Field testing of an onsite sanitation system on apartment building blackwater using biological treatment and electrochemical disinfection

Abstract

Demonstration of an electrochemical toilet wastewater treatment and disinfection technology at the scale of an apartment building and translation of the system into a commercial product.

Resolving the relative contributions of cistern and pour flushing to toilet water usage: Measurements from urban test sites in India

“…The large fraction of pour flushing water present in blackwater should also inform the design of onsite blackwater treatment systems for these types of markets. As a direct consequence of this study, the CLASS electrochemical blackwater treatment prototype was redesigned to include automated brine injection because of the dilution of reused water feeding toilet cisterns with pour flush water ( Varigala et al, 2020 ).…”

“…Toilet flush water volumes from cistern and from the personal wash tap were measured in connection with the operation of two different treatment technologies in three separate test sites. The Kohler CLASS (Closed Loop Advanced Sanitation System; Kohler Co., Wisconsin, USA) technology was designed to treat blackwater in aggregate from multiple toilets in an apartment building ( Varigala et al, 2020 ). The Duke blackwater treatment system (Center for WaSH-AID, Duke University, North Carolina, USA) was designed to be connected to a single toilet stall for a shared toilet ( Welling et al, 2020 ).…”

Optimal design of an electrochemical reactor for blackwater treatment

“…System installation description CLASS prototypes were installed at the ground level outside of two separate apartment buildings in Coimbatore, Tamil Nadu, India. A detailed description of the flow through the CLASS system has been published elsewhere (Varigala et al, 2020). In each building, the toilet effluent (blackwater) was piped separately from the rest of the apartment's wastewater pipes.…”

“…An improved biological pretreatment subsystem was added to the CLASS v2 prototypes to increase COD and the NH 3 removal prior to electrolysis (Varigala et al., 2020), and the ECR was redesigned based on this reduced treatment load. The number of electrode stacks was reduced from 7 stacks ( S A = 9.4 m 2 ) to 2 stacks ( S A = 2.5 m 2 ), and the effective treatment volume was increased to V ECR = 62 L. This resulted in r VS = 25 L/m 2 for the CLASS v2 prototypes compared with r VS = 5.8 L/m 2 for CLASS v1.…”

“…Details on the performance testing of the two CLASS versions, overall energy estimates for the improved version, and complete description of the flow through CLASS system have been described elsewhere (Varigala et al., 2020; Welling et al., 2020).…”