• Energy Research

Abstract A start-up study was conducted to produce biohydrogen and biomethane from Palm Oil Mill Effluent (POME) using a two-stage up-flow anaerobic sludge fixed-film (UASFF) bioreactor. 100% molasses was used to start the system, and POME was added at 10% increments until it reached 100% after 59 days. During this period of continuous operation, the HRT and temperature were adjusted in order to optimize the condition for biogas production. Hydrogen and methane gas production fluctuated between 53–70% and 90–95%, respectively, in the last four days of operation (days 56–59), with POME percentage being increased from 70% to 100% (30%–0% molasses). Using 100% raw POME led to a total COD removal of 83.70%, average gas production rates of 5.29 L H 2 d −1 (57.11% H 2 ) and 9.60 L CH 4 d −1 (94.08% CH 4 ), in their respective units. This output is comparable to, if not better than using 100% molasses as substrate. This work concludes that based on the relative consistency of biogas production on days 56–59, the two-stage UASFF bioreactor operating at a final HRT of 4 h and temperature of 43 °C has taken a period of two months for start-up.

Lignocellulosic biomass has been widely recognised as a potential low-cost source for the production of high added value materials and proved to be a good precursor for the production of activated carbons. One of such valuable biomasses used for the production of activated carbons is palm shell. Palm shell ( endocarp) is an abundant by-product produced from the palm oil industries throughout tropical countries. Palm shell activated carbon and palm shell carbon molecular sieve has been widely applied in various environmental pollution control technologies, mainly owing to its high adsorption performance, well-developed porosity and low cost, leading to potential applications in gas-phase separation using adsorption processes. This mini-review represents a comprehensive overview of the palm shell activated carbon and palm shell carbon molecular sieve preparation method, physicochemical properties and feasibility of palm shell activated carbon and palm shell carbon molecular sieve in gas separation processes. Some of the limitations are outlined and suggestions for future improvements are pointed out.

In recent years, source-separated human urine has been highlighted as an effective resource for energy and nutrient recovery. However, even though several technologies exist for resource recovery, they have not been widely implemented. Among these technologies, bioelectrochemical systems (BESs) hold promise as technically and economically interesting alternatives for sustainable resource recovery from source-separated urine. Here, we review the resource recovery performance of BESs, including microbial fuel cells (MFCs) and microbial electrolysis cells (MECs), fed with source-separated urine over the past decade, and suggest an effective path forward toward their widespread implementation.

The present work is a study of the performance and effect of operational parameters on biohydrogen production from palm oil mill effluent by dark fermentation in batch mode. The process parameters examined are pH (5, 5.5, and 6), temperature (30, 35, and 40 °C), substrate concentration (5000, 12 500, and 20 000 mg L−1) and inoculum volume (20, 25, and 30 mL). The inoculum concentration prepared was 10 000 mg L−1 volatile suspended solids. The experiments were designed by response surface methodology (RSM). The highest chemical oxygen demand (COD) removal, hydrogen percentage (H2%) and hydrogen yield (HY) obtained were 58.3%, 80%, and 4.83 mol H2/mole of COD consumed, respectively. Based on the experimental data obtained with the RSM design, gene expression programming (GEP) was developed to predict the COD removal, hydrogen production, and hydrogen yield as process responses. The projected models were assessed based on the correlation coefficient (R2), root mean square error, mean absolute relative error, scatter index, and BIAS. The results demonstrate that the GEP model outperformed the RSM model and was superior in predicting the response variables. Partial derivative sensitivity analysis was also employed to assess the effect of each variable on COD%, H2%, and HY prediction. The prediction uncertainty for COD%, H2%, and HY was quantified, and the results were ±0.11, ±0.17, and 0.015, respectively. According to the results, the GEP model is more efficient than the RSM model in predicting the experimental data for biological hydrogen production in the dark fermentation process.

Response surface methodology was applied to optimize the removal of lead ion by Aspergillus niger in an aqueous solution. Experiments were conducted based on a rotatable central composite design (CCD) and analyzed using response surface methodology (RSM). The biosorption process was investigated as a function of three independent factors viz. initial solution pH (2.8-7.2), initial lead concentration (8-30 mg/l) and biomass dosage (1.6-6 g/l). The optimum conditions for the lead biosorption were found to be 3.44, 19.28 mg/l and 3.74 g/l, respectively, for initial solution pH, initial lead ion concentration and biomass dosage. Lead biosorption capacity on dead A. niger fungal biomass was enhanced by pretreatment using NaOH. Under these conditions, maximum biosorption capacity of the biomass for removal of lead ions was obtained to 96.21%. The desirability function was used to evaluate all the factors and response in the biosorption experiments in order to find an optimum point where the desired conditions could be obtained. The A. niger particles with clean surface and high porosity may have application as biosorbent for heavy metal removal from wastewater effluents.

Abstract In this study, wastewater treatment was destined for generation of electricity and hygienic water by an innovative integrated microbial fuel cell – membrane separation process (MFC-MSP). An optimal antifouling nanofiltration membrane (blended with O-carboxymethyl chitosan bound Fe3O4 magnetic nanoparticles (CC Fe3O4 NPs)), an antifouling ultrafiltration (UF) membrane (blended with polycitrate-alumoxane nanoparticle (PC-A)) and a high efficiency proton exchange membranes were applied in MSP and MFC processes. Firstly, the performance of MFC unit under different operating conditions of reaction time (RT), mixed liquor suspended solid (MLSS) concentration and influent chemical oxygen demand (COD) concentration was investigated in terms of COD removal efficiency and power generation for synthetic dairy wastewater treatment. The experiments were modeled using response surface methodology (RSM). The results indicated that by increasing in RT and CODin concentration, the COD removal was decreased. Also, the high concentration of MLSS in anodic chamber led to high COD removal efficiency. By increasing of MLSS beyond 3000 mg/L, the maximum power generation was decreased that reveals an adverse impact of biofouling on membrane performance. After primary treatment in anodic chamber of MFC at optimum condition, the anodic chamber effluent was passed through the membranes in two modes, direct nanofiltration (NF) membrane and UF-NF membranes in series. The results indicated that the UF membrane alleviated the organic loading of NF membrane by 72% relative to the direct NF filtration. The permeation flux shows a sustain performance of the NF when is coupled with UF membrane.a.

This work is a study of the performance and effect of operational parameters on biohydrogen production from palm oil mill effluent by dark fermentation in batch mode. The tests were conducted with samples prepared in 150 mL bottles using a shaker at 150 rpm. Response surface methodology was applied to investigate the influence of the four significant independent parameters viz. pH (5, 5.5, and 6), temperature (30°C, 35°C, and 40°C), substrate concentration (5,000, 12,500, and 20,000 mg L –1 ) and inoculum–substrate ratios of 2, 0.8, and 0.5 (expressed as volatile suspended solid (VSS) basis) with the inoculum concentration of 10 g L –1 VSS on biohydrogen production. All the experiments were analyzed at the incubation time of 8, 16, and 24 h. Upon seeing each interval, the results were compared. The highest chemical oxygen demand (COD) removal, the hydrogen content in the biogas as hydrogen percentage (H 2 %), and hydrogen yield (HY) were obtained 58.3%, 80%, and 3.63 mol H 2 mol –1 glucose, respectively, at 24 h incubation time. An overlay study was done to find an overall optimization of the parameters. The optimized conditions were COD removal 49%, HY 3.2 mol H 2 mol –1 glucose, and hydrogen percentage 80%. Also, the Monod model was studied to calculate the kinetics constants of the maximum substrate utilization rate (U max ) and half-velocity K s which are found to be 0.261 g L –1 d –1 and 0.349 mg L –1 , respectively. © 2019 Desalination Publications. All rights reserved.

Abstract 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.

In this study, performance and kinetic analysis of carbon and nutrients removal in an up‐flow aerobic/anoxic sludge bed (UAASB) bioreactor for the treatment of an industrial estate wastewater was investigated. The performance of the reactor was evaluated as a function of two variables, including hydraulic retention time (HRT) of 4, 8, and 12 h and aeration time of 40 and 60 min/h. To obtain the kinetic coefficients, mass balance, first‐order, second‐order, and Stover–Kincannon models were employed. From the mass balance model, growth yield (Y), microbial decay rate (Kd), were found to be 0.161 g volatile suspended solid (VSS)/g chemical oxygen demand (COD), 0.039 1/d, respectively, whereas for first‐order model (K1) was 4.56 1/d. The constant values for Stover‐Kincannon model were obtained as half‐velocity constant (KB = 9.82 g/L) and maximum total substrate removal rate constant (Umax = 8.47 g/L d). © 2014 American Institute of Chemical Engineers Environ Prog, 33: 1220–1228, 2014