This article evaluates the physical-chemical parameters of Faecal Sludge (FS) as possible predictors of dewatering performances. Also, the variability of FS dewatering characteristics was assessed from different containments and in different seasons in relationship with dewatering performance. A total of 120 samples were analyzed were collected and analyzed during the rainy and dry seasons in April and July 2019, respectively to capture season variability. FS from pit latrine (PT) took longer to dewater followed mixer containments, while soak-away sludge (SO) took a relatively short time to dewater. Also, FS from PT was found to have high amount of settled solids hence high % of TS in dry cakes. Slow dewatering and turbid supernatant corresponded to high pH, Electrical conductivity and Total solids, but cake solids after dewatering were correlated with Total solids of FS. The FS dewaterability was higher for SO (DI = 0.9) and least for PT (DI = 0.3). Seasonal variability of FS dewaterability within the containments was higher for PT (DI = 0.74) and least for SO (DI = 0.5). Planning of FS treatment plants including sizing and design for effective dewatering performance, variation of physical-chemical dewatering predictors in sources and season could provide a relatively low-cost way to predict dewatering performance.

Moringa Oleifera (MO) is a highly effective conditioner in the dewatering of Fecal sludge (FS). However, the model for the prediction of its optimal dose has not yet been documented. This article presents the results of the developed model for the prediction of MO optimal doses. The developed model was based on assessing the FS parameters and MO stock solution. The FS samples were obtained from a mixture of a pit latrine and septic tank and were analyzed at the water quality laboratory of the University of Dar es Salaam. The multiple linear regression model was used to establish a relationship between MO optimal dose as a function of FS characteristics (pH, Electrical Conductivity, Total Solids and Total Suspended Solids) and concentration of MO stock solution. The results indicated that the main contributing factors which determine the MO optimal dose were the concentration of MO stock solution, followed by pH of FS. The model results showed a good agreement between the predicted and observed MO optimal dose with a coefficient of determination of R2 = 0.72 and 0.9 for calibration and validation respectively. Therefore, the model can be adapted to determine the MO optimal dose without running the Jar-test experiment.

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Worldwide, every day human beings generate millions of tons of Faecal Sludge (FS), which is rich in water, nutrients, energy, and organic compounds. Yet FS is not being managed in a way that permits us to derive value from its reuse, while at the same time, millions of farmers struggle with depleted soils and lack of water. In most of the developing countries, energy for cooking is mainly derived from cutting of trees, either as wood or charcoal. Resource recovery and reuse from FS can create livelihoods, enhance food security, support green economies, reduce waste and contribute to cost recovery in the sanitation chain. Many studies have reported on the different technologies used for FS treatment, such as dewatering and bio-stabilization. The commonly used dewatering technology is sand drying bed, which occupied a large space and has a low dewatering rate. To enhance the dewatering rate of FS as well as reducing the size of the sand drying bed, the use of chemical conditioners has been done. Despite the fact that they have been used successfully, chemical conditioners are expensive, have health and environmentally hazardous. In recent years, attempts have been made to use local conditioners to tackle the drawbacks experienced from chemical conditioners. Although the feasibility of applying local conditioners for FS dewatering has been studied, its potentials on FS treatment have not been well documented. This review indicates that there is potential for local conditioners linked with dewatering, enhancing of FS resources recovery and in reducing costs of operating and maintaining FS treatment plant. Moreover, local conditioners have the potential in contribution to socio-economic development in Tanzania through renewable energy production, income generation and food- health security, soil and water conservation, eco-sanitation and reduction of environmental degradation.