Research Publications (Water and Wastewater Technology)

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Anaerobic digestion model to enhance treatment of brewery wastewater for biogas production using UASB reactor
(Springerlink, 2015) Enitan, Abimbola Motunrayo; Adeyemo, Josiah; Swalaha, Feroz Mahomed; Bux, Faizal
Biogas produced from an upflow anaerobic sludge blanket (UASB) reactor is a clean and an environmentally friendly by-product that could be used to meet partial energy needs. In this study, a modified methane generation model (MMGM) was developed on the basis of mass balance prin-ciples to predict and increase methane production rate in a UASB reactor during anaerobic fermentation of brewery wastewater. Model coefficients were determined using the da-ta collected from a full-scale reactor. The results showed that the composition of wastewater and operational conditions of the reactor strongly influence the kinetics of the digestion process. Simulation of the reactor process using the model was used to predict the effect of organic loading rate and temperature on methane production with an optimum methane production at 29 °C and 8.26 g COD/L/day. Methane produc-tion rate increased from 0.29 to 1.46 L CH4/g COD, when the loading rate was increased from 2.0 to 8.26 g COD/L/day. The results showed the applicability of MMGM to predict usable methane component of biogas produced during anaerobic digestion of brewery wastewater. This study would help industries to predict and increase the generation of renewable energy by improving methane production from a UASB reac-tor. To the best of our knowledge, MMGM is the first reported developed model that could serve as a predictive tool for brewery wastewater treatment plant available in the literature.
Biodiesel production potential of wastewater microalgae chlorella SP. under photoautotrophic and heterotrophic growth conditions
(BAAR, 2012-10) Viswanath, Buddolla; Bux, Faizal
In the present study, a microalgae (Chlorella sp.) isolated from wastewater pond has been studied in both photoautotrophic and heterotrophic growth conditions in bioreactor to evaluate the cell growth rate and lipid content for biodiesel production. Maximum amount of biomass was recovered from the bioreactor of Chlorella sp. grown under heterotrophic growth conditions with 8.90 gL-1 compared to photoautotrophic growth conditions, which was almost 3.6, fold lesser than the former. Heterotrophic growth of Chlorella sp. resulted in the accumulation of high lipid content in cells compared autotrophic growth by enhancing lipid production by 4.4 fold. The results suggested that heterotrophic growth of microalgae is an efficient method for the production of biomass and high lipid content in the cells, which can reduce the cost of microalgal biomass production and microalgal oil production. The quality of the oil produced from the cells of heterotrophic growth is also superior compared the oil from photoautotrophic growth.
Evaluation of operating conditions for sustainable harvesting of microalgal biomass applying electrochemical method using non sacriﬁcial electrodes
(Elsevier, 2015) Misra, Rohit; Guldhe, Abhishek; Singh, Poonam; Rawat, Ismail; Stenström, Thor-Axel; Bux, Faizal
The efficient harvesting of microalgae is considered to be one of the challenging steps of algal biofuel production and a key factor limiting the commercial use of microalgae. To overcome the limitation of metallic electrodes depletion, the application of non-sacrificial electrode was investigated for the electrochemical harvesting (ECH) of microalgae. The effect of applied current, addition of electrolyte and initial pH were parameters investigated. The highest recovery efficiency of 83% was obtained for Scenedesmus obliquus at 1.5 A, initial pH 9 and 6 g L−1 NaCl with power consumption of 3.84 kWh kg−1. Recovery efficiency of ECH process was comparable to literature reported centrifugation, filtration and chemical flocculation techniques but with a much lower power consumption. The ECH process with addition of electrolyte enhanced the lipid extraction by 22% without any adverse effects. The ECH process with non sacrificial carbon electrodes could be a possible harvesting step at commercial scale microalgal biomass production.
Evaluation of phytotoxicity effect on selected crops using treated and untreated wastewater from different configurative domestic wastewater plants
(Taylor and francis Online, 2016) Ravindran, B.; Kumari, Sheena K.; Stenström, Thor-Axel; Bux, Faizal
This study investigated the phytotoxicity effect of untreated and treated wastewater collected from two different configurations of domestic wastewater treatment plants in South Africa. The phytotoxicity effect on vegetable seed growth was studied in terms of germination index (GI), relative seed germination (RSG) and relative root elongation (RRE) using four commercial crop varieties, viz., tomato (Lycopersicon esculentum), radish (Raphanus sativus), carrot (Daucus carota) and onion (Allium cepa). According to phyototoxicity limits, 80% germination and above is regarded as non-toxic and less than 50% GI is regarded as highly toxic and not suitable for agricultural purposes. In our study, seeds were irrigated with concentrations of 25%, 50%, 75%, 100% of treated effluent (TE) and untreated effluent (UTE). The TE results were best with the highest GI (%) recorded as tomato, 177; carrot, 158.5; onion, 132; and lettuce, 124. The results of this study indicate that TE showed no phytotoxicty effects and recorded above 80% GI. The UTE irrigated crops reached a GI of only 50% and above which is clear evidence of the beneficial effect of waste water treatment. The overall results confirmed that treated wastewater has a beneficial effect on agricultural crops and can be used as a liquid fertilizer.
Pathways of 3-biofules (hydrogen, ethanol and methane) production from petrochemical industry wastewater via anaerobic packed bed bafﬂed reactor inoculated with mixed culture bacteria
(Elsevier, 2016) Elreedy, Ahmed; Tawfik, Ahmed; Enitan, Abimbola Motunrayo; Kumari, Sheena K.; Bux, Faizal
Simultaneous production of 3-biofuels (hydrogen, ethanol and methane) as by-products of the biodegra-dation of petrochemical wastewater containing MEG via anaerobic packed bed bafﬂed reactor (AnPBBR), was extensively investigated. A four-chambered reactor supported by polyurethane sheets, was operated at a constant hydraulic retention time (HRT) of 36 h and different organic loading rates (OLRs) of 0.67, 1, 2 and 4 gCOD/L/d. The maximum speciﬁc H2 and CH4 production rates of 438.07 ± 43.02 and 237.80 ± 21.67 ml/L/d were respectively achieved at OLR of 4 gCOD/L/d. The residual bio-ethanol signif-icantly increased from 57.15 ± 2.31 to 240.19 ± 34.69 mg/L at increasing the OLR from 0.67 to 4 gCOD/L/d, respectively. The maximum MEG biodegradability of 98% was attained at the lowest OLR. Compartment-wise proﬁles revealed that the maximum H2 and ethanol production were achieved at HRT of 9 h (1st compartment), while the CH4 production was peaked at HRTs of 27 and 36 h (last two compartments). Kinetic studies using Stover–Kincannon and completely stirred tank reactor (CSTR) in series models were successfully applied to the AnPBBR overall and compartment-to-compartment performance, respectively. The economic evaluation strongly revealed the potentials of using AnPBBR for simultaneous treatment and bio-energy production from petrochemical wastewater as compared to the classical anaerobic bafﬂed reactor (ABR). Microbial analysis using Illumina MiSeq sequencing showed a diversity of bacterial com-munity in AnPBBR. Proteobacteria (36.62%), Firmicutes (20.85%) and Bacteroidetes (3.44%) were the most dominant phyla.
Polyhydroxyalkanoates production from fermented paperboard mill wastewater using acetate-enriched bacteria
(Springer-Verlag Berlin Heidelberg, 2017) Farghaly, Ahmed Mustafa; Enitan, Abimbola Motunrayo; Kumari, Sheena K.; Bux, Faizal; Tawfik, Ahmed
The aim of the study was to investigate the use of dark fermented paperboard mill wastewater (PMW) containing volatile fatty acids for polyhydroxyalkanoates (PHA) production. Six sequencing batch reactors (SBRs) were initially fed with synthetic feed containing acetate and operated at different organic loading rates (OLRs) of 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 gCOD l-1 day-1 for PHA-storing bacteria enrichment. The maximum PHA content and yield (YPHA/S) were 67.44 ± 5.88 % and 0.45 ± 0.39 C-mol C-mol-1 at OLR of 1.5 gCOD l-1 day-1, respectively. The synthetic feed was replaced by dark fermented PMW efﬂuent rich in acetate, butyrate, propionate, and lactate at the accumulation stage resulting in a PHA content and yield of 58.57 ± 4.02 % and 0.46 ± 0.09 C-mol C-mol-1, respectively. The maximum speciﬁc PHA production rate max ) amounted to 0.29 ± 0.1 C-mol C-mol-1 X-1 h-1.(qPHA Illumina MiSeq sequencing of bacterial 16S rRNA gene showed that Proteobacteria and Bacteroidetes increased from 37.4 to 77.6 % and from 2.49 to 17.66 % at enrich-ment and accumulation stages, respectively. Actinobacteria (15.44 %), Chloroﬂexi (8.15 %), Planctomycetes (7.46 %), and Acidobacteria (6.0 %) were detected at the enrichment SBRs.
Synthesis of biodiesel from Scenedesmus sp. by microwave and ultrasound assisted in situ transesterification using tungstated zirconia as a solid acid catalyst
(Elsevier, 2014-05-20) Guldhe, Abhishek; Singh, Bhaskar; Rawat, Ismail; Bux, Faizal
Oleaginous Scenedesmus sp. was cultivated phototrophically in an open pond for biofuels production. The culture was harvested and subsequently dewatered and dried. The chemical properties of the Scenedesmus sp. lipids were determined as per standard ASTM methods. Biodiesel was synthesized by in situ transesteriﬁcation from dried biomass using microwave and sonication techniques with tungstated zirconia (WO3/ZrO2) as a solid acid catalyst. In situ transesteriﬁcation allowed minimizing the requirement of solvents by merging the two steps (i.e. extraction of lipid and conversion to biodiesel) to a single step. The use of a solid catalyst effectively reduces the puriﬁcation cost of biodiesel due to ease of separation and potential for reuse. The conversion of Scenedesmus sp. lipids to biodiesel was determined by GC. Box–Behnken design was used for optimization of the variables to optimize the biodiesel yield and conversion. The efﬁciency of the two processes was compared.