Biological treatment of a synthetic dairy wastewater in a sequencing batch biofilm reactor: Statistical modeling using optimization using response surface methodology

In this study, the interactive effects of initial chemical oxygen demand (CODin), biomass concentration and aeration time on the performance of a lab-scale sequencing batch biofilm reactor (SBBR) treating a synthetic dairy wastewater were investigated. The experiments were conducted based on a central composite design (CCD) and analyzed using response surface methodology (RSM). The region of exploration for treatment of the synthetic dairy wastewater was taken as the area enclosed by the influent comical oxygen demand (CODin (1000, 3000 and 5000 mg/l)), biomass concentration (3000, 5000 and 7000 mg VSS/l) and aeration time (2, 8 and 18 h) boundaries. Two dependent parameters were measured or calculated as response. These parameters were total COD removal efficiency and sludge volume index (SVI). The maximum COD removal efficiencies (99.5%) were obtained at CODin, biomass concentration and aeration time of 5000 mg COD/l, 7000 mg VSS/l and 18 h, respectively. The present study provides valuable information about interrelations of quality and process parameters at different values of the operating variables

Performance of an activated sludge followed by membrane process (AS-MP) treating simulated industrial wastewaters: effects of operating factors and feed characteristics

Abstract The main aim of the present study is to determine the optimum operating conditions for different feed compositions with less irreversible membrane fouling in an activated sludge followed by membrane process (AS-MP). In this regard, three different wastewaters with different BOD5/COD ratios (0.83 for soft drink, 0.63 for pineapple fruit juice and 0.36 for amoxicillin) as an index of biodegradability were selected. The AS-MP system was operated with biomass concentration of 7000–8000 mg/l and different hydraulic retention times (HRTs) in the range of 4–20 h. The optimal HRT was decreased as BOD5/COD ratio was increased. In order to investigate fouling behavior of membranes in the AS-MP, a commercial polyvinylidene fluoride (PVDF) microfiltration (MF) membrane and high-performance synthetic ZnFe2O4/SiO2 embedded polyether sulfone (PES) ultrafiltration (UF) membrane were applied. As a result, the UF membrane indicated the highest flux recovery ratio (FRR) for pineapple fruit juice wastewater relative to the other wastewaters. Soft drink wastewater had the maximum permeability and FRR for MF membrane due to low turbidity of the feed and low interaction with MF membrane composition, whereas this wastewater showed a lower permeability and FRR in the UF membrane, implying an effective interaction between the residual soluble microbial products and the UF membrane composition. Both membranes showed almost the same performance for amoxicillin wastewater

Current progress on removal of recalcitrance coloured particles from anaerobically treated effluent using coagulation–flocculation

The palm oil industry is the most important agro industries in Malaysia and most of the mills adopt anaerobic digestion as their primary treatment for palm oil mill effluent (POME). Due to the public concern, decolourisation of anaerobically treated POME (AnPOME) is becoming a great concern. Presence of recalcitrant-coloured particles hinders biological processes and coagulation–flocculation may able to remove these coloured particles. Several types of inorganic and polymers-based coagulant/flocculant aids for coagulation–flocculation of AnPOME have been reviewed. Researchers are currently interested in using natural coagulant and flocculant aids. Modification of the properties of natural coagulant and flocculant aids enhanced coagulation–flocculation performance. Modelling and optimization of the coagulation–flocculation process have also been reviewed. Chemical sludge has the potential for plant growth that can be evaluated through pot trials and phytotoxicity test

Palm oil mill effluent digestion in an up-flow anaerobic sludge fixed film bioreactor

Theeffectoforganic loadingrate (OLR) providedby hydraulic retention time(HRT) and influent chemical oxygen demand (CODin) on the performance of an up-flow anaerobic sludge fixed film (UASFF) bioreactor treating palm oil mill effluent (POME) was studied. Anaerobic digestion of POME was modeled and analyzed with two variables i.e. HRT and CODin. Experiments were conducted based on a general factorial design and analyzed using response surface methodology (RSM). The region of exploration for digestion of POME was taken as the area enclosed by HRT (1 to 6 days) and CODin (5260 to 34725 mg/L) boundaries. A simultaneous increase of the variables determined a decrease of COD removal efficiency, SRT and SRF and an increase of COD removal rate, VFA/Alk., CO2 fraction in biogas, methane production rate. The best COD removal rate for POME treatment in an anaerobic hybrid reactor has obtained at an OLR of 17.6 g COD/l.d while it was at 26.21 g COD/l.d (Corresponds to CODin of 26210 mg COD/l and HRT of 1 day) in the present study. Minimum and maximum SRT values obtained were 16 and 1904 days at OLR of 34.73 and 0.88 g COD/l.d, respectively. The present study provides valuable information about interrelations of quality and process parameters at different values of the operating variables

Influence of thermal and chemical pretreatment on structural stability of granular sludge for high-rate hydrogen production in an UASB bioreactor

Fermentation of organic waste materials presents an alternate route instead of photosynthetic and chemical routes for hydrogen production. Low yield of biohydrogen production is the major challenge in the fermentative hydrogen-producing technology. Improvement of fermentation process by various sludge pretreatment methods is one of the ways that have been applied to boost hydrogen productivity. This study sheds new light on the impact of thermal and chemical pretreatments on the hydrogen-producing granular sludge morphology and strength as well as up-flow anaerobic sludge blanket (UASB) reactor performance treating palm oil mill effluent (POME). Thermal pretreatment showed devastating effects on the morphological and structural characteristics of the granules. However, the chemically pretreated granules remained structurally stable and relatively undamaged. The thermal pretreatment increased the cumulative hydrogen production by 40% and 76% over chemical pretreatment and control test (untreated), respectively