Low-cost solar septic tanks as sustainable sanitation solution: a case study implemented in Cambodia

The integration of a solar septic tank (SST) system with an economically viable solar water-heating apparatus comprising polyethylene (PE) and copper (Cu) pipes, as well as a lightweight structural framework, has been conceptualized and implemented. Two variants of low-cost SSTs were subjected to empirical scrutiny within authentic settings, encompassing public toilets and residential establishments in Cambodia. Both the PE pipe and Cu pipe solar water-heating devices demonstrated efficacy in consistently maintaining temperatures within the system above ambient levels. Although the parameters do not conform to Cambodia's effluent requirements, the results of this study suggest that the SST is effective in reducing organic loads and provides a significant improvement over conventional septic tank effluent. This underscores the potential applicability of the developed system for the treatment of toilet wastewater, thereby mitigating pollution concerns and public health risks. Harnessing solar energy to elevate septic tank temperature, this system's cost varies but includes materials, tools, and miscellaneous components, with a total estimated cost ranging from $600 to $2500, depending on size and complexity.