Biosorption of Selected Heavy Metals Using Green Algae, Spirogyra Species

Biosorption studies were conducted to determine the adsorption parameters (pH, contact time and adsorption capacity) of cadmium, chromium, copper and lead in model aqueous solutions using green algae, spirogyra species. pH was optimized for each heavy metal. The optimum pH values were found to be 5.5, 5.8, 5.9 and 5.0 for cadmium, chromium, copper and lead, respectively. The adsorption process was second order and fitted the Langmuir isotherm better than the Freundlich. Adsorption capacities were found to be 22.52, 38.19, 35.59 and 94.34 mg/g for cadmium, chromium, copper and lead, respectively. The biosorption process was rapid with contact times of 15 minutes for cadmium, 40 minutes for chromium and copper and 50 minutes for lead. The optimum initial concentrations for metal adsorption ranged from 500 - 700 µg/mL. Adsorption kinetics of the metals on green algae were also investigated. The experimental data was tested for biosorption kinetics using first and second order kinetic models and was found to follow second order kinetics. The concentration of the selected metals was determined in algae and in the parent water. The results in both samples by ICP – OES were 1.81 ± 0.11, 64.33 ± 0.35, 17.14 ± 0.155 and 12.08 ± 1.80 µg/L in water and 2.30 ± 0.09, 12.17 ± 0.20, 25.61 ± 0.74 and 60.50 ± 1.57 µg/g for cadmium, chromium, copper and lead in algae, respectively. The average concentration factors were Cd (2547.01), Cr (367.02), Cu (1843.59) and Pb (7154.95). Little correlation was found between the heavy metal concentration in parent water and in algae from the same water (R ≤ 0.32). The concentration of the acid-leached metal fraction from the algal surface, correlated well with the total metal taken up by the algae, (0.55 ≤ R ≤ 0.94). This work demonstrates the potential of green algae as both a biosorbent and bioindicator of water pollution by the selected heavy metal

Determination of Some Selected Heavy Metals in Fish and Water Samples from a Section of Migori River

Samples of Tilapia (Oreochromis niloticus) and African catfish (Clarias gariepinus) were collected from a section of Migori River. The moisture content of freeze-dried body of the fish collected from four sites ranged between 62.6% and 86.6% (m/m). An optimal procedure required 12 mL mixture of HNO3, HClO4, and H2O2 (3:2:1, respectively) to mineralize powdered samples in open refluxed digestion vessels: 0.5 g of the fish body. The concentrations of 3 toxic elements Cd, Pb and Hg) in the body of the fish was determined by atomic absorption spectrophotometer. The concentrations varied, respectively; Cd = 0.4 - 1.85, Pb = 0.05 - 0.5 and Hg = 0.07 - 0.096 in mg of element/kg of fish. The concentration of those three heavy metals in water samples was also determined similarly and varied, respectively, as (mg of element/L of water sample); Cd = 0.06 - 0.66, Pb = 0.28 - 0.36 and Hg = 0.5 - 0.74. Application of the statistical t-test on heavy metal elements data has shown that there was a significant difference between the mean concentrations of Hg in water samples. There is no significant difference between fish as well as water sample from the river. Keywords: Tilapia Fish, African Cat Fish, Clarias Gariepinus, Oreochromis Niloticus, Toxic Metals, Water Pollution, Migori river

Effects of Seasonal Variation on Performance of Conventional Wastewater Treatment System

The study was to determine the seasonal differences of conventional wastewater treatment process. This was done by sampling and analyses of wastewater samples from four different points during the dry and wet seasons of the year 2019. Water samples were taken from influent point, primary effluent, trickling filter effluent and final effluent. Gravimetric method was used in determining Total Suspended Solids (TSS) and Total Dissolved Solids (TDS). The BOD5 technique was used for determination of Biological Oxygen Demand (BOD) and the digestion method was used for determination Chemical Oxygen Demand (COD). Temperature, pH and conductivity were measured using respective meters. Analysis of Variance showed that there was significant difference (p < 0.05) in all the parameters quantified at all the points of treatment during the two seasons. The results showed that BOD and COD both reduced from one point to the next during the two seasons of study. The TSS levels increased after primary pond effluent undergoing treatment at the trickling filter and the temperature also increased after the trickling filter effluent undergoing treatment at oxidation ponds. The levels of conductivity and TDS decreased from one treatment stage to the next during dry season but during the wet season the levels of these parameters increased from one stage to the next except that the levels reduced after the primary pond effluent underwent treatment at the trickling filter. The various stages of wastewater treatment plant under were effective during the two seasons however, wet season recorded lower figures for most of the parameters. Keywords: effluent, influent, wastewater, seasonal variation, ponds DOI: 10.7176/JEES/11-7-06 Publication date:July 31st 202

Heavy Metals in Edible Vegetables Grown Around Sewage Ponds and Damp Site in Eldoret Town, Kenya

Exposure to heavy metals including Ni, Cd, Cr, Co, Pb, As, Hg, Zn and Cu, has been recognized as a risk to human health through the consumption of vegetables. This study investigates the source and magnitude of heavy metal contamination in various kinds of vegetables including kales, spinach, carrot, cabbage and tomato in Eldoret town. In the study the concentrations of Pb, Cd, Ni, Mn, Co, Cu, Fe and Zn in vegetable crops around the municipal damp site and near the sewage ponds were investigated; and their contamination status with respect to international food standard guidelines evaluated. The lead in vegetables in all tested areas had higher level than that of the permissible limits of international standards. Except lead, it is concluded that nearly all the samples did not exceed the Intentional Food Standards maximum level (ML) in vegetables in Eldoret. Contaminated soil and vegetables may contribute to a progressive gathering of these metals in food chain that might affect ecosystem with possible noxious effect on human health. The study shows that vegetables growing soil containing higher amount of metals could be transferred into edible parts of the plant, so study area should be monitored regularly to avoid health risk of human being due to exposure of toxic level

Physicochemical and Microbiological Quality of Roof-harvested Rainwater in Urban Areas: A Review

This work proposes to consider the quality of roof-collected rainwater. There are three main stages. In the first stage, rainfall washes out the urban atmosphere with contaminants from aerosols and gases. The second stage refers to the catchment, where there is contamination due to the wash-off of particles settled on the roof’s surface roofing materials. The third stage refers to the first-flush, storage and plumbing system. In each stage, different processes take place and add specific contaminants to the initial precipitation. Only in the third stage, after the discard of the high-polluted initial rainwater, some physical processes (for example sedimentation and correction of pH) can also improve the quality of the rainwater harvest. This approach offers a clear view of the overall contamination processes that take place in a rainwater harvesting system.The most common microbiological and physicochemical contaminants that can be found in rainwater harvesting system were considered, together with the eventual presence of waterborne pathogens and emerging chemical contaminants, according to an extensive review of previous scientific works. Keywords: Rainwater, Physicochemical, Microbiological, Contaminants, waterborne DOI: 10.7176/JEES/12-10-05 Publication date:October 31st 202

Assessment of the Impact of Anthropogenic Activities on the Drinking Water Qualities of Boreholes/Shallows Well Water in Huruma Estate -Eldoret, Kenya

The objective of this research was to investigate the drinking water qualities of boreholes/shallows well water used by inhabitants of Huruma –Eldoret , by comparing the chemical, physical and bacteriological qualities with WHO standards. Samples were collected in the dry season in the months of January and February, 2014 and analysed for pH, Turbidity, TDS, Conductivity, Total Hardness, Chloride, Nitrate, Phosphate, Calcium, Magnesium, Lead, Zinc, Total Iron, Copper, Manganese, Cadmium, Total Chromium, Total Coliform, Feacal Coliform and E-coli. Standard methods were adopted for field and laboratory studies. Results of the comparisons from the four sampled stations showed that the water was not acidic as the pH was within acceptable limits. The turbidity level was high in three of the sampled stations with the highest in Lutheran church (55.0 NTU). The metals were within the safe limits. The heavy metals investigated were within tolerable limits of WHO standards with the exception of lead and total iron. Lead and total iron were detected in all the sampled stations butexceeded tolerable limits in Bondeni and Lutheran church. The Total coliform exceeded the tolerable limits for drinking water. However the hardness levels were within tolerable limits. These results showed that the borehole/well water from Huruma estate is contaminated with some pollutants entering the water table. The borehole water should therefore be protected and treated before consumption. There is need for periodic monitoring of water samples from boreholes/wells sources to ascertain their qualities

Health Effects of Pesticide Exposure among Formulators, Repackers and Store Workers in Nairobi, Kenya

Though it is widely believed that adverse health effects occur among farm workers who handle pesticides, few studies have been done to quantify the extent to which pesticide formulators, re-packers and store workers are affected. The present study assessed the prevalence of signs and symptoms of illness due to pesticide exposure among factory workers in Nairobi Kenya using a descriptive cross- sectional study design on consenting factory workers. A questionnaire was administered enquiring about their biodata, work practices and occurrence of signs and symptoms associated with pesticide poisoning. Data was coded, entered into MS Access database and analyzed using SPSS version 11.5. Test for significance was done using chi-square to identify key variables associated with pesticide poisoning. Workers who had been in employment for less than one year reported a higher prevalence of signs and symptoms associated to pesticide poisoning such as burning skin (P = 0.004) and dizziness (P = 0.006). Workers who handled organochlorine pesticide had higher prevalence of burning of skin (P = 0.002), convulsions (P = 0.003), twitching (P = 0.004), painful swallowing (P = 0.004), dermatitis (P = 0.019) and headache (P = 0.028) among other pesticide exposure related symptoms. Workers who had handled pesticides for a longer period of time appeared to have less signs and symptoms of pesticide poisoning probably suggesting that long term exposure to pesticides either imparted some form of acquired immunity to pesticides or that their longer experience resulted in better risk perception and management. Keywords: pesticide, organochlorine, organophospate, formulator, poisoning