Optimal design of an electrochemical reactor for blackwater treatment

• Published in: Water environment research Vol. 93; no. 1; pp. 148 - 158
• Main Authors: Varigala, Siva, Krishnaswamy, Srinivas, Lohia, Chandra P., Hegarty‐Craver, Meghan, Grego, Sonia, Luettgen, Michael, Cid, Clement A.
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01-01-2021; John Wiley and Sons Inc
• Subjects: Automation; Blackwater; blackwater treatment; Chlorine; Cities; Cleaning; Computer applications; Design optimization; Disinfection; Dynamic analysis; Electrochemistry; electrode cleaning; Electrodes; Electrolysis; Flaking; Injection; Maintenance; mineral deposits; Nutrient removal; Polarity; Precipitates; Reactor design; Reactors; reverse polarity; Toilets; uniform mixing; Waste Disposal, Fluid; Waste Water; Wastewater treatment; Cities; blackwater treatment; electrode cleaning; mineral deposits; uniform mixing; reverse polarity
• ISSN: 1061-4303; 1554-7531
• DOI: 10.1002/wer.1374

Electrolysis of blackwater for disinfection and nutrient removal is a portable and scalable technology that can lessen the need for cities to construct large‐scale wastewater treatment infrastructure and enable the safe onsite reuse of blackwater. Several systems for treating wastewater from single toilets are described in the literature, but there are few examples of systems designed to use electrolysis to treat blackwater from nearby toilets, which is a situation more common in densely packed urban living environments. In order to scale a single toilet electrolysis system to one that could service multiple toilets, computational fluid dynamic analysis was used to optimize the electrochemical reactor design, and laboratory and field‐testing were used to confirm results. Design efforts included optimization of the reactor shape and mixing to improve treatment efficiency, as well as automated cleaning and salt injection to reduce maintenance and service requirements.
Practitioner points
Design of a reverse polarity mechanism to enable in situ electrode cleaning and improve long‐term electrode performance.
Optimization of a hopper design and drainpipe location to collect and remove flaking precipitates and mitigate maintenance issues.
Design of an automated salt injection system to guarantee sufficient chloride levels for producing adequate chlorine residuals for consistent disinfection.
Optimized electrochemical reactor for blackwater treatment.