Effect of Charcoal Earth Kilns Construction and Firing on Soil Chemical Characteristics

Assessments of localized ecological and environmental impacts of charcoal production including effects on soils at kiln sites is seldom undertaken, with more emphasis being placed on the global effects of the practice such as forest degradation and deforestation. A study was undertaken in Narok, Eldoret, Moiben, and Turbo in Kenya on known charcoaling sites to investigate the impact of charcoal production on the soil chemical characteristics. Composite soil samples from 12 sampling points for all study sites were taken randomly at a depth of 0–15 cm. The samples were conditioned and analyzed for pH, particle size, Cation Exchange Capacity (CEC), extractable phosphorus, organic carbon, nitrogen, and exchangeable bases. A comparison of the soil properties between undisturbed sites and charcoaling sites showed significant differences for all chemical properties except CEC, Mg, and K. For the Moiben site, only the pH showed no significant difference (p < 0.05).  The observed high carbon content reduced with time for the one year following charcoaling activity and was attributed to soil erosion since charcoal production activities reduced the sites vegetation cover. Most chemical changes positively enhanced the nutrients content and availability, but were short lived probably due to soil erosion.  These results demonstrate the need to adopt technologies with minimum impact on the soil, or a shift to centralized production sites outside forest ecosystems or farmlands.

Distribution of Potentially toxic elements in Water, Sediment and Soils in the Riparian Zones around a Kraft Pulp and Paper Mill in Western Kenya

This chapter discusses the impact of effluent discharge on the distribution of potentially toxic elements (Pb, Cd, Cu and Zn) in water, sediments and soils near a Kraft mill in Western Kenya. Potentially Toxic Elements (PTEs) concentrations were determined at three sites: Water Intake Point, Effluent Discharge Point and Downstream Point. The mill liquid effluent parameters and gaseous emissions were also characterized. One-way ANOVA was used to analyze the spatial differences in PTEs concentrations. Principal component analysis determined the correlations between the proximity to the Kraft mill and the PTEs in soils, water and sediments. In riverine soils, Cd was 0.78 ± 0.01 mg/kg, while Pb was 94.38 ± 9.65 mg/kg. In sediments, the concentration was 16.81 ± 2.46 mg/kg for Zn, 6.16 ± 0.72 mg/kg for Cd and 75.28 ± 5.97 mg/kg for Pb. In water, Zn was 0.26 ± 0.038 mg/L, Cu was 0.75 ± 0.11 mg/L, Cd was 0.05 ± 0.004 mg/L and Pb was 1.26 ± 9.65 mg/L. The spatial distributions of PTEs in soils near the factory and across the river may have resulted from the factory’s effluent discharge and gaseous emissions. These findings should help formulate more stringent industrial effluent management programs in Western Kenya

Effect of Charcoal Earth Kilns Construction and Firing on Soil Chemical Characteristics

Assessments of localized ecological and environmental impacts of charcoal production including effects on soils at kiln sites is seldom undertaken, with more emphasis being placed on the global effects of the practice such as forest degradation and deforestation. A study was undertaken in Narok, Eldoret, Moiben, and Turbo in Kenya on known charcoaling sites to investigate the impact of charcoal production on the soil chemical characteristics. Composite soil samples from 12 sampling points for all study sites were taken randomly at a depth of 0–15 cm. The samples were conditioned and analyzed for pH, particle size, Cation Exchange Capacity (CEC), extractable phosphorus, organic carbon, nitrogen, and exchangeable bases. A comparison of the soil properties between undisturbed sites and charcoaling sites showed significant differences for all chemical properties except CEC, Mg, and K. For the Moiben site, only the pH showed no significant difference (p < 0.05).  The observed high carbon content reduced with time for the one year following charcoaling activity and was attributed to soil erosion since charcoal production activities reduced the sites vegetation cover. Most chemical changes positively enhanced the nutrients content and availability, but were short lived probably due to soil erosion.  These results demonstrate the need to adopt technologies with minimum impact on the soil, or a shift to centralized production sites outside forest ecosystems or farmlands.

<b>Electrocoagulation method for colour removal in tea effluent: a case study of Chemomi tea factory in rift valley, Kenya</b>

A simple and efficient electrochemical method that utilizes two steel electrodes and is capable of reducing the colour of tea effluent prior to its discharge into the river system has been developed. The effects of potential difference, inter-electrode distance, surface area of electrodes to effluent volume ratio (S/V), effluent pH, temperature and effluent dilution on power consumption, were investigated. This method was effective at a potential difference of 24 volts, inter-electrode distance of 5 mm, S/V of 18.2 m²/m³ and effluent pH of 6. Effluent dilution led to increase in power consumption while raising temperatures led to a reduction in power consumption. Electrochemical method reduced COD, BOD and electrical conductivity by 96.6 %, 84.0 % and 31.5 %, respectively but increased pH by 10.32 %. The final pH, EC, COD and BOD values were below KBS maximum contaminant levels. The proposed mechanism in colour removal process was phenol coupling. Phenolic tea colour pigments were oxidized by electrons from ionization of iron to form keto radicals, which polymerized to form a long chain polymer. The polymer was electro-floated to the surface by hydrogen gas generated from the reduction of water and oxidation of theaflavins

Ojunga(Etiegni)_Impact of a Kraft Pulp and Paper Mill Effl uent on

Phytoplankton and macroinvertebrate assemblages were used to assess the impact of a kraft pulp and paper mill effluent in Kenya, on River Nzoia downstream of the discharge point in relation to changes in water quality during May to June and November 2008 (rainy and dry seasons, respectively). Total phosphorus concentration increased from 0.027 mg·L-1 upstream to 0.04 mg·L-1 downstream. Ammonia nitrogen (NH3-N) concentration was 0.51 mg·L-1 upstream and 0.86 mg·L- 1 downstream. Nitrate concentration stood at 1.18 mg·L-1 upstream compared with the 2.23 mg·L-1 downstream. The pH changed from 4.5 to 5.0 upstream to 5.5 to 6.0 downstream, while DO increased from 6.57 to 7.03 mg·L-1 downstream. The BOD5 (biochemical oxygen demand after five days) values remained almost unchanged from 4.63 mg·L-1 upstream to 4.67 mg·L-1 downstream. Taxon composition of phytoplankton and macroinvertebrates correlated with adverse environmental gradients resulting from the mill’s effluent discharge. Overall, there was a shift in composition and abundance of both phytoplankton and macroinvertebrates, with the downstream site recording high numbers of tolerant taxa (i.e., Microcystis sp. and Chironomus sp.). It was recommended that water quality monitoring with effluents of this nature be done using a combination of chemical analysis and biological indicators such as phytoplankton and macroinvertebrate