Use of Ozone for Disinfection and Taste and Odor Control at Proposed Membrane Facility

Abstract

Zone 7 of Alameda County Flood Control and WaterConservation District, in coordination with Black & Veatch, conducted a 9-month pilot study to determine preliminary design parameters for a new water treatment plant (WTP). The pilot study was performed to verify the performance of membrane filters and to establish preliminary design parameters for the submerged membrane process, followed by ozonation and biological granular activated carbon filtration. The pilot testing was conducted using water from the Patterson Pass WTP reservoir. The process included coagulation with either ferric chloride or polyaluminum chloride, flocculation, sedimentation, membrane filtration, ozonation, and filtration using biological granular activated carbon (BAC). The goals of the study were as follows:1. Determine the potential effectiveness of ozone and BAC for removing geosmin and MIB. 2. Determine the impacts of different levels of pathogen inactivation, i.e., 0.5-log Giardia and 2-log virus inactivation. 3. Monitor the formation of bromate under various conditions of ozone oxidation for different levels of pathogen inactivation as well as for taste and odor control, and evaluate bromate mitigation strategies, if necessary.The results of the study showed that the use of ozone achieved 2.0-log virus inactivation and 0.5-log Giardia inactivation. It also decreased the disinfection by-product formation and effectively controlled geosmin and removed a significant fraction of the MIB during a taste and odor event. Because the raw water bromide concentrations were low, bromate formation remained below the regulated level of 0.010 mg/L. However, in one instance, bromate mitigation was utilized by applying sulfuric acid to lower the pH to less than 7.1, which reduced bromate formation to less than 0.010 mg/L.

The virus removal in UV irradiation, ozonation and chlorination

“…The oxidative reaction is very quick. Generally, the concentration of residual ozone is halved in the first 30 ​s [ [26] , [27] , [28] ] and reaches at least a 1-log inactivation [ 29 ]. It is reported that oxidation of proteins by ozone mainly occurs at the tyrosine, tryptophan, histidine, cysteine, and methionine residues, resulting in the abnormal folding ability and changed higher order structures [ 30 ].…”

“…High temperature reduces the solubility of ozone in water, accelerates the decomposition of ozone but also the disinfection process. In common temperature range between 5 and 30 ​°C, a rise in temperature increases the efficiency of ozone disinfection and decreases the CT value [ 25 , 26 , 36 ]. The temperature coefficient is applied to describe the fold reduction of CT values induced by a 10 ​°C decrease.…”

“…In that case, the ozone disinfection efficiency is compromised because the turbidity-inducing substance brings more ozone demand as DOC [ 53 ]. Bromide and iodide ions also lower the efficiency by consuming ozone to form bromate and iodate, but lowering pH can effectively reduce these side reactions [ 26 ]. Different strains of viruses may have different resistance to ozone.…”

Experimental Tests for Ozone Disinfection Treatment In a Small Backyard Swimming-Pool

“…In some applications ozone is preferred because of its minor odour effect at low concentrations, its colour and taste absence and its effective viral inactivation potential [13,14]. But above all ozone appear an excellent microbicide, because good sanitary efficiencies are obtained with small doses of ozone and short treatment application time [15].…”

Optimization of Mixing and Mass Transfer in In-line Multi-Jet Ozone Contactors Using Computational Fluid Dynamics

“…A typical ozone application is for odor control (Edwards-Brandt et al 2007), specifically the removal of hydrogen sulfide from well water for odor control (Duranceau et al 2010). Hydrogen sulfide (H 2 S) is oxidized rapidly with ozone to form sulfate.…”