News
Our novel PV-chlorinator delivers treated water from a contaminated well with no brought-in chemicals for the first time.
September, 2022
Our novel PV-powered chlorinator has successfully treated contaminated groundwater from an old village well close to our R&D base in Oxford, UK, under a range of operational conditions, for the first time.
Our Direct Contact Chlorinator (DCC) technology involves a novel approach to direct electrolysis of untreated groundwater to liberate naturally-present dissolved chlorides as free chlorine. The tests, conducted entirely off-grid, involved treating well-water contaminated with coliforms including e-coli to a target free-chlorine concentration of 2.65ppm. This was done without adding any treatment chemicals or sourced-reagents. These tests also demonstrated that our approach is capable of treating water with rapidly varying flowrate and power availability, consistent with varying power levels and flowrates associated with point-of-use treatment in off-grid/weak-grid public buildings, at community water sites, and in small piped-water networks in the global south.
The trials further provided early verification of our approach to field-calibration (to achieve a target chlorine concentration without prior knowledge of water composition), and failure mode mitigation (predominantly to ensure that only safe water is delivered). Our 2.65ppm target was maintained to within to within 10% of the target value throughout the tests.
Our next challenge is to demonstrate this capability with a variety of groundwater sources in the UK, of significantly varying and unknown chemical solute composition, before packaging the technology up and shipping it out for field trials with our partners in southern Asia and sub-Saharan Africa. Our desk-research indicates that this approach to chlorination is probably viable in approximately one third of water wells in the UPGro database; a publicly available resource covering over 400 wells distributed across Malawi, Ethiopia and Uganda.
We will soon begin work to be able to treat water at most of the two thirds of UPGro sites not suited to this approach, with a Hypochlorite Generator Accessory (HGA). The HGA will automatically treat source water using crystalline common salt as its only feedstock material.
Chlorination is by far the most common water sterilisation method used worldwide, and the only method providing residual protection against microbial contamination post-source. This is increasingly understood to be as significant as contamination at source, particularly when water is collected in buckets or jerricans and carried to the home. However, its implementation is currently hindered by limited supply chains for chemical feedstocks, dependence on skilled operators, and routine service/maintenance requirements.
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