Green element solutions for inverse groundwater contaminant problems

In this work two inverse methodologies are developed based on the Green element method for the recovery of contaminant release histories and reconstruction of the historical concentration plume distribution in groundwater. Unlike direct groundwater contaminant transport simulations which generally produce stable and well-behaved solutions, the solutions of inverse groundwater contaminant transport problems may exhibit non-uniqueness, non-existence and instability, with escalation in computational challenges due to paucity of data. Methods that can tackle inverse problems are of major interest to researchers, and this is the goal of this work. Basically, the advection dispersion equation which governs the transport of contaminants can be handled by analytical or numerical methods like the Finite element method, the Finite difference method, the Boundary element method and their many variants and hybrids. However, if a numerical method is used to solve an inverse problem the resulting matrix is ill-conditioned requiring special techniques to be employed in order to obtain meaningful solutions. In view of this we explore the Green element method, which is a hybrid technique, based on the boundary element theory but is implemented in an element by element manner. This method is attractive to inverse modelling because of the fewer degrees of freedom that are generated at each node. We develop two approaches, in the first approach inverse Green element formulations are developed, the ill-conditioned matrix that results is decomposed with the aid of the singular value decomposition method and solved using the Tikhonov regularized least square method. The second approach utilizes the direct Green element method and the Shuffled complex evolutionary (SCE) optimization method. Finally, the proposed approaches are implemented to solve typical problems in contaminant transport with analytical solutions besides those that have appeared in various research papers. An investigation on the capability of these approaches for the simultaneous recovery of the source strength and the contaminant concentration distribution is carried out for three types of sources and they include boundary iv sources, instantaneous point sources and continuous point sources. The assessment accounts for different transport modes, time discretization, spatial discretization, location of observation points, and the quality of observation data. The numerical results demonstrate the applicability and limitations of the proposed methodologies. It is found in most cases that the solutions with inverse GEM and the least squares approach are of comparable accuracy to those with direct GEM and the SCE approach. However, the latter approach is found to be computationally intensive

On-Site Sanitation and Its Effects on the Groundwater Resources of Nyali-Bamburi-Shanzu and Diani-Chale, Kenya

This paper has analyzed the effects of on-site sanitation systems on groundwater and the impact this has to public health in the human settlements and tourist establishments of Nyali-Bamburi-Shanzu and Diani-Chale areas –two, very important tourist destinations in the Kenya coast. The pit latrine and septic-tank/soakage pit are the two main systems used for containing human waste in the settlements. These two on-site sanitation systems constitute the main source of potential contamination to groundwater and its consequences in the two areas. Hence, the boreholes and wells in the two study areas were located on a map using a GPS to serve as the sampling points. Water from these sources was analyzed for nutrient and feacal contamination in the laboratory. The nutrient contamination was established through the levels of total ammonia, nitrates/nitrites, and phosphates. These were determined using calorimetric methods; while the 5-tube, 3- dilution, Most Probable Number (MPN) technique was used for the evaluation of the levels of total Coliforms and Escherichia Coli (E-coli) parameters. The study was designed with a strategy that captured the effects and impacts of the contaminants with the varying tourist seasons and rainfall pattern. Results of the study revealed that the level of nutrient and micro-bacteria contamination varied with location, distance, tourist seasons and rainfall pattern relative to the contaminating sources. Water sources located within the human settlements and beach hotels –and within short distances to the contaminating sources exhibited elevated levels of nutrients and micro-bacteria; water sources located down-stream the human settlements revealed even higher contamination levels, indicating more input of nutrients and micro-bacteria probably through underground flow and seepage into the water aquifers –likely through cracks in the coral rock formation characteristic of the two study areas. The results of the study lead to the conclusion that on-site sanitation systems, though sanctioned for human waste disposal, may not be suitable in areas dominated by coral geology basement, particularly so when stringent observance of regulations and standard required in the construction of the waste disposal systems are not adhered to. Out of the conclusion, it is recommended that a shift towards innovative approaches in human waste management need to be advanced and pursued as a matter of policy in environmental management. Keywords: On-site sanitation, water contamination, nutrients, micro-bacteria, Total coliform, E. coli

Dancing to the Tune of Opportunities –Human Settlements Aligned to Share the Jackpot of Kenya’s Coastal Tourism Benefits Spoil the Broth

This paper highlights how human settlements aligned themselves to share the benefits to arise from coastal tourism development in the Kenya coast, but have come to bedevil the industry through poor management of domestic waste. The study area comprised of Nyali-Bamburi-Shanzu and Diani-Chale, which are two important tourist destinations in the country. It attempted to establish population numbers in these habitations, the waste loads generated, and how it was managed. The study was accomplished through field visits, library research and application of the World Health Organization (WHO 1989) rapid assessment methods for land, air and water pollution. The relevant data for assessment was obtained from records of population census, bed nights, occupancy, and the waste disposal methods in use. The study revealed that human settlements aligned themselves in clusters inland, reflecting the clusters of the beach hotels dotting the shore line of the Indian Ocean. Large volumes of domestic waste were being generated in both the human settlements and in the hotels. Management of the waste in the settlements was largely on-site and mixed, through the use of both pit latrines and septic-tank/soakage pit systems in the human settlements, and only through septic-tank/soakage pits in the hotel establishments. None of the settlements had wastewater treatment facilities. Only 5 beach hotels had wastewater treatment plants. While the settlements positioned themselves to benefit from the tourism industry, tapping in business and employment opportunities, the arrangement has seemed to spoil the broth as the settlements came to be the main source domestic waste affecting environmental quality and undermining tourism growth and sustainability. Also, through the large number of visitors, during the peak tourist periods, the beach hotels themselves have come contribute to large waste generation. On-site sanitation, it is concluded, is not appropriate for managing domestic waste in coastal areas dependent on good quality environmental to flourish the tourism economic sector. Tourism thrives in areas where the environment is aesthetically appealing; domestic waste undermine. Consequently, it is recommended that innovative approaches are pursued for domestic waste management in order to flourish and sustain the industry. Keywords: Human waste, human settlements, tourism, on-site sanitation, contamination, aesthetic value, water quality, sustainability

On-Site Sanitation and Its Effects on the Recreational Waters of Nyali-Bamburi-Shanzu and Diani-Chale –Kenya

This paper presents the effect of on-site sanitation systems on the recreational waters of Nyali-Bamburi-Shanzu and Diani-Chale tourist destinations along the Kenya Coast to establish the level of contamination in these lagoon waters frequented by tourists for swimming, diving and snorkeling. Water oozing out along the beaches near hotels or a clusters of hotels and that of lagoons in front of the beach hotels were sampled for laboratory examination to determine the levels of contamination by nutrients and micro-bacteria. Nitrites and E. coli –indicators of recent contamination by human wastes were of major interest. The sampling and analysis spanned the whole year to capture the four tourist seasons and the wet and dry periods of the year. The results of analysis established the in-effectiveness of the on-site sanitation systems in containing human waste. Topology and rock formation promoted transportation of contaminants downstream for measurable levels of nutrients and E.Coli to be detected in the lagoon waters. Nutrients and bacteria levels were higher in the lagoons in the wet periods than during dry weather. This was linked to of diffuse pollution from surface run-off, leachates from dumpsite, and discharges of contaminated water into the lagoons. Specifically for Diani-Chale, the levels of contamination were observed to be in sync with the peak tourist season, where the higher levels could be explained on account of the large number of people (tourist  plus  local people), which increased significantly as the number of local people increased to cash in on the opportunities the industry offered during this period only to decline to low contamination levels during the low-tourist season when the tourists return to their home countries and the local people move to their rural homes for farming activities. Variation of contaminant levels as a pattern due to migration of the people was not observed in the NBS study area on account the area being more urbanized, people depend on other sectors for their socio-economic activities. Overall, the contamination levels in the two study areas are generally still low. However, with increasing urbanization and investments in the tourism industry, the problem may grow to unacceptable levels and action needs to be taken to address it as an emerging problem. Keywords: Lagoon waters, on-water activities, on-site sanitation, human waste management, contamination, nutrients, micro-bacteria, E. col

Methylene Blue Adsorption onto Coconut husks/Polylactide Blended Films: Equilibrium and Kinetic Studies

The removal of cationic methylene blue (MB) from aqueous solutions by coconut husks/polylactide blended films was studied in a batch system. Experiments were modeled as a function of contact time, initial dye concentration, ionic strength, adsorbent dose, temperature and initial solution pH. Equilibrium data fitted the Langmuir isotherm model (R2>0.9866) with monolayer adsorption capacity qm = 16.34mg/g at 296K. Adsorption kinetics followed the pseudo-second model (R2>0.9997) hence chemisorption rate limiting step was dominant. The results have shown viability of coconut husks/polylactide blended films for the removal of recalcitrant MB from both domestic and industrial wastewaters. Key words: coconut husks, polylactide, methylene blue, isotherm, kinetic

HETEROSIS IN CHICKPEA FOR GRAIN PRODUCTIVITY IN EMBU COUNTY, KENYA

Chickpea is a major source of proteins especially in arid and semi-arid areas of Kenya. However, its average yield per hectare is low when compared to neighbouring countries. This research was carried out to determine the levels of hybrid vigour on yield in the F1 generation. To obtain the F1s, reciprocal crossing between Mwanza 2 and Chaina I was carried out with controls being the parental lines. The experimental layout was a randomized block design replicated thrice for three seasons. A spacing of 50x20cm was used in plants, while all other agronomic practices were maintained constant. Data on grain yield and biomass per plant was obtained by measuring the weight, then subjecting it to a one-way ANOVA in SAS 9.4 software. Mwanza 2 expressed the highest biomass (2.56g), while both parents attained a maximum grain yield of 1.69g per plant. Chaina I x Mwanza 2 hybrid expressed maximum means of F1s for biomass (2.31g) and grain yield (1.4g) per plant. Chaina I x Mwanza 2 hybrid recorded the highest biomass and grain yield in better parent heterosis with 14.36% and 330% respectively. Mid-parent heterosis means were also highest at 24.53% and 405.88% for biomass and grain yield respectively. Further, the heritability was maximum for biomass under Mwanza 2 x Chaina I, varying from 93.1% to 100%, while Chaina I x Mwanza 2, expressed maximum grain yield and harvest index. Better parent heterosis and mid-parent heterosis was highest in Chaina I x Mwanza 2 than its reciprocal, Mwanza 2 x Chaina I

Improvement of the Quality of Cotton Fabric Through Functionalization of Tagetes minuta (TaMi) Dye

Non-functionalized and functionalized Tagetes minuta (TaMi) dye obtained using methanol and water showed varied fastness onto cotton fabric. Furthermore, HPLC profile of the methanol dye showed more peaks and hence was expected to be richer in secondary metabolites that impacted on the quality of the dye. This was confirmed from the IR spectrum which showed more functional groups from this dye as compared to the water dye. The functionalized methanol dye exhibited good fastness onto cotton textile and minimal bleaching effects, as compared to non-functionalized H2O and MeOH dye. Furthermore, the process involved the use of low quantities of the dye material/solution as compared to non-functionalized dye, hence resulting to less impact on environmental degradation. The colors of the textiles produced from the methanol functionalized dye were highly resistant to fading or running. The cotton fabric articles that were tri-mordanted at 80-90 °C and dyed using the functionalized dye exhibited uniform absorption of color of the dye and good fastness. Functionalization of the methanol TaMi dye was obtained by the reaction of the TaMi dye with 1,4-butanediol diglycidyl ether (BDDE). The alum tri-mordanted textile materials produced brighter colors of brown as compared to the singly alum mordanted fabrics. This is due to the tannin factor in tri-mordants that led to the brightening effect. Furthermore, longer duration of time for tri-mordanting might have had a greater impact to the brightness effect. Additionally, characterization of the dye obtained using the two solvents was done using HPLC and IR. The formed functionalized dye has many applications as colorants in textiles, paints, inks, plastics, cosmetic articles and electronic materials. Keywords: Cotton fabric, Tagetes minuta, dye, functionalized, 1,4-butanediol diglycidyl ether, colorants DOI: 10.7176/JNSR/11-16-02 Publication date:August 31st 202

Effects of Variety, Spacing and Nitrogen Application on Chickpea (Cicer arietinum) Growth and Yield in Embu County, Kenya

Chickpea is a pulse crop that is rich in proteins and helps in fulfilling the requirement of protein for vegetarian people thus yield maximization needed. This study aimed to determine the effects of spacing, nitrogen rates, and their interactive effects on the growth and productivity of the selected chickpea varieties. Field experiments were conducted at Mwea, Kenya between 2017 and 2018 involving four varieties (Saina K, Mwanza 2, Chaina I and Chaina III) at a spacing of 50x10cm, 50x20cm, and 50x30cm, and starter nitrogen-fertilizer application rates 0kg, 30kg, 60kg, and 90kg ha-1. A split-split plot design arranged in a 4x3x4 layout was used in the current study. Data related to plant height, biomass, grain yield, and harvest index were collected and subjected to statistical analysis by GLM in SAS 9.4 computer software. Variations occurred in measured traits like the height of crops (34.81-38.00cm), biomass yield (3.31 - 8.08t ha-1), seed yield (0.14 to 1.9t ha-1), and percent harvest index (5 - 45%) was reported. Mwanza 2 expressed the highest plant height, biomass, and grain yield. The highest plant biomass was obtained under 50x10cm spacing, while the highest grain yield weight was reported under 50x30cm spacing x 60kg N ha-1. From the results of the study, it can be concluded that the highest enhanced growth and productivity of chickpea were realized at interactions of Mwanza 2x50x10cmx90kg ha-1 nitrogen rate in the study area

Reliability analysis of shear design provisions for cold formed steel sections

This study focuses on the structural reliability analysis of cold-formed steel (CFS) sections under the ultimate limit state of shear. It considers two design models: the EN 1993-1-3 standard and its recent modification proposed by a previous study. The bias and uncertainty in these models were calibrated by comparing the design models’ prediction to 67 experimental results. Reliability analyses for the CFS beams, designed according to both models, were conducted using Monte Carlo Simulation (MCS) and the First Order Reliability Method (FORM). This analysis incorporated the model uncertainty and other parameters describing these models into the stochastic description. The 10% fractile of the reliability values for beams designed using the existing EN 1993-1-3 provisions showed values that were more conservative than those of the modified EN 1993-1-3 provisions, compared to the reliability target of 3.8. A FORM sensitivity analysis identified the yield strength of steel f y b and the resistance model uncertainty Γ R as the main positive drivers of uncertainty in the computed reliability indices of the design models. Additionally, a multiplicative modification factor was proposed for both the existing and modified versions of EN 1993-1-3, ensuring that these models optimally meet the specified reliability targets of 3.8 and 4.3 for Eurocode reliability classes 2 and 3, respectively. The proposed modifications maintain the partial factor γ M 0 at 1.0, as stipulated by the EN 1993-1-3 provisions for the resistance of the cross-section