The development of point-of-use treatment technologies for the production of drinking water

Clayton, Gillian

Abstract

An estimated 884 million people worldwide lack access to drinking water from improved water sources. With the global population expected to reach eleven billion by the end of the 21st Century, stress on water and energy resources will be exacerbated. The development and implementation of innovative drinking water treatment technologies ensuring safe, sustainable drinking water provision is required. The overall aim of this thesis was to develop point-of-use [POU] water treatment technologies for the production of chemically and biologically safe drinking water.

A proof-of-concept decentralised drinking water treatment systems [DWTS] investigated whether Drinking Water Inspectorate [DWI] standard drinking water could be produced by combining multi-step filtration processes, including ultrafiltration [UF] membrane columns, and low dosing of electrochemically activated solution [ECAS] dosing pre- and post UF column membrane (total 1% [v/v]). The ECAS dosing regimen produce DWI standard drinking water, whilst the treated water produced in throughout the control (no ECAS dosing) field trial was not biologically safe. Resulting from these trials, further investigations regarding the effect ECAS has on producing chemically (e.g. trihalomethanes [THMs]) and biologically safe water, as well as manage biofilm formation to minimise biofouling. THMs are regulated disinfection products [DBPs], and form through chlorine-based disinfectants reacting with organic matter. Comparing THM formation in water when treated with three disinfectants (ECAS, NaOCl and HOCl) as a function of contact time and free chlorine resulted in NaOCl producing significantly higher concentrations compared to HOCl and ECAS.

Chlorination processes in drinking water treatment ensure the production of biologically safe water. The comparative antimicrobial activity of ECAS against NaOCl and HOCl against standard microbial challenges in planktonic phase, and as biofilms was determined. Throughout all standard chemical bactericidal assays against planktonic E. coli ATCC 10536, neutral (HOCl) and acidic (ECAS) disinfectants exhibited greater antimicrobial activity in comparison to NaOCl, the alkaline disinfectant (NaOCl). Increasing organic load resulted in reduced antimicrobial activity for all disinfectants tested. The antimicrobial activity of all disinfectants decreased against a mature Pseudomonas aeruginosa ATCC 15422 biofilm. ECAS demonstrated the greatest reduction in biofilm density compared to NaOCl and HOCl at free chlorine concentrations ≥ 50 mg L-1. In-situ disinfectant dosing biofilm models to represent disinfection processes in water treatment were developed. Preliminary experiments demonstrated an inhibitory effect against biofilm formation through in-situ dosing, however, further model development and experimentation is required.

• Thesis Type: Thesis
• Publicly Available Date: Nov 4, 2019
• Public URL: https://uwe-repository.worktribe.com/output/1490721
• Award Date: Nov 4, 2019