Air quality assessment of carbon monoxide, nitrogen dioxide and sulfur dioxide levels in Blantyre, Malawi: a statistical approach to a stationary environmental monitoring station

Air quality in urban areas is a cause of concern because of increased industrial activities that contribute to large quantities of emissions. The study assess levels and variations of carbon monoxide (CO), nitrogen dioxide (NO2) and sulfur dioxide (SO2) in Blantyre, Malawi using a stationary environmental monitoring station (EMS). Results show that CO level (2.47 ± 1.23 mg m-3) were below the Malawian limit value (10.31 mg m-3). Although, NO2 (4.02 ± 2.47 mg m-3) and SO2 (8.58 ± 2.88 mg m-3) were significantly higher than allowable Malawian Standards (0.52 and 0.23 mg m-3, respectively). Discernible variations in hourly, diurnal, monthly and seasonal CO, SO2 and NO2 were apparent. Independent t-test confirmed that day time values were higher than those at night (p < 0.05). Thus, variations in local weather affect the disparity in hourly and diurnal values. Analysis of variance (ANOVA) confirmed significant variations in monthly observations. Moreover, independent t-test showed that wet season CO (2.32 mg m-3), SO2 (5.10 mg m-3) and NO2 (9.41 mg m-3) levels were higher than dry season values (CO = 2.32 mg m-3; SO2 = 3.42 mg m-3; NO2 = 8.13 mg m-3). A hierarchical cluster analysis (HCA) divided the 10 months into three groups based on distribution of CO, SO2 and NO2, air temperature, wind speed and wind direction. Furthermore, factor analysis (FA) showed that air temperature had significant contribution to variations in mean values of CO, SO2 and NO2 for the entire study period. The study shows a need for constant urban air quality monitoring in Blantyre and all urban areas in Malawi. It is recommended that the experimental site widen the scope of the study by utilizing the flexibility of the EMS. Key words: Air pollutants, principal component analysis, developing countries, environmental monitoringstation, Kaiser normalization

Assessment of changes in drinking water quality during distribution: A case study of Area 25 Township in Lilongwe, Malawi

The quality of drinking water at the point of delivery to the consumer is crucial in safeguarding people’s health. This study assesses changes in drinking water quality during distribution at Area 25 Township in Lilongwe, Malawi. Water samples were collected from the exit point of the treatment plant, storage tank and taps at consumers’ households. All samples were tested using standard procedures for pH, turbidity, feacal coliforms, manganese, lead, zinc and residual chlorine. One-way ANOVA showed some significant water quality changes during distribution but the average values fell within World Health Organisation (WHO) and Malawi Bureau of standards (MBS) allowable levels for pH, turbidity, feacal coliforms, manganese, lead, zinc and residual chlorine (p < 0.05). Tap water at Area 25 Township is generally safe for human consumption.Key words: Drinking water, distribution system, biochemical parameters, human health

Effect of heat moisture treatment on physicochemical and pasting properties of starch extracted from eleven sweet potato varieties

Starch separated from eleven sweet potato varieties was subjected to heat moisture treatment (HMT) at 30% moisture and 110°C for 3 hours. Following HMT, there were no significant changes in physicochemical properties of the starches. This was attributed to limited moisture content (30%) to influence hydration that could consequently alter granule morphology. Further, chemical parameters such as amylose content, pH and phosphorus were not affected because HMT is a physical treatment. In contrast, HMT caused changes in the packing arrangement of the polymer chains leading to enhanced intragranular binding. Alteration of the internal organisation of the granules caused significant changes in pasting properties of the starches such as pasting time, pasting temperature, peak viscosity, hot paste viscosity, cold paste viscosity, breakdown, set back and stability ratios. The findings provide evidence that functionality of sweet potato starch can be altered to suit a particular industrial need

Physicochemical and pasting properties of starch extracted from eleven sweetpotato varieties

Physicochemical and pasting properties of starch extracted from eleven sweetpotato varieties wereevaluated. Relationships between starch properties were determined using correlation analysis.Significant differences were revealed among the physicochemical properties such as amylose, pH,granule size and size distribution. According to the Rapid visco analyzer (RVA) viscosity profiles, allstarches exhibited a type A profile which is characterized by high peak viscosity followed by majorbreakdown. However, significant differences were observed in individual pasting parameters such aspasting time, hot paste viscosity, cold paste viscosity, stability ratio, setback ratio and breakdown. Theresults revealed that variety has an effect on composition and pasting properties of sweetpotato starch.Correlations developed in this study were useful in predicting starch functionality when applied in foodindustry