The Physico-Chemical Quality of Streams and Channels Draining into River Rwizi, South Western Uganda

Abstract

There is an increased human population along the catchment area of river Rwizi who are engaged in various activities with potential to contaminate river Rwizi especially along the streams. Studies have been done to examine the physico-chemical quality of the mainstream river Rwizi in Mbarara Municipality. However, the comprehensive source of contamination may be beyond the municipality and yet the streams have not been investigated to substantiate their contribution on quality degradation of the river and this formed the basis of the study. This study determined the physico-chemical parameters of streams draining into river Rwizi. Raw water was purposively selected from streams in the upstream, midstream and downstream sections of the river. Water samples were analyzed for 15 physico-chemical parameters including dissolved oxygen (DO), colour, turbidity, total suspended solid (TSS), total iron (Fe), phosphates (3 4 PO −), alkalinity, magnesium (Mg), calcium carbonate (CaCO 3), temperature, pH, ammonium (4 NH +), electrical conductivity (EC), chloride (Cl) and nitrates (NO 3). The water samples were analyzed following the standard methods of American Public Health Association and standard operating manual (1985). The obtained values were also compared with the international Environmental Protection Agency (EPA, 2001) guidelines for water quality and the National Environment Management Authority (NEMA, 1999) standards for waste water. The results showed that most of the streams in the downstream generally recorded the highest levels (p < 0.05) of the physico-chemical parameters followed by the midstream and lastly the upstream. Streams in the downstream recorded the highest levels in most of the parameters tested i.e. bus park stream (tempera

The Physico-Chemical Quality of Effluents of Selected Sewage Treatment Plants Draining into River Rwizi, Mbarara Municipality, Uganda

“…This may be due to concentration of calcium carbonate in the sewage effluent at higher temperatures during the dry season than during cooler temperatures of the wet season. The significant positive correlation of temperature and CaCO 3 obtained by [10] supports the fact that CaCO 3 is concentrated at higher temperatures of the dry season compared to the low temperatures of the wet season.…”

“…There was also low variability of iron (Fe) concentrations within samples of Kakoba and Taso sewage effluents (CV; 22.8% and 38.02% respectively) ( Table 1) However, the sewage treatment processes usually remove heavy metals including Fe [33]. The significantly higher concentration of iron during June-August than March-May period in sewage effluents in Kakoba can also be attributed to concentration of Fe at slightly higher temperature during the relatively dry season [10].…”

“…Physiochemical analyses of sewage effluents were performed using standard methods for American Public Health Association and standard operating manual [2]. The full procedures of analysis of each of the physico-chemical parameters (dissolved oxygen, colour, turbidity, total suspended solid, total iron, phosphates, alkalinity, magnesium, calcium carbonate, temperature, pH, ammonium, electrical conductivity, chloride and nitrates) are detailed in the study by [10].…”

“…Temperature is a key factor in biological activity and microorganisms can be psychrophilic, mesophilic and thermophilic [11]. Aquatic organisms thrive only within specific temperature ranges [10]. Table 1.…”

“…On the other hand, there was no significant variation of Fe during the June-August and March-May sampling period in sewage effluents in Journal of Water Resource and Protection Taso (t = 1.589, p = 0.187). Iron displayed low values in the sewage effluents possibly because of the effective removal of iron during the treatment process despite the fact that[10] reported significantly high amounts of Fe downstream of river Rwizi where Mbarara municipality is situated and they attributed this to the urbanized and industrialized area of the municipality. The identified potential sources of iron in the municipality by the same authors included staining from laundries, plumbing and welding, milk and food industries and water treatment plants where cast iron, steel, and galvanized iron pipes are used in water distribution.…”