Adaptation of batch experiment data to the design of anaerobic continuous digesters

The design of a continuously stirred tank reactor (CSTR) for the processing of municipal solid waste (MSW) to produce biogas required an investigation of the kinetic parameters of the substrate relevant to the determination of reactor dimensions. The determination of these parameters is usually complicated with an experimental CSTR set-up. Therefore, it is preferred to use a batch-scale experimentation to determine the parameters. However, because of the differences between the batch and continuous processing, the batch experimentation parameters cannot be directly applied to the design of the CSTR. Some previous researchers had made a comparative evaluation of the batch and continuous processing systems, and developed a procedure for adapting batch experimentation data to the design of continuous reactors. In this study, laboratory scale batch digesters were used to determine the kinetic parameters of MSW, with  the said procedure, they were adapted to the design of a CSTR for the digestion of MSW in the production of biogas. This paper presents a successful application of batch experimentation data on MSW to the design of a CSTR for MSW in Port Harcourt metropolis, Nigeria

Environmental Crises in Government-controlled Municipal Solid Waste Management in Rivers State, Nigeria

This paper investigated and evaluated the crises that rocked municipal solid waste management (MSWM) in Port Harcourt, the capital city of Rivers State, Nigeria, as the State transited from one governmental regime to another in 2015. The city witnessed unprecedented increase in waste heaps at every nook and cranny, that were unattended to for a relatively long time. The investigation used field data and literature information from various stakeholders, including personal interviews and participant observations. Field reports and interview responses were analysed using simple mathematical relations and global best environmental practices. It was found that overbearing political interests and deficiency of funds elicited the crises. The critical aspects of MSWM in the metropolis are undertaken by contractors who depend almost entirely on government funding, making the processes not self-sustaining, hence a transitional defect in the State jolted the stability of the MSWM fabric. The existing practice of simply collecting waste from streets and disposing has not encouraged self-funding for the waste management sector. Formulation and implementation of appropriate policies and creation of incentives for green management; and introduction of friendly advance disposal fees may be feasible options in the solution to the challenges of MSWM in the metropolis. Keywords: Environmental crises, municipal solid waste, political interest, government-controlled, transitio

Perceived Macroeconomic Factors and Stock Market Capitalization: Experience from the Nigerian Economy Perspective

The interference of perceived macroeconomic variables on stock market performance despite the continuous management of monetary and fiscal policies has raised eyes brow and motivated for this study. The purpose of this study is to examine the magnitude of relationships of the perceived macroeconomic factors and stock market performance during its interface. Therefore this study evaluated the prevailing interrelationships between Nigerian Stock Market Performance and the Perceived Macroeconomic factors of Exchange rate, External reserves, Gross Domestic Product, Inflation rate and Interest rate. The data information is sourced from Central Bank of Nigeria statistical bulletin between 1985 and 2014. The Augmented Dickey Fuller, Johansen Co-integration, and the Error Correction Models were employed. The results of the ADF revealed that all variables were stationery at first level differences. The results in Johansen Co-integration indicate a significant long run relationship between three studied variables that relate with the Nigeria Stock Market performance. Further, ECM results reported that GDP remains significant variable that respond to stock market performance positively, while inflation responded negatively, while interest rate and external reserves are shown to responding and adjusting to trends in Stock Market Capitalization. And market capitalization and exchange rate are operating independent of each other. The study concluded that GDP and inflation rate constitute the significant policy variables of interest to manage and promote the desired performance of Nigerian stock market. The study recommend for increase of output of goods and services, and adequate management of inflation rate

Effect of Pre-treated Oil-based Drill Cuttings on the Compressive Strength of Sandcrete Blocks

This study examines the drill cuttings on the compressive strength of mortar blended with thermally desorbed drill cuttings and Portland-limestone cement grade 42.5R. The thermally desorbed drill cuttings was used as a partial substitute for Portland-limestone cement. Replacement levels of 0, 5, 10, 15, 20 and 25% were used. The chemical oxide composition, initial and final settings times and the compressive strengths of the blended mortar were determined at curing period of 7 days, 28 days and 90 days respectively. The ANOVA analysis showed that the replication means are not significantly different at 5% probability level, while the coefficient of variability obtained is 10.9% which is within the acceptable limit of less than 20%. Also, the results showed that the treatment means are significantly different at 5% probability level and within the acceptable limit of coefficient of variability which is the degree of precision with which the treatments were compared. Hence, this indicates that the 95% probability that the conclusion of the treatment mean being different is correct, keeping other experimental variables constant. Therefore, partial replacement of cement with the pretreated oil based drill cuttings at different replacement levels has a significant effect on the compressive strength of the sandcrete blocks produced

Comparative Evaluation of Batch and Continuous Anaerobic Digesters in Biogas Production from Municipal Solid Waste using Mathematical Models

An investigation was conducted into the suitability of either of the batch or continuous (CSTR) digesters for anaerobic degradation of municipal solid waste (MSW) in the production of biogas. Mathematical models were developed for the design and evaluation of the two systems. The development of the models was based upon a material balance analysis of the digesters'operation. A Microsoft Visual Basic Version 6.0 Programme was developed for the solution ofthe model equations, and the digesters' operations simulated over a range of percentage total solids (PTS) concentration of 4-10% for the CSTR and 4-30% for the batch digester, and fractional conversion of 0.2-0.8. The results of the simulation show that although the amount of methane (0.0764m3) produced per unit volume of the batch digester is about 4 times less than the amount (0.284m3) per unit volume of the CSTR, the cost per unit volume of the batch digester ($5.98) is 6 times less than that of the CSTR ($33.8), suggesting that the overall cost of producing gas with the batch digester would be more economical. So, it was deduced that the batch digester is better suited for the digestion of MSW for biogas production, compared to the CST

Performance of irrigated maize in a crude-oil polluted soil remediated by three nutrients in Nigeria's Niger Delta

An in-situ simulated crude-oil polluted soil was remediated for 8 weeks by three different nutrients, and then used to plant maize (Farz 26) with a growth period of 14 weeks, with an irrigation depth of 4mm/day. Remediation consisted of the application of 16.667, 22.222, and 27.778 t/ha of NPK (15:15:15) fertilizer, spent mushroom substrate (SMS), and pig slurry (PS) to the polluted soil, laid out in randomized complete block design, with three replications, including a control that was neither polluted nor treated. Physico-chemical and microbial properties of the soil before and during remediation, and growth parameters of the maize were determined. Results indicated that 8 weeks after remediation, 27.778 t/ha of NPK, PS, and SMS reduced total hydrocarbon content (THC) by 87.3, 91.2, and 88.6% respectively. For maize, 14 weeks after planting resulted in a yield of 1.11, 1.20, and 1.17 t/ha from the soil remediated by 27.778 t/ha of NPK, PS, and SMS respectively, while the control yielded 2.58 t/ha. The difference in yields between the control and the remediated soils was significant at 5% level. The result indicated a 53.5% reduction in yield mainly due to the non-restoration of the soil to its original status

Effect of Total Solids Concentration of Municipal Solid Waste on the Biogas Produced in an Anaerobic Continuous Digester

Municipal Solid Waste (MSW) contains a relatively large amount of organic matter, which decomposes by the actions of microorganisms under anaerobic conditions to produce biogas. The total solids (TS) concentration of the waste influences the pH, temperature and effectiveness of the microorganisms in the decomposition process. This work investigated various concentrations of the TS of MSW in an anaerobic continuously stirred tank reactor (CSTR) and the corresponding amounts of biogas produced, in order to determine conditions for optimum gas production. Five laboratory-scale anaerobic batch digesters of 5 litres volume each were set up for the digestion of 2kg of shredded MSW diluted to a %TS concentration of 26.7%. The results from the batch experimentation were adapted to the design of a CSTR for the digestion of MSW. The CSTR was simulated over a range of %TS concentration of 4-10, at a maximum fractional conversion of 0.8 to cater for system inefficiencies. Mathematical models were developed for the process and solved using the Microsoft Visual Basic version 6.0 Programme. The results show the amount of biogas produced as a power function of the %TS concentration, indicating that as the process continues, a time comes when any marginal increase in the %TS concentration would no longer contribute to the increasing volume of biogas produced. The results further show that, given the limiting upper boundary of the %TS concentration, optimum biogas production in a CSTR digesting MSW cannot be ascertained with the concentration of the %TS alone

BIOBURDEN (QUALITY) OF DIFFERENT DRINKING WATER SAMPLES

ABSTRACT The bacteriological quality of various drinking water samples of treated pipe-borne (tap) water, borehole water and well water collected from five (5) locations within "Town" Area of Port Harcourt in Nigeria was evaluated using the standard plate count method and the most probable number (MPN) technique. The temperature and pH mean values recorded ranged from 22.2°C ± 1.48°C to 23.4°C ± 1.95°C and from 7.16 ± 0.055 to 7.36 ± 0.055 respectively. Total aerobic heterotrophic bacterial counts ranged from 7.72 x 10 3 cfu/ml ± 6.42 x 10 3 cfu/ml to 12.2 x 10 3 cfu/ml ± 7.29 x 10 3 cfu/ml. While the total coliform and faecal coliform MPN index/100ml ranged from 0 to 1800+ and from 0 to 900 respectively. Analysis of variance (ANOVA) using F-test showed that there was significant difference at p ≤ 0.01 in pH and in faecal coliform MPN and at p≤0.05 in the other parameters determined. The bacteria isolated include Chromobacterium spp., Corynebacterium spp., Escherichia coli, Enterobacter spp., Klebsiella spp., Salmonella spp., Shigella spp., Staphylococcus spp., Streptococcus spp., and their percentages ranged from 5% to 15%. The order of decreasing bacteriological quality of samples is treated tap water > borehole water > well water. The presence of E. coli and enteric pathogens such as Shigella, Enterobacter etc., indicated the contamination of the various water sources with faecal matter implying that they are not suitable for drinking

Effect of graded compaction of tilled and untilled sandy loam soil on growth and yield of maize

The performance of maize on tilled and untilled sandy loam soil, under different levels of compaction of 0, 2, 4 and 6 tractor-wheel passes in a humid tropical environment was investigated with a Massey Ferguson (MF) 90-disc plough, mounted on an MF 260 tractor. The experimentation had different aspects, respectively conducted in the field and laboratory, at the Rivers State University, Port Harcourt, Nigeria. The experimental field was a 72 m2 plot of land, which was left fallow for two years before the investigation. The plot was sub-divided into five experimental subplots of 9 m2 each, numbered 1 to 5, with a furrow spacing of 0.5 m. Soil samples were taken randomly at a depth of 0.3 m for the determination of the soil physical properties. After the compaction treatments, maize seeds were manually planted at a depth of 0.05 m and the growth and yield of the maize monitored over a period of fourteen weeks after planting. The investigation showed that the maize crop performed optimally on subplot (2), which was tilled and un-compacted, with a dry matter content of 2,859 kg ha-1, while the least performance was on subplot (1) that was untilled and un-compacted, with a dry matter content of 1,192 kg ha-1. Therefore, this research establishes that, with the agricultural practice of shifting cultivation, sandy loam soil in a humid tropical region requires a minimum level of tillage to achieve optimal yield of maize crop