The role of emptying services in provision of safely managed sanitation: A classification and quantification of the needs of LMICs.

Classifications for onsite sanitation in terms of facility type (septic tanks, pit latrines) exist, but connecting these facilities to the wider sanitation value chain via improved containment, emptying, and collection has not been well explored. Using existing Joint Monitoring Programme facility classifications and secondary data on piped water access, a Service Typology was developed to classify and quantify the primary emptying service needs of household level onsite sanitation facilities. Facilities in six Sustainable Development Goal (SDG) regions were classified as Emptiable (faecal sludge can be removed either via Mechanized or Non-Mechanized means) or Unemptiable. Of the 722 million household level sanitation facilities assessed in these regions, 32% were found to be emptiable via Mechanized means, 50% via Non-Mechanized means and 18% were found to be Unemptiable pits. The volume (by number of facilities) and density (as a proportion of the full population) of each service type were estimated by SDG region and by country. Results from this study provide background data on the role of emptying sanitation facilities in achieving SDG6, and can be incorporated into investment priorities, policy framing, technology development, infrastructure development, and targeted behaviour change strategies.

A granular activated carbon/electrochemical hybrid system for onsite treatment and reuse of blackwater.

Over 1/3 of the global population lacks access to improved sanitation, leading to disease, death, and impaired economic development. Our group is working to develop rapidly deployable, cost-effective, and sustainable solutions to this global problem that do not require significant investments in infrastructure. Previously, we demonstrated the feasibility of a toilet system that recycles blackwater for onsite reuse as flush water, in which the blackwater is electrochemically treated to remove pathogens due to fecal contamination. However, this process requires considerable energy (48-93 kJ/L) to achieve complete disinfection of the process liquid, and the disinfected liquid retains color and chemical oxygen demand (COD) in excess of local discharge standards, negatively impacting user acceptability. Granular activated carbon (GAC) efficiently reduces COD in concentrated wastewaters. We hypothesized that reduction of COD with GAC prior to electrochemical treatment would both improve disinfection energy efficiency and user acceptability of the treated liquid. Here we describe the development and testing of a hybrid system that combines these technologies and demonstrate its ability to achieve full disinfection with improved energy efficiency and liquid quality more suitable for onsite reuse and/or discharge.

Improving energy efficiency of electrochemical blackwater disinfection through sequential reduction of suspended solids and chemical oxygen demand.

Onsite reuse of blackwater requires removal of considerable amounts of suspended solids and organic material in addition to inactivation of pathogens. Previously, we showed that electrochemical treatment could be used for effective pathogen inactivation in blackwater, but was inadequate to remove solids and organics to emerging industry standards. Further, we found that as solids and organics accumulate with repeated recycling, electrochemical treatment becomes less energetically sustainable. Here, we describe a pilot study in which concentrated blackwater is pretreated with ultrafiltration and granular activated carbon prior to electrochemical disinfection, and show that this combination of treatments removes 75-99% of chemical oxygen demand, 92-100% of total suspended solids, and improves the energy efficiency of electrochemical blackwater treatment by an order of magnitude.