Quantitative microbial risk assessment (QMRA) is frequently used to estimate health risks associated with wastewater irrigation and requires pathogen concentration estimates as inputs. However, human pathogens, such as viruses, are rarely quantified in water samples, and simple relationships between fecal indicator bacteria and pathogen concentrations are used instead. To provide data that can be used to refine QMRA models of wastewater-fed agriculture in Accra, stream, drain, and waste stabilization pond waters used for irrigation were sampled and analyzed for concentrations of fecal indicator microorganisms (human-specific Bacteroidales, Escherichia coli, enterococci, thermotolerant coliform, and somatic and F+ coliphages) and two human viruses (adenovirus and norovirus genogroup II). E. coli concentrations in all samples exceeded limits suggested by the World Health Organization, and human-specific Bacteroidales was found in all but one sample, suggesting human fecal contamination. Human viruses were detected in 16 out of 20 samples, were quantified in 12, and contained 2-3 orders of magnitude more norovirus than predicted by norovirus to E. coli concentration ratios assumed in recent publications employing indicator-based QMRA. As wastewater irrigation can be beneficial for farmers and municipalities, these results should not discourage water reuse in agriculture, but provide motivation and targets for wastewater treatment before use on farms.

The 26 communities surrounding the rim of the largest Crater Lake in Africa, the Lake Bosomtwe, depend on the lake for livelihood support. Water sources such as lake, streams and boreholes used as drinking water sources were collected quarterly for a period of 2 years. These were analysed bacteriologically for the determination of total and faecal coliform, Escherichia coli, Aeromonas sp., Enterococcus sp., Salmonella sp., Pseudomonas sp. and total heterotrophic bacteria (THB) using membrane filtration and pour plate techniques. The seasonal variations of these bacteria in the water sources were determined. The results showed variation of bacteria counts in all the water sources. The highest E. coli counts of 2.9 × 10 3 cfu/100 ml were recorded in the lake and the least in the borehole 2.1 × 10 1 cfu/100 ml. The difference between the total coliform, faecal coliform and E. coli counts and the water sources was significant (p < 0.05). All the bacteria count with the exception of THB, in the different water sources, had higher bacteria counts during the dry season than the wet season which are statistically significant (p < 0.05). The bacteria contamination of these water sources renders them bacteriologically not suitable for drinking purposes; therefore, drinking these waters without any form of treatments could pose health risk to consumers. These water sources can, however, be used for domestic purposes.

The study was carried out to determine the bacteriological safety of water in hand-dug wells in the Atebubu-Amantin District of the Brong-Ahafo Region in Ghana. A total of 60 samples were collected from ten hand dug wells and analysed for total coliform (TC), faecal coliform (FC), E. coli (EC), Salmonella spp. (SP) and Enterococcus spp. (ES). Data was collected in both the rainy and the dry seasons. The results obtained showed that water from all the wells in the study area did not meet the World Health Organisation guideline and Ghana standard for drinking water of zero (0) coliform forming unit (cfu) per 100 ml for TC, FC, EC, SP and ES, respectively. Contamination was found to be high in the wells during the wet season as compared to the dry season. Wells (A1 to A5) which were close to septic tanks had high bacteria counts in both seasons. The total coliform counts ranged from 2.98 to 5.93 log cfu/100 ml in the wet season and 3.10-5.03 log cfu/100 ml in the dry season. There was drastic reduction of faecal coliform count from a range of 2.78-4.55 log cfu/100 ml in the wet season to 1.70-3.51 log cfu/100 ml in the dry season. The high bacteria count in wells A1 to A5 could be attributed to the closeness of the wells to the septic tank, and contaminant transport through the saturated underground zones. It is recommended that the water should be treated properly before drinking.

The quality of irrigation water from different sources used by urban farmers in the Accra Metropolis was investigated. These were, tap water stored in dugout, surface water (from stream) and wastewater in drains. The samples were analysed for their bacteriological, physical and chemical qualities using standard methods. Analytical Profile Index (API) identification system was used to characterize and identify the bacterial species isolated in the samples. The results showed that heavy metal concentrations in the samples were within the FAO/WHO recommended limits for irrigation. The concentrations of highly toxic Lead and Cadmium were even below detection limit. Total and faecal coliform bacteria loads in all three potential irrigation water sources were above the WHO recommended limit for irrigation. Different bacteria species belonging to seven genera were identified in the three irrigation water sources. These included Citrobacter, Chryseomonas, Enterobacter, Klebseila, Proteus, Providencia, Pseudomonas. Generally, the most dominant bacterial species were Pseudomonas aeruginosa and Chryseomonas luteola. Some of these bacteria spp. can pose a health threat to farmers especially those who have challenges with their health and immune system. For example, infection with some of the bacteria species such as Pseudomonas aeruginosa in patients with cystic fibrosis is known to be deadly over periods of time

A B S T R A C TThe relationship between sunlight effect, algal biomass and faecal coliform inactivation in wastewater pond treatment systems is still not clearly understood. Increased pH and dissolved oxygen concentration in treatment ponds results in an increased destruction of faecal coliforms. Increased algal growth however results in a decreased destruction of faecal coliforms due to light attenuation. Algae also releases variable amounts and types of organic matter at various rates and quantities depending on environmental conditions and this can either aid or retard faecal bacteria destruction. We investigated the effect of algal density on faecal coliform destruction under field conditions in sunlight and darkness and how this can be affected by light intensity. In darkness, increased inactivation of faecal coliform occurred with increasing algal density. Rates of decay of faecal coliforms were much faster in sunlight than in darkness even in the absence of algae. In sunlight, rates of decay of faecal coliforms increased with increasing algal density up to a chlorophyll-a concentration of 1.3 ± 0.1 mg/L after which rates of decay decreased. Increased decay rates of faecal coliforms occurred with increasing light intensity or light input. With decreased light input of 20% of 213 W/m 2 , the optimum algal density for maximum faecal coliform decay decreased to a value which is 6-7 times the value of that under normal insolation of 213 W/m 2 . It is recommended that in future studies relating to the assessment of performance and estimation of rate of Escherichia coli or faecal coliform inactivation, one of the parameters that need to be reported as well is the insolation.