Anaerobic effluent disinfected with ozone/hydrogen peroxide (original) (raw)
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Disinfection of anaerobic/aerobic sanitary effluent using ozone: formaldehyde formation
Water Environment Research, 2019
The scarcity of natural resources supports the perspective of reusing treated effluents, mainly in agriculture, where the reduction in the demand of drinking water and the provision of alternative sources for nutrients are important. However, the process of disinfection, essential to the protection of human health, generates deleterious byproducts to both humans and the environment. This research aimed to evaluate the use of ozone as a disinfectant for wastewater treated by anaerobic/aerobic baffled reactor for later agricultural reuse. Disinfection tests were conducted by applying ozone, in batch, with applied dosages of 5, 8, and 10 mg O 3 /L and contact time of 7 min. All the tests led to formaldehyde formation, therefore within the standard suggested by the World Health Organization. For the indicators total coliforms and Escherichia coli, the ozone was considered effective, satisfying the criteria for agricultural reuse according to the World Health Organization of a dosage of 8 mg O 3 /L.
Wastewater disinfection by ozone
Wastewater disinfection by ozone was investigated at pilot scale on different wastewater effluents. Variations in operating conditions showed that a very low hydraulic retention time (2 min) was sufficient for efficient fecal coliform inactivation, provided a sufficient ozone dose was transferred to the effluent. Therefore, the transferred ozone dose appeared to be the critical parameter for the design of wastewater disinfection. As a consequence, the ''Ct'' approach commonly applied in drinking water treatment should not be used for wastewater ozonation. Design parameters of ozonation were proposed for two types of regulations, and for effluents of different qualities. It was demonstrated that only with an efficient filtration step one can meet stringent standards such as the California Title 22 criteria. In all cases, viruses were totally inactivated; consequently, viruses do not constitute a limiting factor in wastewater disinfection by ozone.
Ozone: Science & Engineering, 2018
Performance of ozonation and an ozone/hydrogen peroxide process under a new concept centering on ozonation and/or ozone/hydrogen peroxide processes in sewage treatment processes comprising only physical and chemical processes are discussed, with focus on the removal of matrix organic compounds and emerging contaminants. Matrix organic compounds of filtrated primary sewage effluents were removed to as low as 3.2 mgC/L in the ozone/hydrogen peroxide process at an ozone consumption of around 400 mg/L. Linear relationships between ozone consumption and removal amounts of organic compounds were observed, in which the amounts of ozone required to remove 1 mg of organic carbon were 9.5 and 8.3 mg (2.4 and 2.1 mol-O 3 / mol-C) in ozonation and the ozone/hydrogen peroxide process, respectively. Ratios of hydroxyl radical exposure to ozone exposure were in the order of 10-9 to 10-8 for ozonation and 10-7 to 10-6 for the ozone/hydrogen peroxide process. Experiments and a kinetic evaluation showed that ozonation and/or the ozone/hydrogen peroxide process have high elimination capability for emerging contaminants, even in primary sewage effluent with the thorough removal of matrix organic compounds. Newly found reaction phenomena, the temporal increase and decrease of dissolved ozone and accumulation of hydrogen peroxide in the early stage of oxidation with the continuous feeding of hydrogen peroxide, were presented. Possible reaction mechanisms are also discussed.
Water Research, 1997
The oxidation of two wastewaters with ozone combined with hydrogen peroxide or UV radiation (2~;4 nm) has been studied. The oxidation yields of these systems were compared with those from ozonation alone at similar experimental conditions. It was found that O3/H202 oxidation leads to important increases in COD degradation rate (i.e. 86% at pH 6 in tomato wastewaters). The differences between the oxidation types (03 and O3/H202) diminish with increase in pH. With distillery wastewaters the presence of hydrogen peroxide hardly increases the oxidation rate. However, the combination of O3/UV radiation was the best oxidation method applied because of the improvements achieved in both COD and TOC disappearance rates compared to those of ozonation alone, regardless of wastewater type treated. As happened with other oxidation systems, the COD and TOC reductions were higher in tomato wastewater oxidation. Different kinetic parameters were also determined in order to quantify the reactivity of wastewaters towards the oxidation systems applied. © 1997 Elsevier Science Ltd
Journal of Waste Water Treatment & Analysis, 2011
Present study was conducted to evaluate the impact of ozonation on the quality improvement of Secondary Treated wastewater at Varanasi, in India. Physico-chemical parameters such as BOD, COD, TOC, UV 254 , color and microbiological parameters such as E. coli, fecal coli. & total coliform disinfection parameters were used to evaluate the efficiency of ozone to upgrade secondary effluent quality. Experimental results revealed that 10 mgL-1 O 3 for 5 minutes exposure duration was found most suitable dose and contact time for the significant reduction of physicochemical parameters of secondary treated wastewater such as BOD, COD, TOC, UV 254 and color i.e. 30%, 14.3% 45% & 60% respectively as well as it enhanced the biodegradability more than 50% in the treated water. Our data also revealed that this applied dose and exposure time is responsible for the highest degradation of microbiological parameters i.e. >98%. Other than this the toxic response of test species was influenced mainly by the dose and exposure time. The acute toxic effect after ozonation was observed on V. fischeri and found that toxic effect of the secondary effluent was decreased after applied dose and exposure duration. Results supported the expectation that the process of Ozone might enhance the overall treatment efficiency of secondary effluent treatment.
Disinfection of recycled red-meat-processing wastewater by ozone
Journal of Chemical Technology and Biotechnology, 2005
Ozonation of a real red-meat-processing wastewater was conducted in a semi-batch reactor to explore the possibility of the water reuse. The experimental results revealed that ozone was very effective in disinfection of the red-meat-processing wastewater. After 8 min of ozonation with an applied ozone dose of 23.09 mg min−1 liter−1 of wastewater, 99% of aerobic bacteria, total coliforms and Escherichiacoli were inactivated. Empirical models were developed to predict the microbial inactivation efficacy of ozone from the CT values for the real red-meat-processing wastewater. A correlation was also derived to estimate the CT values from the applied ozone dose and the ozone contact time. The results also revealed that under the ozonation condition for 99% inactivation of aerobic bacteria, total coliforms and E coli, the decrease in the chemical oxygen demand and the 5-day biological oxygen demand of the wastewater were 10.7% and 23.6%, respectively. However, ozonation under this condition neither improved the light transmission nor reduced the total suspended solids (TSS) despite of the decolorization of the wastewater after ozonation. Copyright © 2005 Society of Chemical Industry
Pilot Plant Investigation of Ozone Disinfection of Physico- Chemically Treated Municipal Wastewater
An ozonation pilot plant was installed at the Montréal Urban Community Wastewater Treatment Plant (MUCWTP) to assess the feasibility of employing a full scale ozone disinfection system. Wastewater characteristics such as turbidity, COD, TOC, BOD, pH, ORP and suspended solids were monitored to assess their effect on ozone disinfection. Fecal conforms (FC) were used as indicators to measure disinfection performance. Ozone disinfection was capable of reducing the fecal conform counts from typical 0.4 - 4 million CFU/100 ml to thousands, hundreds or tens per 100 ml depending on the dose applied. None of the parameters monitored could be correlated with the ozone dose required to achieve particular disinfection efficiency. Pilot tests showed that an ozone dose of 17 mg/l reduced the percentage of cases (observed in this study) for which the concentration of FC in the effluent was higher than 5000 CFU/100 ml (as required by the Quebec Ministry of the Environment) to 10%. A dose of 20 mg/l...
Application of ozone based treatments of secondary effluents
Bioresource Technology, 2011
The present work was aimed at studying the efficiency of ozone in oxidation processes, coliform inactivation and Disinfection Byproducts (DBPs) formation, associated with the potential of ozone to increase the Biodegradable Dissolved Organic Carbon (BDOC) in secondary effluent with applied ozone doses of 5.0, 10.0 and 15.0 mg/L for contact times of 2, 5 and 10 min. The wastewater used in this work was collected from the Bhagwanpur Sewage Treatment Plant, Varanasi, India. Results of this experiment showed that 10 mg O 3 /L O 3 for 5 min exposure was found most suitable dose for highest degradation of COD, TOC, UV 254 , color, turbidity and total nitrogen parameters. The inactivation range of microbial biomass range was found in between 95% and 98%. Experiment revealed the fact that aldehydes and carboxylic acid formation were significantly related with the ozone dose and exposure time and ozone might enhance the treatment efficiency of secondary effluent treatment.
Applications of ozone for modern wastewater treatment
International Journal of Environmental Engineering, 2012
Modern Wastewater Treatment Plants (WWTPs) effi ciently eliminate organic pollution down to Biological Oxygen Demand (BOD) and Suspended Solids (SS) values of less than 30 mg/l. However, these treated effl uents still contain biologically Persistent Organic Matter (POM), characterised by a Chemical Oxygen Demand (COD) of between 50 and more than 100 mg/l. Industrial WWTP effl uents have COD concentrations of several hundred mg/l. Under certain conditions of discharge imposed to the effl uent, POM abatement is necessary. Elimination of pathogenic microorganisms , i.e., disinfection and inhibition of acute toxicity, is also required. Another class of toxic compounds, Micro-Pollutants (MPs), present in WWTP effl uents in much lower concentrations, μg/l even ng/l, has become a serious matter of concern. Ozonation, as a complementary stage in the treatment sequence of a WWTP, alone or in combination with biofi ltration, has been demonstrated by multiple laboratory-pilot tests and existing operating plants to be an effi cient and economically sound technology for the abatement of and POM and MPs and for disinfection. The purpose of this essay is to present ozone with its state-of-the-art features, from a qualitative as well as a quantitative aspect, with examples of modern applications for improved wastewater treatment.
The effects of combined ozonation and filtration on disinfection by-product formation
Water Research, 2005
The effects of combined ozonation and membrane filtration on the removal of the natural organic matter (NOM) and the formation of disinfection by-products (DBPs) were investigated. Ozonation/filtration resulted in a reduction of up to 50% in the dissolved organic carbon (DOC) concentration. Furthermore, humic substances were converted to nonhumic substances, with changes in the humic and non-humic substance concentrations of up to À50% and +20%, respectively. Ozonation/filtration resulted in the formation of partially oxidized compounds from NOM that were less reactive with chlorine, decreasing the concentration of simulated distribution system total trihalomethanes (SDS TTHMs) and simulated distribution system halo acetic acids (SDS HAAs) by up to 80% and 65%, respectively. Reducing the molecular weight cut-off (MWCO) of the membranes resulted in reductions in the concentrations of SDS TTHMs and SDS HAAs. Using a membrane with a 5 kD MWCO, the minimum gaseous ozone concentration required to bring about effective NOM degradation and meet regulatory requirements for chlorinated DBPs was 2.5 g/m 3 .