How to overcome the observed challenges of FSM for safely managed sanitation?

With the recent increase in financial support for Fecal Sludge Management(FSM) from governments, development partners, and philanthropic foundations, several organizations are eager to encourage the use of technology for non-sewered sanitation to accelerate the achievement of SDG 6.2. In terms of addressing safely managed sanitation for environmental sustainability, my observations in FSM programs are not quite convincing. 

To begin with, I think the FSM process diagram is a bit dodgy when it comes to communicating things to others or being understood by an audience. It is described as if it were a flow sheet for wastewater treatment facilities, where sewage once loaded, continuously or intermittently flows through different components and treatment units. That isn't the case with FSM, though.

Second, the City-Wide-Inclusive-Sanitation (CWIS) term has been used as a cover page for a booklet explaining FSM, rather than elaborating on designs holistically as its name suggests.

From the standpoint of environmental conservation, it is inappropriate to encourage double-pit latrines with cesspools or leaching pits since this leads to groundwater contamination. For safely managed sanitation, addressing black water management using FSM approaches alone is insufficient. The FSM projects have completely neglected grey water management for the sake of treating septic waste that is excreted by humans. It is not appropriate to promote FSM in isolation from grey water treatment.

Sewered networks, though costly, directly tap both grey and black water from the source and straightly convey the sewage to wastewater treatment plants for necessary treatment. Therefore, looking for a replacement, as such substituting sewered sanitation by FSM, should ascertain the benefits that the previous can deliver. However, will it be cost-effective if the substitute option, like FSM, is insufficient on its own and needs to be supported by greywater treatment solutions conveyed via closed roadside drains, effective monitoring mechanisms to track desludging trucks, and stringent legal paradigms to check people's behavior? Open roadside drains cause insects to breed, which is an annoyance, a loss of hygiene, and a decline in the visual appeal of communities. It takes more land to manage black and grey water in a household with two separate tanks, and this practice is uncommon.

It is best to discourage the existing stand-alone marketing of FSM. It ought to be more actively supported alongside greywater management choices throughout the whole process, from planning and analysis through design and construction to operation. Furthermore, to prevent environmental pollution and Fecal Sludge Treatment Plants(FSTPs) from running out of sufficient load, conveyance systems and their construction should be made available and closely monitored.

Inevitably, standard design methodologies and mathematical equations for the engineering design of customized FSM treatment processes are urgently required to be developed. To prevent any environmental pollution, on-site research projects on the environmental effects of leaching pits or cesspools should be carried out to comprehend the hydrogeology, soil characteristics, microbiota, and groundwater dynamics. The amount that onsite sanitation contributes to greenhouse gas emissions, including emissions from septic tanks, needs to be carefully calculated and contrasted with alternative of sewered sanitation. Thus, it is possible to promote FSM while maintaining environmental sustainability-technically, socially, and economically.

(This is an open dialogue to promote cross-learning and exchange of ideas and knowledge for the betterment. Any considerations of the information for a purpose other than the mentioned is inadvertent and discouraged.)