A methodology for the evaluation of disinfection technologies

Abstract

There are several concerns associated with the use of chlorine for potable water disinfection. These are the resistance of certain pathogens, the formation of toxic disinfection by-products and the adverse effects on aesthetic water quality. Owing to these concerns the water industry is continually reviewing alternative disinfection technologies. A methodology has been devised that will aid the water industry in evaluating the potential of these technologies. The methodology uses seven criteria to evaluate the technologies, these are: inactivation efficiency, disinfection byproduct (DBP) formation, toxicity, aesthetic water quality, cost, scalability and residual maintenance. Each criterion is assessed by associated questions in order of importance in accordance with a protocol. The criteria are evaluated using UK water quality regulations as standards. Ultraviolet (UV) disinfection was used as an example to demonstrate the methodology. UV was shown to meet all the criteria apart from the provision of a residual disinfectant. Several other disinfection technologies were evaluated using the methodology. Direct electrochemical disinfection and mixed oxidant generators were identified as having the most potential for replacing chlorination.

Selection Criteria for Water Disinfection Techniques in Agricultural Practices

“…Capital investments to acquire the necessary equipment are supplemented by amortization costs, site specific constraints, and hiring consultants in order to implement the technology. Operational costs should be calculated in cost per cubic meter of treated water (USEPA, 1986;Kerwick et al, 2005) and include cleaning chemicals, supplies and other maintenance costs, equipment repairs, the storage of chemicals and spare parts, operator and management personnel costs, training of personnel, and power consumption (USEPA, 1986;Tzimas et al, 2006). Furthermore, shifts in the market situation influence total costs (Liberti et al, 2000b).…”

“…Cost-effectiveness also depends upon the water quality, the needed pre-treatment, the imposed/aspired level of safety, the degree of automation, and local labor costs. During the evaluation of the scale-up from concept to a large operational process, care must be taken when extrapolating costs (Collivignarelli et al, 2000;Kerwick et al, 2005).…”

“…Future environmental and social implications are of importance when evaluating possible disinfection technologies for replacing chlorination. The impact of factors such as the generation and use of energy, transportation and storage of hazardous chemicals, and disposal of caustic chemicals and contaminated backwash from membrane processes should be considered (EPA Victoria, 2002;Kerwick et al, 2005).…”

Modeling of ultraviolet (UV) radiation under a large pilot-scale designed for wastewater disinfection and inactivation of selected bacteria of Pseudomonas aeruginosa in a laboratory UV device

“…During this period, the decrease rate of number of bacteria is not measurable and quantifiable. This fact was observed for Escherichia coli in the presence of chlorine dioxide taken as disinfectant (Kerwick et al, 2005). The latency period may also be due to the probability of contact between the disinfectant molecules and microorganisms present in water as conglomerates of different sizes (Mounaouer and Hassen, 2011).…”

A thin layer electrochemical cell for disinfection of water contaminated with Staphylococcus aureus

“…Experiments comparing the performance of anodic materials have been carried out with oxide electrodes (13,2), activated carbon fiber (12), platinum-clad niobium mesh (10), palladium-coated carbon cloth (19), doped diamond (17), etc. However, most of these materials are only conventional for scientific purposes, but not available in large-scale or economically appealing engineering applications.…”