Impact Of Preozonation Research Articles

Enhanced organic matter degradation in shale gas wastewater treatment using Biofilm-Membrane bioreactors with varied filler Types, Pre-ozonation, and filler ratios

Membrane bioreactor (MBR) is a promising technology for the treatment of shale gas wastewater (SGW); however, there exists an urgent need for improvement in the degradation of organic matter. This study delves comprehensively into the impact of different filler types within a biofilm-membrane bioreactor (BF-MBR) for the treatment of SGW. Furthermore, the impact of pre-ozonation and filler ratios on the performance of BF-MBR is explored. Through the synergistic implementation of pre-ozonation and meticulously optimized filler ratios, a significant enhancement in removing dissolved organic carbon is achieved, notably reaching 36.0%-38.3% as opposed to the initial values of 14.4%-14.9%. Remarkably, groups subjected to pre-ozonized display membrane flux levels 42.2%-53.4% higher than non-pre-ozonated group. In the pre-ozonation phase, aerogel fillers (AF) demonstrate exceptional effectiveness. AF achieves the highest DOC removal (33.3%) and UV254 removal (70.6%). At the same time, AF group has a better effect of ameliorating membrane fouling. In addition, Pseudomonas and Constrictibacter are unveiled to be significantly correlated with the organic matter removal. In essence, this study provides practical insights that serve to optimize the treatment of SGW through the BF-MBR approach, effectively addressing its inherent challenges.

Impact of preozonation on biogas potential of PVC microplastics-containing waste sludge

<p>ABSTRACT Plastic pollution is increasing and plastic waste usually ends in environment. Microplastics (MP) as insoluble and anthropogenic micropollutant is ubiquitous and its concentration is expected to increase in the environment. One of important sources are wastewater treatment plants, where most of MP end in waste sludge. Promising technology for stabilization of waste sludge and reducing the volume and odor is anaerobic digestion, where anaerobic microorganisms digest organic matter and form biogas. The aim of this work was to evaluate inhibition on formed biogas and methane yield with and without ozonation of contaminated waste sludge with Polyvinylchloride (PVC). The inhibition of anaerobic microorganisms was determined by OxiTop® method, where biogas production was measured in terms of increased pressure (hPa). PVC increased biogas production up to 27% followed by increased CH4 production (up to 18%). Ozonation as a sludge pretreatment method, could inhibit or increase CH4 yield, depending on ozone dose (3.54 g h-1; lower dose or 3.99 g h-1; higher dose) and time of exposure to ozone (from 10 to 20 min). Higher dose of ozone with 10 minutes of ozonation, showed as the most efficient and improved biogas production up to 15% and CH4 production up to 14%.</p>

Impact of Pre-Ozonation during Nanofiltration of MBR Effluent.

This study aimed to investigate the impact of real MBR effluent pre-ozonation on nanofiltration performances. Nanofiltration experiments were separately run with non-ozonated real MBR effluent, ozonated real MBR effluent and synthetic ionic solution mimicking the ionic composition of the real MBR effluent. The specific UV absorbance and the chemical oxygen demand were monitored during ozonation of real effluent, and the mineralization rate was calculated through the quantitative analysis of dissolved organic carbon. The membrane structure was characterized using SEM on virgin and fouled membrane surfaces and after different cleaning steps. The results confirm the low effect of the ozonation process in terms of organic carbon mineralization. However, the chemical oxygen demand and the specific UV absorbance were decreased by 50% after ozonation, demonstrating the efficiency of ozonation in degrading a specific part of the organic matter fraction. A benefic effect of pre-ozonation was observed, as it limits both fouling and flux decrease. This study shows that the partial mineralization of dissolved and colloidal organic matter by ozonation could have a positive effect on inorganic scaling and decrease severe NF membrane fouling.

Controlling disinfection byproducts from treated wastewater using adsorption with granular activated carbon: Impact of pre-ozonation and pre-chlorination

This study measured chlorine- and chloramine-reactive precursors using formation potential (FP) tests of nine U.S. Environmental Protection Agency (EPA) regulated and 57 unregulated disinfection byproducts (DBPs) in tertiary-filtered wastewater before and after pilot-scale granular activated carbon (GAC) adsorption. Using breakthrough of precursor concentration and of concentration associated calculated cytotoxicity and genotoxicity (by correlating known lethal concentrations reported elsewhere), the performance of three parallel GAC treatment trains were compared against tertiary-filtered wastewater: ozone/GAC, chlorine/GAC, and GAC alone. Results show GAC alone was the primary process, versus ozone or chlorine alone, to remove the largest fraction of total chlorine- and chloramine-reactive DBP precursors and calculated cytotoxicity and genotoxicity potencies. GAC with pre-ozonation removed the most chlorine- and chloramine-reactive DBP precursors followed by GAC with pre-chlorination and lastly GAC without pre-treatment. GAC with pre-ozonation produced an effluent with cytotoxicity and genotoxicity of DBPs from FP that generally matched that of GAC without pre-oxidation; meanwhile removal of toxicity was greater by GAC with pre-chlorination. The cytotoxicity and genotoxicity of DBPs from FP tests did not scale with DBP concentration; for example, more than 90% of the calculated cytotoxicity resulted from 20% of the DBPs, principally from haloacetaldehydes, haloacetamides, and haloacetonitriles. The calculated cytotoxicity and genotoxicity from DBPs associated with FP-chloramination were at times higher than with FP-chlorination though the concentration of DBPs was five times higher with FP-chlorination. The removal of DBP precursors using GAC based treatment was at least as effective as removal of DOC (except for halonitromethanes for GAC without pre-oxidation and with pre-chlorination), indicating DOC can be used as an indicator for DBP precursor adsorption efficacy. However, the DOC was not a good surrogate for total cytotoxicity and genotoxicity breakthrough behavior, therefore, unregulated DBPs could have negative health implications that are disconnected from general water quality parameters, such as DOC, and regulated classes of DBPs. Instead, cytotoxicity and genotoxicity correlate with the concentration of specific classes of unregulated DBPs.

The impact of preozonation on the coagulation of cellular organic matter produced by Microcystis aeruginosa and its toxin degradation

Ozonation pretreatment is typically implemented to improve algal cell coagulation. However, knowledge on the effect of ozonation on the characteristics and coagulation of associated algal organic matter, particularly cellular organic matter (COM), which is extensively released during algal bloom decay, is limited. Hence, this study aimed to elucidate the impact of ozonation applied before the coagulation of dissolved COM from the cyanobacteria Microcystis aeruginosa. Additionally, the degradation of microcystins (MCs) naturally present in the COM matrix was investigated. A range of ozone doses (0.1–1.0 mg O3/mg of dissolved organic carbon – DOC) and ozonation pH values (pH 5, 7 and 9) were tested, while aluminium and ferric sulphate coagulants were used for subsequent coagulation. Despite negligible COM removal, ozonation itself eliminated MCs, and a lower ozone dose was required when performing ozonation at acidic or neutral pH (0.4 mg O3/mg DOC at pH 5 and 7 compared to 0.8 mg O3/mg DOC at pH 9). Enhanced MC degradation and a similar pattern of pH dependence were observed after preozonation-coagulation, whereas coagulation alone did not sufficiently remove MCs. In contrast to the benefits of MC depletion, preozonation using ≥ 0.4 mg O3/mg DOC decreased the coagulation efficiency (from 42%/48% to 28%–38%/41%–44% using Al/Fe-based coagulants), which was more severe with increasing ozone dosage. Coagulation was also influenced by the preozonation pH, where pH 9 caused the lowest reduction in COM removal. The results indicate that ozonation efficiently removes MCs, but its employment before COM coagulation is disputable due to the deterioration of coagulation.

Ultrafiltration and nanofiltration membrane fouling by natural organic matter: Mechanisms and mitigation by pre-ozonation and pH

The fouling of ultrafiltration (UF) and nanofiltration (NF) membranes during the treatment of surface waters continues to be of concern and the particular role of natural organic matter (NOM) requires further investigation. In this study the effect of pH and surface charge on membrane fouling during the treatment of samples of a representative surface water (Hyde Park recreational lake) were evaluated, together with the impact of pre-ozonation. While biopolymers in the surface water could be removed by the UF membrane, smaller molecular weight (MW) fractions of NOM were poorly removed, confirming the importance of membrane pore size. For NF membranes the removal of smaller MW fractions (800 Da–10 kDa) was less than expected from their pore size; however, nearly all of the hydrophobic, humic-type substances could be removed by the hydrophilic NF membranes for all MW distributions (greater than 90%). The results indicated the importance of the charge and hydrophilic nature of the NOM. Thus, the hydrophilic NF membrane could remove the hydrophobic organic matter, but not the hydrophilic substances. Increasing charge effects (more negative zeta potentials) with increasing solution pH were found to enhance organics removal and reduce fouling (flux decline), most likely through greater membrane surface repulsion. Pre-ozonation of the surface water increased the hydrophilic fraction and anionic charge of NOM and altered their size distributions. This resulted in a decreased fouling (less flux decline) for the UF and smaller pore NF, but a slight increase in fouling for the larger pore NF. The differences in the NF behavior are believed to relate to the relative sizes of ozonated organic fractions and the NF pores; a similar size of ozonated organic fractions and the NF pores causes significant membrane fouling.

Impact of Pre-Ozonation on Mechanical Properties of Selected Genotypes of Cucumber Fruits During the Souring Process

ABSTRACTCucumber souring is a process mediated by a microorganisms present on the surface of cucumber fruits. Sour pickles are fresh cucumbers that have been poured over with a sodium chloride solution and various types of spices. In the present research, pre-ozonated and control cucumber fruits were subjected to the souring processes. It was observed that ozone treatment had no negative impact on the quality of the fruit before the souring process. Moreover, sour pickles after pre-ozonation had better mechanic and sensory properties than the control.

Impact of preozonation on the bioactivity and biodiversity of subsequent biofilters under low temperature conditions—A pilot study

The combination of preozonation and subsequent biological granular activated carbon (O3/BAC) filtration is well known as a promising method for the removal of many pollutants. Temperature and nutrients are the dominant factors in external conditions to influence the biological communities. To explore the influence of preozonation under low temperature, the factors such as dissolved oxygen (DO), dissolved organic carbon (DOC) and NH 4 + -N were analyzed from the sampling ports every week; triphenyl tetrazolium chloride-dehydrogenase activity (TTC-DHA) and the nitrifying activity were detected along the bed height of biofilter at four levels (10, 40, 70 and 110 cm) on the 90th, 110th, and 130th day; microbial community, based on 16S rRNA gene-denaturing gradient gel electrophoresis (DGGE), was monitored on the 130th day of the operation. The observed microbial property showed that preozonation had a positive influence on bioactivity, biomass and nitrifying activity. Community analysis showed no significant difference on the biodiversity of nitrifying bacteria between the parallel filters in the inlet end based on the method employed. This result showed that biofilters’ performance is not correlated well with microbial biodiversity. The elevated functionality in O3/BAC filters can be a result of increased microbial activity, which was promoted by preozonation.

Impact of pre-ozonation on disinfection by-product formation and speciation from chlor(am)ination of algal organic matter of Microcystis aeruginosa

The increasing use of algal-impacted source waters is increasing concerns over exposure to disinfection byproducts (DBPs) in drinking water disinfection, due to the higher concentrations of DBP precursors in these waters. The impact of pre-ozonation on the formation and speciation of DBPs during subsequent chlorination and chloramination of algal organic matter (AOM), including extracellular organic matter (EOM) and intracellular organic matter (IOM), was investigated. During subsequent chlorination, ozonation pretreatment reduced the formation of haloacetonitriles from EOM, but increased the yields of trihalomethanes, dihaloacetic acid and trichloronitromethane from both EOM and IOM. While in chloramination, pre-ozonation remarkably enhanced the yields of several carbonaceous DBPs from IOM, and significantly minimized the nitrogenous DBP precursors. Also, the yield of 1,1-dichloro-2-propanone from IOM was decreased by 24.0% after pre-ozonation during chloramination. Both increases and decreases in the bromine substitution factors (BSF) of AOM were observed with ozone pretreatment at the low bromide level (50μg/L). However, pre-ozonation played little impact on the bromide substitution in DBPs at the high bromide level (500μg/L). This information was used to guide the design and practical operation of pre-ozonation in drinking water treatment plants using algae-rich waters.

The Trihalomethanes Formation Potential in Treated Waters Exposed to Ozone and Chlorine

The present study was implemented to investigate the trihalomethanes formation potential (THMFP) in drinking water treatment and to determine the impact of preozonation on the reduction of Trihalomethanes (THMs). The full-scale examination was carried out, using Luan River as the raw water. Two different preoxidation methods, prechlorination and preozonation were performed. THMFP and THM species were analyzed. The investigation indicated that 18.72% of THMFP was removed during preozonation. Further study on the distribution of THM species showed a significant reduction of Chloroform and bromodichloromethane, 20.62% and 17.39% during preozonation, respectively. The result suggested that the application of preozonation process is an effective method for reducing THMs generation in drinking water treatment. In the final effluent, the total removal rates of THMFP were 47.49% after preozonation and 55.67% after prechlorination.

Membrane fouling by vesicles and prevention through ozonation.

Membrane fouling is a major challenge in water and wastewater treatment. Recent observations that ozone mitigates membrane fouling during filtration of secondary effluent prompted this study into the impact of preozonation on membrane fouling caused by biogenic colloids. The focus of this study was on liposomes, synthetic vesicles composed of (phospho)lipid bilayers, which are representative of the diverse cellular vesicles present in all biologically impacted waters. The overarching hypothesis was that these biologically produced, nonrigid or "soft" colloids (e.g., vesicles) present in wastewater give rise to unique fouling behavior that can be mitigated by preozonation. Using dead-end ultrafiltration (UF) and batch ozonation tests, the key findings of this study were (1) liposomes fouled UF membranes faster (4-13 times membrane cake resistance (RC) per mgC filtered) than polysaccharides, fatty acids, and NOM on a DOC-normalized basis; (2) based on the estimated carbon distribution of secondary effluent, liposome-like biogenic nanomaterials could be responsible for 20-60% of fouling during UF; and (3) preozonation reduces liposomal fouling during UF, likely due to the disruption of the liposome structure through cleavage of the fatty acid tails at carbon-carbon double bonds.

Impact of preozonation on the performance of coagulated flocs

Ozone have been widely used as pre-oxidant before conventional water treatment processes, while some controversial results on the effects of preozonation on coagulation and particle stabilization, have been described. The performance of coagulated flocs can be substantially influenced by preozonation which can be ascribed to the variation of particles or organic substances in water. In order to elucidate the effects of preozonation as an aid in subsequent coagulation, the synthetic water composed of kaolin suspension and humic acid was coagulated after preozonation. The properties of floc, such as, size, fractal dimension and effective density, were investigated using laser light scattering analyzer and settling column measurement. It was found that the suspended particles had not been destabilized by preozonation as regarding the slight variation of zeta potential. As the ozone dose was less than 0.53 mg O 3 mg −1 C, floc size was not influenced apparently, while, as the ozone dose increased, the flocs were broken and the size decreased remarkably. Specifically, the fractal dimensions of flocs increased with increasing ozone dose, resulting in more densely packed flocs with low branch structure. Additionally, in terms of settling characteristics, the optimal pre-ozone dose was found to be 0.53 mg O 3 mg −1 C, which led to highest effective density of flocs with best liquid–solid separation efficiency.

The impact of preozonation and biodegradation on disinfection by-product formation

Ozonation and biological treatment were investigated as a means of controlling the formation of disinfection by-products (DBPs) as measured by total organic halides (TOX) and purgeable organic halides (POX). Organic matter from a groundwater and a river water source were used and chlorine or chloramines were used as the final disinfectant. The amount formed, the formation kinetics and the impact of disinfectant dose were investigated. Chloramination produced significantly less organic halides, especially POX, compared to chlorination. With both disinfectants and for both sources of organic matter, the nonpurgeable organic halide formation rate was found to be much faster than that of POX. Preozonation decreased the amount of organic halide formation by 10–40% upon subsequent chlorination. With chloramines preozonation had no significant impact on the extent of the reaction. Preozonation followed by biotreatment resulted in the least amount of organic halide formation with a reduction of 50–80% when chlorine was used, and greater than 90% with chloramines. In all cases examined, the ratio of organic halides to dissolved organic carbon decreased after biological treatment indicating a selectivity for the potential reactive sites. Based on the results of this bench scale study, pilot studies of biological treatment for DBP control are being made.

The Effect of Ozonation on the Removal of Organics by Coagulation – Flocculation

Abstract We present here some works which take place in the particular framework of the study of drinking water treatment of reservoir waters which contain high concentrations of organics, mainly humic substances. Previous studies on coagulation of fulvic acid solutions have proved that the optimal removal of organic matter was reached at acidic pH with 2 mg of ferricion per mg or organic carbon (summarized in this paper). The main question in this study is to know what is the impact of preozonation on the removal of organics by iron (III) coagulation. The study of the behavior of organics, in terms of UV-absorbance and TOC measurements was made on three aquatic fulvic acids and on two raw waters. The experiments carried out with fulvic acids showed that preozonation (at 0.5 mg O3/mg C) of fulvic acid appeared to have shifted the region of the optimal DOC removal towards the higher coagulant dose. Furthermore, increasing ozone doses led to a slight decreasing of coagulation efficiency at constant coagulan...

Impact of Prozonation on the Granulometric Distribution of Materials in Suspension

This study shows the impact of preozonation on the granulometric distribution of materials in suspension. Raw and ozonized waters have been analyzed bya laser granulometer. Analysis of the granulometric distribution of Seine river water has established that the suspended materials are constituted of four Gaussian populations and makes evident the codifications caused by the ozone on this granulometry as well ason the particulate organic carbon.

Ozonation: Its Effect on the Apparent Molecular Weight of Naturally Occurring Organics and Trihalomethane Production

Abstract Ozone pretreatment studies were conducted to evaluate the impact of preozonation on the apparent molecular weight distribution of naturally occurring organics and on the production of trihalomethanes following chlorination. The studies were carried out for eleven months to allow measurements of seasonal varations on the results of the preozonation process.