Many science-based institutions in most developing countries use heavy metal containing salts in practical teaching sessions. The commonly used chemicals are the salts of lead (II) and copper (II) and the wastes generated end up into the environment when untreated. Thus, a study was done to remove lead (II) and copper (II) ions from mono synthetic aqueous solution using bio-char from Ficus natalensis fruits (FNF). This was done at varied pH, contact time, temperature, bio-char dosage level, salinity and metal ion concentration using the batch approach. The residual metal concentrations were determined using the atomic absorption spectrophotometer. The optimum pH for the adsorption of copper (II) and lead (II) ions was found to be 4.0 and 5.0 respectively. The maximum percentage adsorption of copper (II) and lead (II) by the FNF bio-char was established at 60 minutes contact time, 47.5˚C and 0.4 g adsorbent dose. Increase in the metal ion concentration and the presence of interfering ions in the aqueous solution lead to decrease in the percentage adsorption. The highest adsorption capacity was found to be 161.29 mg/g and 1250 mg/g for copper (II) and lead (II) ions respectively. The thermodynamic parameters indicated the feasibility of the adsorption of copper (II) and lead (II) on the bio-char of FNF. Thus, bio-char from FNF may be used as an adsorbent in waste management where copper (II) and lead (II) ions are present at a concentration range of between 5 and 100 mg/l.

In the current study, water from Chuho springs used as the main water source in Kisoro municipality, Uganda were assessed for their suitability as drinking water. The temperature, turbidity, conductivity, total dissolved solids, dissolved oxygen, biological oxygen demand, total hardness, total alkalinity, calcium, magnesium, phosphates, iron, copper, arsenic, chlorides and the fluoride content of the water samples were determined. Not all the parameters met World Health Organizations’ guidelines for drinking water. Temperature, dissolved oxygen and fluorides were outside the recommended limits of 15 ℃, 10-12 mg/L and 1.5 mg/L, respectively. Further studies should assess the microbiological and sanitary profile of the springs.

The potential of the Senegal date palm (Phoenix reclinata) seed bio-char to remove chromium (VI) ions from aqueous solutions by adsorption was investigated. Adsorption experiments were performed on the tannery effluent and standard aqueous solutions of chromium (VI) for varying adsorbent doses, contact times, pH, temperatures, and interfering anionic ions by batch mode. Phoenix reclinata seeds (PRS) bio-char was used in the investigation and the residual chromium (VI) was determined using the atomic absorption spectrophotometer (AAS). Results showed that the bio-char removed up to 86% of chromium (VI) ions in the effluent at pH 2. The highest percentage adsorption registered was 97% in an aqueous solution of chromium (VI) at pH 1 and this dropped to less than 10% at pH greater than 2. A general increase in adsorption with the increase in temperature was observed but reduced when the temperature was raised beyond 60˚C. The presence of interfering anions caused a reduction in the adsorption of chromium (VI) ions. The adsorption process fitted both Langmuir and Freundlich adsorption models and the maximum adsorption capacity, Q o , was 0.6593 mg/g. Thus, PRS bio-char can therefore be used by industries and institutions like secondary schools to treat effluents that contain chromium (VI).