American Scientific Research Journal for Engineering, Technology, and Sciences, 2020
A multivariate technique was used to optimize methane production from anaerobic digestion of macr... more A multivariate technique was used to optimize methane production from anaerobic digestion of macroalgae under mesophilic and thermophilic conditions. To evaluate the effects and interaction of three reaction variables: COD, VFA, and ammonia on methane production, their data recorded in a time order were subjected to fit and multiple regression analysis, which generated a second order quadratic polynomial equation used to predict the optimized methane production. The ANOVA results showed the developed model for the mesophilic (p< 0.003) and thermophilic (p< 0.000) reactors are significant. Their R2 values of 0.97 and 0.99 suggest it was suitable for interpreting the experimental data set and adjusted R2 of (0.91 and 0.97) indicates good regression models. The interaction terms for mesophilic and thermophilic reactors, has a positive influence on methane production compared to other terms. The model predicted the optimal reactors conditions, derived as X1: COD = 6.6 g L-1, X2: ...
In the absence of pressure gradients, conditions prevalent in the batch experiments, gas –phase d... more In the absence of pressure gradients, conditions prevalent in the batch experiments, gas –phase diffusion dominates migration of volatile pollutants in the unsaturated zone. Gas –phase diffusion in the unsaturated zone is affected by partitioning into soil-water, onto air-water and into or onto solid. The process spreads only the contaminants in the gas phase where contaminants with low mass fraction fa in the soil gas diffuse more slowly depending on the soil and chemical properties on the diffusing substance. This study shows Non-aqueous phase liquids (NAPL) compounds with higher mass fraction (Isooctane (0.82), n-hexane (0.78), methylcyclopentane (0.54)) diffuse to a longer distance (1.75m, 1.30m, 1.50m) than those with low mass fraction (toluene (0.04), m-xylene (0.04), octane (0.09), (60m, 60m and 51 m respectively) from a source zone. The diffusion coefficient D’ calculated was also higher for these compounds; 0.05, 0.05, 0.05 and 0.00, 0.00 and 0.001 respectively. At transien...
University of Port Harcourt, Dept. of Civil and Environmental Engineering Choba, Nigeria --------... more University of Port Harcourt, Dept. of Civil and Environmental Engineering Choba, Nigeria ----------------------------------------------------------------------***--------------------------------------------------------------------Abstract This study examined anaerobic digestion of mono and co-digestion of Laminaria digitata (LD) with a simulated food waste (SFW) in a continuous reactor experiments. Different mix ratios of LD and SFW, namely, LD100:0%, LD90:10%, LD75:25%, LD50:50% were assessed. Results indicated that reactor, LD90:10% was found to be optimal for the highest cumulative methane production (175 ± 0.17 L/ reactor) after 85 days and achieved a maximum biomethane efficiency factor BEF (0.93) at an OLR 4 gVS.L-1.d-1. The mono-digestion of LD100:0% in continuous reactors was characterized by the accumulation of high total volatile fatty acids (tVFA), reduced pH, and an increased FOS: TAC ratio as the OLR was increased, which led to reactor failure.. Co-digestion of L digita...
This study investigates the effect of trace element supplementation (TES) on mesophilic anaerobic... more This study investigates the effect of trace element supplementation (TES) on mesophilic anaerobic digestion treating Laminaria digitata (LD) in both batch and continuous (CSTR) reactors. Two set of Experiment 1 and 2 (batch and continuous) reactors were carried out with and without trace element addition, and their performance compared. In Experiment 1, five (batch 500 ml and 1L CSTR) reactors were operated with the addition of metals mixtures in Reactors (TES 1–4) and Reactor (TES 0) as control without addition. The results of first batch test (BT 1) show that TES 1-4 reactors achieved an increase in methane yield of between 17-26% compared to the control reactor without TES after 22 days of incubation. In CSTR reactors, the results show that daily trace elements addition with an HRT of 25 days allowed for a stable anaerobic digestion in three different combinations TES 24 at an organic loading rate of 2 gVS.L.d used throughout the experiment, but did not give any advantage over th...
This study describes and evaluates a computational model for biogas production as a function of t... more This study describes and evaluates a computational model for biogas production as a function of time u sing urea, cow and horse dung as inoculums. The inoculums were co-digested with Organic Fractions o Municipal Solid Waste (OFMSW) at room temperature. A series of laboratory experiment s using 1500 ml bio-digester and super saturated sa line water flask were performed in batch operation mode for a period of 46 days. Four (4) batch digesters were utilized ; each contained varying amounts of the inoculums with that of food waste kept constant. Biogas production was measured indirectly by water displacement method. The actual bio-digester potential was determined using the modelled equatio n to adequately describe the cumulative biogas production from thes e digesters (A-D). It was observed that the rates o f removal of biodegradable fractions of the substrate could be o btained by plotting 1/t (lndyt/dt) against 1/t. The results showed that the first order kinetic constant of -0.0114...
American Scientific Research Journal for Engineering, Technology, and Sciences, 2020
A multivariate technique was used to optimize methane production from anaerobic digestion of macr... more A multivariate technique was used to optimize methane production from anaerobic digestion of macroalgae under mesophilic and thermophilic conditions. To evaluate the effects and interaction of three reaction variables: COD, VFA, and ammonia on methane production, their data recorded in a time order were subjected to fit and multiple regression analysis, which generated a second order quadratic polynomial equation used to predict the optimized methane production. The ANOVA results showed the developed model for the mesophilic (p< 0.003) and thermophilic (p< 0.000) reactors are significant. Their R2 values of 0.97 and 0.99 suggest it was suitable for interpreting the experimental data set and adjusted R2 of (0.91 and 0.97) indicates good regression models. The interaction terms for mesophilic and thermophilic reactors, has a positive influence on methane production compared to other terms. The model predicted the optimal reactors conditions, derived as X1: COD = 6.6 g L-1, X2: ...
In the absence of pressure gradients, conditions prevalent in the batch experiments, gas –phase d... more In the absence of pressure gradients, conditions prevalent in the batch experiments, gas –phase diffusion dominates migration of volatile pollutants in the unsaturated zone. Gas –phase diffusion in the unsaturated zone is affected by partitioning into soil-water, onto air-water and into or onto solid. The process spreads only the contaminants in the gas phase where contaminants with low mass fraction fa in the soil gas diffuse more slowly depending on the soil and chemical properties on the diffusing substance. This study shows Non-aqueous phase liquids (NAPL) compounds with higher mass fraction (Isooctane (0.82), n-hexane (0.78), methylcyclopentane (0.54)) diffuse to a longer distance (1.75m, 1.30m, 1.50m) than those with low mass fraction (toluene (0.04), m-xylene (0.04), octane (0.09), (60m, 60m and 51 m respectively) from a source zone. The diffusion coefficient D’ calculated was also higher for these compounds; 0.05, 0.05, 0.05 and 0.00, 0.00 and 0.001 respectively. At transien...
University of Port Harcourt, Dept. of Civil and Environmental Engineering Choba, Nigeria --------... more University of Port Harcourt, Dept. of Civil and Environmental Engineering Choba, Nigeria ----------------------------------------------------------------------***--------------------------------------------------------------------Abstract This study examined anaerobic digestion of mono and co-digestion of Laminaria digitata (LD) with a simulated food waste (SFW) in a continuous reactor experiments. Different mix ratios of LD and SFW, namely, LD100:0%, LD90:10%, LD75:25%, LD50:50% were assessed. Results indicated that reactor, LD90:10% was found to be optimal for the highest cumulative methane production (175 ± 0.17 L/ reactor) after 85 days and achieved a maximum biomethane efficiency factor BEF (0.93) at an OLR 4 gVS.L-1.d-1. The mono-digestion of LD100:0% in continuous reactors was characterized by the accumulation of high total volatile fatty acids (tVFA), reduced pH, and an increased FOS: TAC ratio as the OLR was increased, which led to reactor failure.. Co-digestion of L digita...
This study investigates the effect of trace element supplementation (TES) on mesophilic anaerobic... more This study investigates the effect of trace element supplementation (TES) on mesophilic anaerobic digestion treating Laminaria digitata (LD) in both batch and continuous (CSTR) reactors. Two set of Experiment 1 and 2 (batch and continuous) reactors were carried out with and without trace element addition, and their performance compared. In Experiment 1, five (batch 500 ml and 1L CSTR) reactors were operated with the addition of metals mixtures in Reactors (TES 1–4) and Reactor (TES 0) as control without addition. The results of first batch test (BT 1) show that TES 1-4 reactors achieved an increase in methane yield of between 17-26% compared to the control reactor without TES after 22 days of incubation. In CSTR reactors, the results show that daily trace elements addition with an HRT of 25 days allowed for a stable anaerobic digestion in three different combinations TES 24 at an organic loading rate of 2 gVS.L.d used throughout the experiment, but did not give any advantage over th...
This study describes and evaluates a computational model for biogas production as a function of t... more This study describes and evaluates a computational model for biogas production as a function of time u sing urea, cow and horse dung as inoculums. The inoculums were co-digested with Organic Fractions o Municipal Solid Waste (OFMSW) at room temperature. A series of laboratory experiment s using 1500 ml bio-digester and super saturated sa line water flask were performed in batch operation mode for a period of 46 days. Four (4) batch digesters were utilized ; each contained varying amounts of the inoculums with that of food waste kept constant. Biogas production was measured indirectly by water displacement method. The actual bio-digester potential was determined using the modelled equatio n to adequately describe the cumulative biogas production from thes e digesters (A-D). It was observed that the rates o f removal of biodegradable fractions of the substrate could be o btained by plotting 1/t (lndyt/dt) against 1/t. The results showed that the first order kinetic constant of -0.0114...
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