Faecal sludge characterisation for enhanced sanitation provision in peri-urban areas of Lusaka.

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Tembo, James Madalitso
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The University of Zambia
Lusaka city has over 70 percent of its population residing in peri-urban areas where more than 90 percent of the residents rely on pit latrines for excreta disposal. However, no Faecal Sludge Management (FSM) systems exist to manage the faecal sludge from these facilities. This situation results in faecal sludge ending up in the environment where it contributes to environmental degradation. The design of adequate FSM facilities requires availability of comprehensive faecal sludge quality data in addition to data on quantities. Non availability of the faecal sludge quality data for the city of Lusaka was therefore the main reason why this study was conceived. The study evaluated in detail, the sanitation practices in peri-urban areas that impact on faecal sludge quality, including faecal sludge quality characteristics that would impact on valorisation. The study also assessed the variability of the faecal sludge quality with depth and geological formations. Sanitation practices were evaluated through both qualitative and quantitative methods involving observations and Focus Group Discussions (FGDs) and household questionnaires. Data for the other aspects was collected using field surveys and laboratory experiments. A total of 100 pit latrines to serve as sampling points were selected using a stratified purposive sampling method. A total of 28 parameters falling within the physical, chemical, rheological and microbiological categories were analysed. Among the major findings were the following: there was no regulation on the design, construction and usage of sanitation facilities in peri-urban areas leading to practices that compromised the faecal sludge quality; the faecal sludge was found to have high valorization potential assessed from the high organic matter and nutrient content and low concentration of inhibitory substances. For the analysed top and bottom sludge samples, Total Volatile Solids (TVS) averaged 0.63±0.145 and 0.55±0.107g/g dry solids, Total Chemical Oxygen Demand (COD) averaged 129,407±55,088 and 112,052±51,467 mg O2/L, and Biochemical Oxygen Demand (BOD) averaged 1,045±527 and 1,006±470 mg O2/L, respectively. Microbiological parameters generally recorded high counts with the prevalence of viable Ascaris at 27 percent (n=100); there were statistically insignificant differences with depth among the means of the various parameters indicative of biodegradation except for TVS (p=0.0005), Viable Ascaris (p=0.0021) and Cryptosporidium (p=0.0002); and variability of the faecal sludge quality with differences in geological characteristics of the study areas analysed revealed statistically marginal differences for most of the parameters including Total COD (p=0.05). The statistically insignificant differences in the quality of faecal sludge quality with respect to depth and geological formations implies that universal measures could be instituted in the management of the sludge without giving consideration to the source. Based on the results, a responsive Operations Framework for enhanced FSM service delivery integrating faecal sludge quality with reuse initiatives, regulation and awareness creation was proposed. Some of the recommendations included replication of the study to cover the rain season and also evaluating the feasibility of the faecal sludge reuse initiatives from the local social-cultural perspective as this is a cardinal aspect in the operationalisation of the proposed framework.
Thesis of Doctor of Philosophy in Environmental Engineering.