anaerobic sludge blanket-aerobic membrane bioreactor system in treating purified terephthalic acid wastewater and polyimide membrane for biogas purification

Anaerobic processes have become actively practiced for waste and wastewater treatment during the recent years because it can apply for high organic loading whereas the producing biogas can be recovered as a new energy source. This study prompted to look on the feasibility of a combined upflow anaerobic sludge blanket (UASB) and aerated membrane bioreactor (MBR) system for the treatment of purified terephthalic acid (PTA) wastewater and the usage of polyimide membranes for biogas separation. The results revealed that the combined system is robust and flexible in relation to the change in hydraulic retention times (HRTs) and organic loading rates. The overall chemical oxygen demand (COD) removal of 97% with the maximum loading rate of 20gL−1 per day was achieved at 12h HRT. The biogas from the UASB reactor was mainly methane (>62%). The separation between CO2 and CH4 was explored using different concentrations of dense polyimide (PIs) membranes and feed pressure. The results revealed that PIs based membranes possess high potential for CH4 purification with high selectivity and permeability towards CO2 than CH4. The expediency of the proposed treatment system and gas-separating module was seen and thus purified biomethane could be mustered continuously.

A combined upflow anaerobic sludge bed and trickling biofilter process for the treatment of swine wastewater

ABSTRACTA combined upflow anaerobic sludge blanket (UASB)-trickling biofilter (TBF) process was constructed to treat swine wastewater, a typical high-strength organic wastewater with low carbon/nitrogen ratio and ammonia toxicity. The results showed that the UASB-TBF system can remarkably enhance the removal of pollutants in the swine wastewater. At an organic loading rate of 2.29 kg/m3 d and hydraulic retention time of 48 h in the UASB, the chemical oxygen demand (COD), Suspended Solids and Total Kjeldahl Nitrogen removals of the combined process reached 83.6%, 84.1% and 41.2%, respectively. In the combined system the UASB served as a pretreatment process for COD removal while nitrification and denitrification occurred only in the TBF process. The TBF performed reasonably well at a surface hydraulic load as high as 0.12 m3/m2 d. Since the ratio of influent COD to total mineral nitrogen was less than 3.23, it is reasonable to suggest that the wood chips in TBF can serve as a new carbon source for denitrification.

Evaluation of performance in a combined UASB and aerobic contact oxidation process treating acrylic wastewater

The lab-scale and full-scale performance of a combined mesophilic up-flow anaerobic sludge blanket (UASB) and aerobic contact oxidation (ACO) process for treating acrylic wastewater was studied. During lab-scale experiment, the overwhelmed volumetric load for UASB was above 6 kg chemical oxygen demand (COD) ·(m−3·d−1) since COD removal efficiency dropped dramatically from 73% at 6 kg COD·(m−3·d−1) to 61% at 7 kg COD·(m−3·d−1) and 53% at 8 kg COD·(m−3·d−1). Further results showed that an up-flow fluid velocity of 0.5 m h−1 for UASB obtained a highest COD removal efficiency of 75%, and the optimum COD volumetric load for the corresponding ACO was 1.00 kg COD·(m−3·d−1). Based on the configuration of the lab-scale experiment, a full-scale application with an acrylic wastewater treatment capacity of 8 m3 h−1 was constructed and operated at a volumetric load of 5.5 kg COD·(m−3·d−1), an up-flow fluid velocity of 0.5 m h−1 for UASB and a volumetric load of 0.9 kg COD·(m−3·d−1) for ACO; and the final effluent COD was around 740 mg L−1. The results suggest that a combined UASB–ACO process is promising for treating acrylic wastewater.

The combined UASB and MBR system to COD and TSS removal and excess sludge reduction for the treatment of high strength wastewater in various operational temperatures

There are many activated sludge plants (ASP) in Iran. Most of them are overloaded and as a result their efficiency is very low. A combined laboratory-scale system (5 L reactors) consisting of an up-flow anaerobic sludge blanket (UASB) and aerobic membrane bioreactor (MBR) was operated at 20 and 30°C with pH between 7.6 and 8.4. The experiment was run to optimize treatment of high-strength enriched municipal wastewater of the Ekbatan treatment plant located in west Tehran. The chemical oxygen demand (COD) of the wastewater was enriched due to the addition of molasses and milk powder. To prevent pH fluctuation of the influent, NaHCO3 and K2HPO4 were added to the wastewater. The excess sludge from the MBR was recirculated into the UASB. The system treated fortified municipal wastewater with a volumetric COD loading rate of 600, 1,200, 1,800, and 2,400 mg/L, and temperatures at 20 and 30°C. The results of the present work indicate an optimum organic loading (7.2–10.8 kg m−3 d−1) with COD removal efficiency (RE) between 74 and 85% in both examined temperatures in UASBR. The total combined system efficiency was, approximately, 98% in COD removal and 100% in total suspended solids removal. Furthermore, the nitrate RE was about 80%. Also, excess sludge reduction was over 90%, and the optimum hydraulic retention time for influent COD concentration of 1,200 mg l−1 is shown to be 4 h. This upgraded system increases the treatment capacity by factor of 5.

Biotreatment of heavy oil wastewater by combined upflow anaerobic sludge blanket and immobilized biological aerated filter in a pilot-scale test

A field pilot study has been constructed in the Liaohe oilfield, China to treat heavy oil wastewater with large amounts of dissolved recalcitrant organic compounds and low nutrient of nitrogen and phosphorus by an upflow anaerobic sludge blanket (UASB) coupled with immobilized biological aerated filters (I-BAFs). By operating the system for 252 days (including the start-up of 128 days), the chemical oxygen demand (COD), ammonia nitrogen (NH3-N) and suspended solid (SS) in the wastewater were removed by 74%, 94% and 98%, respectively. GC–MS analysis indicated that most of alkanes were degraded by the UASB process, while the I-BAF played important roles both in degrading organic compounds and in removing the NH3-N and SS. The bacterial community structural analysis based on the PCR-DGGE technology reveals that the predominant bacteria in the UASB reactor belong to the Bacillales and Rhodobacterales, and that in the I-BAF was identified as uncultured soil bacterium. Our results suggest that the combined biotreatment system has immense potential in large-scale treatment of heavy oil wastewater.

Treatability of landfill leachate by combined upflow anaerobic sludge blanket reactor and aerated lagoon

Continuous upflow anaerobic sludge blanket reactor performs more favorably at the higher organic loading rate than other anaerobic treatment. The treatment of municipal landfill leachate of Shiraz’s city investigated using continuous flow anaerobic reactor and subsequently aerated lagoon. Landfill leachate has chemical oxygen demand of 45,000–90,000 mg/L and ammonia nitrogen at 1,000–2,500 and heavy metals that can impact biological treatments. Capacity of anaerobic and aerobic reactors is 10 and 20 L that operated at detention time of 2 and 4 days, respectively. Organic loading rate of upflow anaerobic sludge blanket is between 0.5–20 g chemical oxygen demand/L/day. Chemical oxygen demand removal efficiencies are between 57–87, 35–70 and 66–94% in the anaerobic, aerobic and whole system, respectively. As the entry, leachate organic loading rate increased from 1 to 20 g/L/day, the chemical oxygen demand removal efficiency reached a maximum of 71% and 84% in the anaerobic reactor and whole system, respectively, at high organic loading rate. Ammonium removal efficiency was about 54% after the aerobic stage.

Evaluation of UASB/CO2 stripping system for simultaneous removal of organics and calcium in linerboard wastewater

A combined upflow anaerobic sludge blanket (UASB) and CO2-stripping system was evaluated for its capacity to simultaneously remove organic compounds and calcium from linerboard mill wastewater. A continuous-flow UASB has significant potential to remove organic compounds, and its removal efficiency is closely related to volumetric organic loading. After the UASB process, a gradual decrease of pH was observed and CO2-stripping indicated the formation of acid/methane and carbonate. The high concentration of carbonate that was generated from the elevated pH of the CO2 stripper easily reacted with calcium in the wastewater to form a solid-phase calcium carbonate. The significant amount of methane that was produced during the UASB process implies that methane-producing bacteria dominate the microbial composition of the reactor. In the CO2 stripper system, calcium removal and alkalinity consumption rose simultaneously with increasing solution pHs. This result suggests that the combined activity of the UASB reactor and the CO2 stripper system is a powerful tool for removing organic compounds and calcium from linerboard wastewater. Such a system would allow water from the linerboard production process to be reused and be discharged with fewer toxic compounds. © 2010 American Institute of Chemical Engineers Environ Prog, 2011

Simultaneous Bioenergy (CH4) Production and Nitrogen Removal in a Combined Upflow Anaerobic Sludge Blanket and Aerobic Membrane Bioreactor

In this study, the effect of the aeration rate on simultaneous methanogenesis and denitrification was investigated in a combined system consisting of an oxygen-limited upflow anaerobic sludge blanket (UASB) and aerobic membrane bioreactor (MBR). Different oxygen concentrations in the UASB were achieved by recycling the mixed liquor of the aerobic MBR into the bottom of the UASB. The dissolved oxygen (DO) of the aerobic MBR mixed liquor was determined by the aeration rate in the aerobic MBR. Quantitative analysis of biogas production and composition and total organic carbon (TOC) and total nitrogen (TN) removal performances at different aeration rates in the aerobic MBR were carried out. Results showed that TOC and TN removal performances were improved in the combined system compared to a strictly anaerobic UASB. TOC removal efficiency up to 98% after membrane filtration was achieved. TN removal efficiency was related to the aeration rate in the aerobic MBR, which was limited by the nitrification efficiency at a low aeration rate and improved at aeration rates above 2.5 L/min. Biogas production and composition were also investigated. Results showed that a low DO concentration and degradation of NO x - -N through the denitrification process did not affect the methane production. A slight increase in methane production because of the improvement in the TOC removal rate and decrease of CO 2 at a low aeration rate was observed. However, methane production and the ratio decreased at a high aeration rate as a result of more nitrogen and CO 2 being produced via the processes of denitrification and oxidation, respectively. In this study, above 50% methane in the biogas and 80% TN and 98% TOC removal efficiencies at the aeration rates between 2.5 and 5.0 L/min in the aerobic MBR could be successfully achieved. On the basis of these results, it was suggested that simultaneous methanogenesis and denitrification could be employed as a bioenergy production technology using a combined UASB and aerobic MBR.

The integration of methanogenesis with shortcut nitrification and denitrification in a combined UASB with MBR

A combined system consisting of an up-flow anaerobic sludge blanket (UASB) and an aerobic membrane bioreactor (MBR) was operated at 28–30 °C and pH 7.8–8.1 for the treatment of low-strength synthetic wastewater enriched with organic carbon and NH 4Cl. The MBR slurry was recirculated into the UASB with a ratio of 50–800%. It was found that nitrite was able to accumulate steadily during the nitrification step in the MBR at a low TOC / NH 4 + –N ratio. The mixed liquid containing NO X - –N in the MBR was recirculated to the UASB, and denitrification rather than methanogenesis became the preferred pathway. Whereas, the less carbon requirement for denitrification via nitrite rather than nitrate allowed methanogenesis to proceed simultaneously in the same reactor. The combination of membrane filtration and partial nitrification in the MBR with simultaneous denitrification and methanogenesis in the UASB could stably reach 98% TOC removal and 48.1–82.8% TN removal with recirculation ratio increasing from 50% to 800%.

Sewage treatment in a combined up-flow anaerobic sludge blanket (UASB)–down-flow hanging sponge (DHS) system

The performance of up-flow anaerobic sludge blanket (UASB) in combination with down-flow hanging sponge (DHS) system for sewage treatment at an average wastewater temperature of 15 °C has been investigated for 6 months. The results showed that a combined system operated at a total HRT of 10.7 h and total SRT of 88 days represents a cost effective sewage treatment process. The average COD total and BOD 5 total concentrations measured in the final effluent of the total system (UASB + DHS) amounted to 43 and 3.0 mg/l, respectively, corresponding to the overall removal efficiency of 90% for COD total and 98% for BOD 5 total . The total process provided a final effluent containing a low concentration of 12 mg/l for TSS. Eighty-six percent of ammonia was eliminated at space loading rate of 1.6 kg COD/m 3 d and HRT of 2.7 h. The calculated nitrification rate of the DHS system according to the nitrate and nitrite production amounted to 0.18 kg/m 3 d. The removal of F. coliform in the UASB reactor only amounted to 0.86 log 10. On the other hand, the F. coliform concentration dropped substantially, i.e. by 2.6 log 10 in the DHS system resulting only 2.7 × 10 3/100 ml in the final effluent. The calculated average sludge production for UASB operated at an HRT of 8.0 h amounted to 30 g TSS/d, corresponding to sludge yield coefficient of 0.2 g TSS/g total COD removed, while it was indeed very low only 6.0 g TSS/d corresponding to sludge yield coefficient of 0.09 g TSS/g total COD removed, for DHS system. The DHS profile results revealed that in the first and second segment of DHS system, the COD total, BOD 5 total and TSS was eliminated, followed by the oxidation of ammonia in the next segments.

Combined UASB reactor and DAF/BF/anoxic/aerobic process for the removal of high-concentration organic matter and nutrients from slurry-type swine waste

This research aimed to effectively remove high-concentration organic matter and nutrients from slurry-type swine waste using a combined upflow anaerobic sludge blanket reactor with the dissolved air flotation/aerobic submerged biofilm/anoxic/aerobic process. The upflow anaerobic sludge blanket reactor was operated at an organics volumetric loading rate of 3.2-6.1 kg COD/m3/day, and the removal rates of COD were 53.9-65.5%. The removal rate of COD of the overall process was more than 99%. In the aerobic submerged biofilm, over 95% of ammonium nitrogen was removed at a volumetric loading rate of 0.08-0.16 kg NH4+-N/m3/day. The specific denitrification rate was 0.257 g NO3-N/g MLVSS/day and the removal rate of total nitrogen was 86.7%. Phosphorus was removed by flocculation in the dissolved air flotation process, and 0.16 g of PO4-P was removed by 1 g of ferric ion.

Evaluation and modelling of helminth eggs removal in baffled and unbaffled ponds treating anaerobic effluent

The paper evaluates and models helminth eggs removal in a combined UASB (Upflow Anaerobic Sludge Blanket) reactor-maturation pond system (one baffled and one unbaffled pond in parallel). The system is comprised of demonstration-scale units, treating actual domestic sewage from Itabira city, Brazil. The paper addresses the following points: (i) removal of helminth eggs from the wastewater in the system; (ii) comparison of the observed removal efficiency with the predictions using the Ayres et al. model; (iii) accumulation of helminth eggs in the sludge; (iv) viability of eggs in the sludge; (v) distribution of helminth species in the sludge. The removal efficiency of helminth eggs from the wastewater in both ponds was 100% for most of the time (0 counts in the final effluent). The predictions of helminth eggs removal according to the Ayres et al. model can be considered reasonable. After one year of operation, 88% of the eggs in the sludge remained viable. Helminth eggs counts in the sludge tended to decrease along the baffled pond length (from first to last compartment). The prevailing helminth species found in the sludge from both ponds was Ascaris lumbricoides.

Distribution and change of microbial activity in combined UASB and AFB reactors for wastewater treatment

A thermophilic upflow anaerobic sludge blanket (UASB) reactor was combined with a mesophilic aerobic fluidized bed (AFB) reactor for treatment of a medium strength wastewater with 2,700 mg COD l−1. The COD removal efficiency reached 75% with a removal rate of 0.2 g COD l−1 h−1 at an overall hydraulic retention time 14 hours. The distribution of microbial activity and its change with hydraulic retention time in the two reactors were investigated by measuring ATP concentration in the reactors and specific ATP content of the biomass. In the UASB reactor, the difference in specific ATP was significant between the sludge bed and blanket solution (0.02 mg ATP g VS−1 versus 0.85 mg ATP g VS−1) even though the ATP concentrations in these two zones were similar. A great pH gradient up to 4 was developed along the UASB reactor. Since a high ATP or biological activity in the blanket solution could only be maintained in a narrow pH range from 6.5 to 7.5, the sludge granules showed a high pH tolerance and buffering capacity up to pH 11. The suspended biomass in AFB reactor had a higher specific ATP than the biomass fixed in polyurethane carriers (1.6 mg ATP g VS−1 versus 1.1 mg ATP g VS−1), which implies a starvation status of the immobilized cells due to mass transfer limitation. The aerobes had to work under starvation conditions in this polishing reactor. The anaerobic biomass brought into AFB reactor contributed to an increase in suspended solids, but not the COD removal because of its fast deactivation under aerobic conditions. A second order kinetic model was proposed for ATP decline of the anaerobes. The results on distribution of microbial activity in the two reactors as well as its change with hydraulic retention time lead to further performance improvement of the combined anaerobic/aerobic reactor system.

Agro-Industry Wastewater Treatment

Treatment of agro-industry wastewater using the RBC system and the combined Upflow Anaerobic Sludge Blanket - Rotating Biological Contactor (UASB - RBC) system was investigated. The raw wastewater was highly contaminated with organic matter as indicated by COD (3500 – 4000 mgl−1), BOD5 (1620 – 1800 mgl−1), and TSS (375 – 402 mgl−1). RBC system led to an effluent that does not comply with the Egyptian Standards for discharging effluents to canals or drains. The combined system (UASB-RBC) achieved remarkable pollutants elimination. The treated effluent has BOD5 < 15 and COD < 40 mgO2 l−1. TSS, and oil and grease, are below the recommended limits for discharging industrial effluents into the surface water.