This study evaluated the microbiological effects of hospital wastewater discharged into the soil environment using standard microbiological procedures. The highest total bacterial count (8.3±0.5×1010 cfu/ml) of the wastewater samples was observed in the collation point sample while the laundry wastewater sample had the least number of 5.4±0.5×107 cfu/ml. The collation point wastewater sample had the highest total coliform count (4.1±0.1×108 cfu/ml)while the laundry wastewater sample produced the least count of 2.3±0.1×101 cfu/ml. The highest total coliform faecal count of 4.2±0.3×105 cfu/ml was observed in the collation point wastewater sample while the least count of 2.4±1.2×103 cfu/ml was seen in the laundry wastewater sample. The mortuary wastewater had the highest total fungal count of 3.1±0.2×105 cfu/ml while the least count was seen in the collation point wastewater 2.9±0.2×102 cfu/ml. The total viable numbers of the soil samples ranged from 5.0±0.0×108 cfu/g (200m away from the point of discharge) to 8.4±1.6×1012 cfu/g (point of release) while the total coliform counts ranged from 2.3±0.0×104 cfu/g (200m away from the point of discharge) to 3.9±0.8×108 cfu/g (point of discharge). The highest total faecal count of 3.7±0.5×104 cfu/g was observed in the sample from the point of discharge while the least count was seen in the sample collected 200m away from point of discharge 2.3±0.1×102 cfu/g. Total fungal count ranged from 2.4±0.5×107 cfu/g (200m away from the point of discharge) to 3.4±0.5×108 cfu/g (point of discharge). The bacterial species isolated were Escherichia coli, Erwinia, Serratia, Enterococcus, Staphylococcus, Streptococcus, and Salmonella. Others were Pseudomonas aeruginosa, Proteus, Neisseria, Actinomycetes, Shigella, Bacillus and Enterobacter species. The fungi isolated include Aspergillus niger, Aspergillus fumigatus, Trichophyton rubrum, Candida, Penicillium and Rhizopus species. Bacillus spp., Staphylococcus epidermidis, Penicillium spp. and Rhizopus species were the most frequently distributed (100%), followed by S. species, Enterococcus spp., E. coli, Pseudomonas aeruginosa, Proteus spp. and Candida spp. (80%). Salmonella spp., Shigella spp., Enterobacter spp. and Trichophyton rubrum had the same rate of 60%, respectively while the least occurrence was seen in Streptococcus spp., Neisseria spp., Actinomyces spp. and Aspergillus niger with the rate of 40%, respectively. The high microbial loads of the isolates and the high densities of the coliforms indicate there is, therefore, contamination of the soil environment as a result of the discharged hospital wastewater, which could probably be hazardous to human health.

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AIM This study aimed to simulate deactivation of E. coli in soils amended with cattle manure after burning, anaerobic digestion, composting or without treatment. METHOD AND RESULTS The Weibull survival function was used to describe deactivation of E. coli. Parameters for each treatment were determined using E. coli measurements from manure-amended soils and evaluated against measurements at different application rates. A statistically significant correlation and high coincidence between the simulated and measured values was obtained. The simulations revealed that although anaerobic digestion or burning of cattle manure effectively reduced the E. coli loads to background levels, burning retained very little nitrogen, so the ash residue was ineffective as an organic fertiliser. Anaerobic digestion was most effective at reducing E. coli levels while retaining a high proportion of N in the bioslurry residue, but the persistence of E. coli was higher than in compost. CONCLUSION The results from this study suggest that the safest method for production of organic fertiliser would involve anaerobic digestion to reduce E. coli followed by composting to reduce its persistence.

This research was carried out to investigate effect of ethylenediaminetetraacetic acid and ammonium oxalate on the prevalence of microorganisms and removal of aluminum in soil by bitter leaf plant (Vernonia amygdalina). The test plant was sown in aluminium-polluted soil (conc. ═ 150mg Al kg -1 soil). One gram of each chelating agent was dissolved in 1.5 litres of water and applied at different time intervals; application on a day prior to sowing of test plant in metal-polluted soil, application on the day of planting, application at one week after planting; at one month after planting. For the control soils, chelating agent were not added, although aluminium-contaminated. In the control, aluminium concentrations in leaf tissues were 16.20mg/kg compared to a staggering 9.20mg/kg in EW1 and 5.24mg/kg in OD1. However, heavy metal concentration of the leaves of Vernonia amygdalina in the control, EW1, EM1, OD-1 and OW1 were significantly similar (P>0.05). Concentration of aluminium in the stem tissues were also similar in ED1, EM1, OD-1, OD1 and OW1 (P>0.05) were concentration ranged from 5.42mg/kg to 7.98mg/kg. Compared to the control, aluminium concentration in stem tissues was 4.95mg/kg comparable with 3.42mg/kg in OM1. In the plant root, OD1 had the highest accumulation of aluminium in the root (16.92mg/kg); however concentrations of aluminium in the roots were also statically similar in OW1 (15.08mg/kg), OM1 (13.84mg/kg), OD-1 (14.72mg/kg), EM1 (15.12mg/kg) and in the control (13.52mg/kg). Results of the following also showed concentrations of residual aluminium in the soil ranging from 68.25mg/kg in the control to 109.85mg/kg in ED1 soil. After three months of planting, results show that the total bacteria count for ED1 (5.3 × 10 4 cfu/g) had the highest while OM1 (3.9 × 10 3 cfu/g) had the lowest. For fungi isolates, the highest was control (8.2 × 10 3 cfu/g) whereas the lowest were OD-1 (6.8 × 10 2 cfu/g). The most prevalent microorganisms in the spiked soil with heavy metal are Bacillus subtilis represented in all the samples for bacteria while Aspergillus niger representing fungi. The perseverance of the test plant in the aluminium spiked soil is an indication of adaptation to the stress imposed by the concentration of aluminium in soil. In spite of the metal composition within the soil, it was observed that a number of microorganisms existed. This may therefore suggest a favourable environment for the microorganisms within the soil rhizospheric region of Vernonia amygdalina. © JASEM https://dx.doi.org/10.4314/jasem.v21i4.4

<p>Organic wastes, such as cattle manure, are widely used as organic amendments but may constitute a potential risk to human and animal health if they are not properly treated before application to agricultural soil. This study investigated the impact of different common household treatment methods on the reduction of pathogens in organic wastes and the spread of pathogens to food crops. Fresh cattle manure was subjected to three different treatments available to households; anaerobic digestion, burning and composting. Sub-samples were screened for E. coli contents using standard plating and IDEXX Colilert Quanti-Tray 2000 system. The numbers of organisms were used to assess the effectiveness of the treatment methods in the reduction of pathogens in the organic wastes. The E. coli count of the cattle manure was 391.42 CFU/g before treatment. After treatment, there was significant reduction in the E. coli in all treatments. Burning was most effective at reducing pathogens in the cattle manure (95%) followed by anaerobic digestion (50%) and composting (40%). Ash, bioslurry, compost and untreated manure were all significantly different in the ratio of pathogens to nitrogen. Bioslurry contained more nitrogen than ash, compost and untreated manure. Application of the recommended nitrogen dose of 120 kg/ha as bioslurry resulted in significantly lower contamination of soil (4.19 most probable number (MPN) per g) than ash (9.73 MPN/g), compost (6.89 MPN/g) or untreated manure (13.77 MPN/g). The E. coli content of lettuce grown on soil amended with ash, bioslurry or compost at recommended rates was significantly lower than lettuce crop grown on soil amended with untreated cattle manure. The results from this study provide information on the transmission of the pathogens remaining in the treated and untreated wastes when applied as organic fertilizer to food crops. This information will help to reduce the potential risks associated with the use of organic manures in growing food crops, as well as determining the optimum rate of application of organic waste after treatment.</p>