Performance of low pressure reverse osmosis membrane treating synthetic natural organic matter (NOM) and endocrine disrupting chemical (EDC)

The current study describes the performance of low pressure reverse osmosis membrane (LPROM) treating synthetic wastewater containing dichlorodiphenyltrichloroethane, DDT (endocrine disrupting chemical, EDC) and glucose (natural organic matter, NOM) at various operating pressure and pH. The experimental results were compared to a modified design expert model using response surface method (RSM). Results showed up to 94.6% DDT and 85% glucose removal was achieved in the membrane system at an operating pressure and pH of 100 psi and 9, respectively, indicating efficient performance of the system. However, when the membrane system was operated at elevated pressure and low pH (120 psi and pH 5.5), the DDT and glocose removal efficiencies decreased to 91.2 and 75.5%, respectively, indicating operating pressure and pH affected the performance of the system. The design expert analysis for both DDT and glucose showed high removal efficiencies (93.67 and 81.70%) when the LPROM was operated at 114.14 psi, confirming that the LPROM is an excellent system for the treatment of EDC and NOM containing wastewater

The effect of mesophilic and thermophilic temperature on the performance of an up-flow anaerobic sludge bed (UASB) reactor

The performance of an anaerobic reactor depends on various factors such as wastewater composition, organic loading rate (OLR), hydraulic retention time (HRT), seed sludge, temperature, and reactor configuration.In the present study, an up-flow anaerobic sludge bed (UASB) reactor was used for the treatment of synthetic wastewater. Specifically, this study was carried out in order to investigate the effect of temperature on the reactor performance when OLR was gradually increased. The reactor was operated at two different temperatures; mesophilic (37°C) and thermophilic (57°C). The maximum COD removal efficiency of the mesophilic operation was low compared tothe thermophilic(75.3and 81.2% respectively). The volatile acid concentration was 80 mg/L throughout the thermophilic and mesophilic experimental study. The MLVSS/MLSS ratio confirms that the utilization of biomass during the thermophilic operation was high. From the study,it was concluded that temperature plays a major role in anaerobic reactor operation,and thermophilic condition provided better reactor performance

Adsorption of heavy metals from matured leachate by Gracilaria. sp extract

Municipal Solid Waste (MSW) landfill leachate is a serious environmental issue and treated using various methods, mostly involving biological treatment. In the present study, Gracilaria.sp extract was used for the treatment of matured landfill leachate containing heavy metals (As, Fe, Ni, and Cd) and Formaldehyde (FA). Specifically, this study was carried out to investigate the adsorption rate of heavy metals and formaldehyde by Gracilaria.sp extract. Four variants of Gracilaria.sp extract were used in the present investigation; 10, 20, 50, and 100 mg/L. The process performance of the treatment was characterized in terms of pollutant removal before and after the treatment process. Results showed that high adsorption of heavy metals were observed compared to the FA compound. Fe was absorbed at the fastest rate as it was not detected in the leachate sample after day one. The FA was removed completely after ten days at a gel concentration of 100 mg/L. Similar trend was also observed for the Cd where it was completely removed after ten days (at 50 mg/L Gracilaria.sp extract). However, Ni was not removed even after ten days, suggesting more time was required for the treatment process. As was removed in five days at a gel concentration of 50 mg/L

Optimization of methane production process from synthetic glucose feed in a multi-stage anaerobic bioreactor

The biological conversion of biomass into methane during anaerobic digestion has been studied by many researchers in recent years. In this study, optimization of methane composition during chemical oxygen demand removal was observed in a multi-stage Anaerobic Bioreactor. Synthetic glucose was used as a feed substrate, and the reactor was operated at a hydraulic retention time (HRT) of 1–4 d. Complementary experimental and theoretical test procedures were evaluated for methane optimization. The theoretical methane was recorded as 50.13, 50.02, 50.16, and 50.22% for an HRT of 4, 3, 2, and 1 d, respectively. However, the quantity of methane determined experimentally was significantly lower than the theoretical predictions; this was likely due to the microorganism activity in the reactor that may have interfered with the efficiency of the biogas generation. Experimental data showed a decrease in the methane composition (35.4, 21.2, 19.8, and 18.4% for HRT of 4, 3, 2, and 1 d, respectively) in the reactor system. Thus, the theoretical formula and experimental data together provide an alternative method for the evaluation of bioenergy potential in anaerobic digestion

Effect of organic loading rate (OLR) on the performance of modified anaerobic baffled reactor (MABR) supported by slanted baffles

The performance of a modified anaerobic baffled reactor (MABR) treating synthetic wastewater at different organic loading rates (OLRs) was investigated. The MABR was seeded with anaerobic sludge taken from a local municipal wastewater treatment plant and fed continuously with glucose at OLRs of 0.258, 0.787 and 2.471 kgCOD/m3·d at hydraulic retention time (HRT) of 4 d. Results showed that 99.7% chemical oxygen demand (COD) removal was achieved during the OLR of 0.258 kg COD/m3·d. However, when the OLR was increased to 0.787 kgCOD/m3·d, a minor decrease in the COD removal efficiency (95%) was noted. Further increase of the OLR to 2.471 kgCOD/m3·d caused the reactor performance to deteriorate dramatically in a COD removal efficiency of 39.5%. Biogas yield was evaluated for the reactor system and followed the similar decreasing trend (0.542, 0.524 and 0.214 L/g CODremoved for the different OLRs respectively). There were no significant different in the pH profiles (6.71–7.01) during the first two OLRs (0.258 and 0.787 kgCOD/m3·d). However, during the final OLR (2.471 kg COD/m3·d) the pH profile in MABR significantly dropped as low as 4.01. A similar trend was also observed in the volatile fatty acids (VFAs) profile where higher value (2880 mg/l) was found at the highest OLR. The poor performance of the MABR at high OLR signifies that the microorganisms could not metabolise the organic substance and probably need more time for digestion