The emergence of waterborne viruses with resistance to disinfection has been demonstrated in the laboratory and in the environment. Yet, the implications of such resistance for virus control remain obscure. In this study we investigate if viruses with resistance to a given disinfection method exhibit cross-resistance to other disinfectants. Chlorine dioxide (ClO2)- or UV-resistant populations o...

Background: This study aimed to evaluated trends for iron and manganese concentrations in wells, reservoirs, and water distribution networks in Qom city during the summer of 2012. Methods: This was a cross-sectional study. The studied scopes consisted of groundwater (60 wells), reservoirs (10 tanks), and water distribution network (33 points). One sample was taken from each source monthly. Stat...

Four types of biomass (chicken waste, wood pellets, coffee residue, and tobacco stalks) were cofired at 30 wt % with a U.S. sub-bituminous coal (Powder River Basin Coal) in a laboratory-scale fluidized bed combustor. A cyclone, followed by a quartz filter, was used for fly ash removal during tests. The temperatures of the cyclone and filter were controlled at 250 and 150 degrees C, respectively...

Cyanuric acid is used to stabilize free chlorine to reduce photodegradation in outdoor swimming pools. While there have been numerous studies examining its effect on the disinfection rates of bacteria and viruses, it is not known whether cyanuric acid can significantly impact the effectiveness of hyperchlorination for inactivating Cryptosporidium oocysts present in fecally-contaminated swimming...

The ability of chlorine dioxide (ClO2) to achieve 2-log inactivation of Cryptosporidium in drinking water has been documented. No studies have specifically addressed the effects of ClO2 on C. parvum oocyst infectivity in chlorinated recreational water venues (e.g., pools). The aim of this research was to determine the efficacy of ClO2 as an alternative to existing hyperchlorination protocols th...

Ultraviolet (UV) irradiation is commonly applied as a secondary disinfection process in chlorinated pools. UV-based systems have been reported to yield improvements in swimming pool water and air chemistry, but to date these observations have been largely anecdotal. The objectives of this investigation were to evaluate the effects of UV irradiation on chlorination of important organic-N precurs...

A fluorochemical surfactant was used to reduce the surface tension of 4 per cent sodium hypochlorite from 70 mN/m to 27 mN/m. The solution was stable for more than one month when tested for reduced surface tension, available chlorine, and protein solvent ability. No chemical residue remained on the root canal wall when viewed using scanning electron

Biocide inactivation of Bacillus anthracis spores in the presence of food residues after a 10-min treatment time was investigated. Spores of nonvirulent Bacillus anthracis strains 7702, ANR-1, and 9131 were mixed with water, flour paste, whole milk, or egg yolk emulsion and dried onto stainless-steel carriers. The carriers were exposed to various concentrations of peroxyacetic acid, sodium hypo...

Accurate forecasting of disinfection residuals in a water distribution system (WDS) is essential for optimal control of disinfectant dosing in order to maintain good water quality within the system. The most commonly used disinfectant in the drinking water treatment process throughout the world is chlorine. Previously, artificial neural networks (ANNs) have been used successfully to predict chl...

Chlorine is most readily available in the form of chloride of lime (bleaching powder), which can readily be obtained commercially. This, if freshly made, should contain 33 per cent, of free or active chlorine. It loses its efficacy on keeping, especially during hot weather; but this loss may be retarded by the addition of 25 per cent, of quicklime. Samples of the bleaching powder used should be...