ABSTRACT. The levels of total phosphate in selected surface water and groundwater bodies from Manzini and Lubombo regions of Swaziland were determined using UV spectroscopic method. Samples were collected from three rivers (upstream and downstream of each), three industrial effluents, one reservoir, one pond, one tap water and fifteen boreholes. Mean phosphate levels in the tap water and reservoir varied between 0.08-0.09 mg/L while for the river samples, the range was 0.11-0.37 and for the industrial discharge, it was 0.11-1.60 mg/L PO4-P. For the ground water systems it ranged between 0.10-0.49 mg/L PO4-P. The mean phosphate levels in all the analyzed surface and groundwater samples were below the recommended maximum contaminant level (MCL) by SWSC (Swaziland Water Service Corporation) -i.e. 1.0 mg/L for drinking water; 2.0 mg/L for rivers and industrial effluents, and the South African criterion of 1.0 mg/L PO4-P, for sewage effluents being discharged into receiving waters. However, pooled mean values for all the sites were higher than the USEPA criterion of 0.03 mg/L maximum for uncontaminated lakes. Dominant factors considered to have influenced the levels of phosphates in both the surface and groundwater samples analyzed include industrial activities (where present), agricultural activities (including livestock), population density, location (urban, suburban or rural), soil/rock type in the vicinity of the sampling point, climate and rainfall pattern of the area or region concerned.

Speciation analysis of heavy metals in sewage sludge provides a better understanding of the extent of mobility and bioavailability of the different metal fractions and helps in more informed decision making on application of sludge for agricultural purposes. Assessment of bioavailability of metals based on regulations expressed in terms of total metals alone may be conservative and restrictive from the point of view of the use of sludge for agricultural applications. Total metals may also be poor indicators of uptake by plants. Sewage sludge samples generated from seven wastewater treatment plants in Swaziland were analyzed for the four fractions of metals species, namely, exchangeable, reducible, oxidizable and residual fractions. The experimental results indicated that arsenic was predominantly associated with the residual matrix. Chromium was dominantly found in the residual fraction followed by oxidizable fraction. Lead and copper were predominantly associated with oxidizable fraction (bound to organic matter). For more polluted effluents such as Matsapha waste water treatment plant, some metals such as nickel were also found significantly in the mobile fraction. By contrast zinc and to a certain extent nickel were present in significant proportions in the more mobile (exchangeable) fraction. The experimental result indicated that the percentage immobility ranges from 10% to 70% with respect to the residual solid fraction of the metals which should be considered as an additional safety factor in the assessment of the suitability of the sludge for agricultural uses with respect to heavy metals.

Acid mine drainage (AMD) is an industrial pollution of prime concern for the whole world. It is the driving force for an array of water pollutants especially heavy metals. Heavy metals (Cr, Mn, Fe, Ni, Co, Cu, Zn, Pb, Cd) were investigated in this study. Water and sediment samples were collected from the Ngwenya Iron Ore Mine Quarry Dam to investigate the occurrence of AMD phenomenon in the old mine. The main Fe compounds found in the Ngwenya Mine ore are haematite and pyrite. The Quarry Dam is located in one of the mine pits and it has neither visible inlet nor outlet. Physico-chemical parameters (pH, EC, ORP, T) were determined in the water by Electrochemical methods using the WTW 340i probes. Anions in the water were quantified by Ion Chromatography (IC) whereas heavy metals in water and sediments were quantified by Flame Atomic Absorption Spectrometry (FAAS). The BCR-Sequential Extraction procedure was used to speciate the heavy metals in the sediment samples. The mean pH of 4.34 in the Quarry Dam water is comparable to the pH of other AMD polluted water. The high mean EC of 4.522 mS/cm depicted that the water was laden with ions which are dissolved from the ore by the AMD. The sulfate ion, a well-known indicator for AMD pollution in water, is the second dominant anion where the order isThe heavy metal levels in water and sediments were in the order Co > Ni > Cr >Zn > Mn > Cu > Fe > Cd > Pb and Fe > Mn > Cr > Ni > Pb > Co > Cd > Cu > Zn respectively. The heavy metals are all bioavailable, hence they are potential health risks to both biota and residents in the vicinity of the mine. The pH of the water in the Quarry dam is comparable to those obtained for some other AMD polluted water. It is inferred that AMD is being produced in the old mine. It is recommended that an Environmental Impact Assessment of AMD must be carried out before the mine is re-opened.

The feasibility of household level treatment of grey water with activated charcoal was performed using laboratory batch adsorption testing on locally available charcoal media. The study results indicated that the potential for removal of organic matter was significantly high for the high pH cloth wash water compared to the low pH kitchen wastewater which also contained non-adsorbed organics. The addition of ash considerably improved the removal and projected life length of adsorption media for kitchen wastewater treatment. The adsorption isotherms obtained were all modeled adequately using the Freundlich isotherm while the isotherm shapes display different types of adsorption for the different streams of grey water because of the heterogeneous nature of the adsorbates in grey water. The replacement life length of activated charcoal for single drum household level treatment ranged between 7 and 15 months. For family daily flow rates up to 400 lit/day, the replacement costs of a single drum charcoal per cubic meter of grey water treated were calculated to be below the current tariff levels for acquiring water in cities in Swaziland. A considerable part of the grey water pollutant can be removed through pretreatment by sorption alone such as by filtration through sand or other cheap media before adsorption. For complete household level treatment of grey water, a three-step treatment consisting of sand pre-filtration, activated charcoal adsorption and sand post-filtration are recommended.

Twenty-three water samples and three "yellow boy" samples were obtained from different water bodies located at the foot of the Ngwenya Mountain on top of which the old Ngwenya Iron Ore Mine is located. The samples were analysed for pH, electrical conductivity (EC), redox potential (ORP) and temperature (T). The dominant Fe species was determined using a UV-VIS spectrophotometer. Selected anions namely: halogens (F − , Br − , Cl −), the nutrients (2 NO − , 3 NO − , 4 PO 3−) and the best indicator for AMD pollution (4 SO 2−) were analysed using Ion Chromatography (IC) while the selected heavy metals, namely: Cr, Mn, Fe, Ni, Co, Cu, Zn, Pb and Cd were analysed using Flame Atomic Absorption Spectrometry (FAAS). The physico-chemical parameters ranges obtained were pH (6.32-8.63), EC (11.00-585.33 µS/cm), ORP (−93.67-79.33 mV) and T (7.60˚C-18.57˚C). The levels of the Fe species (ppm) in the water samples were Fe 2+ (0.56-3.17) and Fe 3+ (0.00-0.73). Measured mean anion ranges in ppm were F-(0.00-0.15), Cl − (1.5-11.19), 3 NO − (0-13.25) and 4 SO 2− (0.05-22.29). The mean ranges for the heavy metals in the water samples in mg/l were Cr (0.00-2.46), Mn (0.00-0.30), Fe (0.00-0.34), Ni (0.00-0.34), Co (0.00-0.29), Cu (0.00-0.07), and Cd ((0.01-0.11) whilst Zn and Pb were not detectible. The average pH in all the sites was within the acceptable range (6.5-8.5) according to WHO standards except for two sites. Fe 2+ was the dominant Fe species in the water samples. The water was free from anion pollution because all measured anion levels were below the guideline by WHO. The relative percentages of sites polluted by the respective heavy metals were: Cd (83%), Cr (71%), Ni (46%), Co (42%), Mn (17%), Fe (4%) while no site was polluted by Cu, Zn and Pb. The State needs to set up sound remediation strategies to save the populations around the Ngwenya Mine from the heavy metal pollution they are exposed to by using water polluted by the mining activities.