Intermediate Product Profile as a Result of Ozone Oxidation of Industrial Wastewater

The following were found when testing the wastewater in the study: 0.38% 7-Hydroxy-7-phenly-3,9-diisopropyl2,10-dioxadispiri, 1.71% 2-Propanone (CAS) Acetone, 20.87% 2-propanol, 2-methyl(CAS) tert-Butyl alcohol, 14.92% 2-Butanone (CAS) Methyl ethyl ketone, 62.11% Hydroperoxide, 1,1-dimethyl (CAS) Cadox TBH, COD (10,000-23,725 mg COD / l), total kjeldahl nitrogen (<6.2 mg / l), free chlorine (<0.05 mg / l) and chloride (> 9,042 mg / l). The water was then oxidated using ozone (4.1 g / h) and intermediate product formation and COD removal efficiency were studied. The current wastewater characteristics vary in line with product supply and demand.In this study, a cylinder reactor with an internal diameter of 5.8 cm and a height of 1.7 meters was used for ozonation (4.1 g/saat). After seven hours of ozonation, the wastewater pH value fell below four, showing that complex compounds were broken down to organic acids. At the end of the first, third, fourth, fifth and sixth hours of the ozonation process, respectively, nitrogen oxide (H), N, 2-Dimethydodecylamine (K), Propanoic acid, 2hydroxy-2-methyl (hydroxybutyric) (L), 2-Butanone, 3-hydroxy-3-methyl (M), 2,3 Butanedione (diacetyl) (N), Ammonium bicarbonate (O) ), Carbamicacid, monoammonium salt (Ammonium Carbamat) (P), Acetic acid, ethoxy-, 1-methylethyl ester (R) intermediates were formed. After seven hours of ozonation, the influent COD decreased from 17,000 mg / l to 2,860 mg / l. As a result of the ozone process, the organic substances were mostly transformed into 2-propanone (Acetone) (B) and 2-propanol, 2-methyl (tert-butyl alcohol) (C).


1.Introduction
In the treatment of industrial wastewater (containing high COD and low BOI), chemical oxidation methods and subsequent biological treatment systems are required. In the present study, industrial wastewater containing organic peroxide, high COD (higher than 10,000 mg/l), aldehyde, and ketone, which were difficult to break down, was analyzed.
Chemical oxidation is a widely used process for the treatment of water, including refractory compounds. Ozone is known to be a strong oxidant with the highest thermodynamic oxidation potential of common oxidants (Aparicio et al.,2007). As a chemical oxidation process, ozonation is a suitable system for decomposing pollutants and increasing the efficiency of biological treatments (Gomes et al.,2017). Ozone reacts quickly with electrophilic parts such as the chromophoric group of the azo bonds (N = N) ( De Souza et al., 2010). As ozone is a selective oxidation agent, the reactivity of different micro-pollutants with ozone is different (Hollender et al.,2009). Ozone is a strong oxidizing agent that breaks down compounds containing aromatic rings and double bonds. Thus, it can cause oxidative degradation of many organic compounds such as polyphenols. Depending on the pH value, the ozonation process follows two different paths. It is known that ozone oxidizes organic compounds by direct oxidation or by the production of hydroxyl radicals. Under acidic conditions, ozone reacts directly with organic compounds as an electrophile. Ozone attacks conjugated double bonds (Turhan et al.,2012). As a result, aldehydes, carboxylic acids and other by-products are formed (Asghar et al.,2015). Ozonation used in water and wastewater treatment results in the formation of various organic (carbonyl compounds) and inorganic by-products (Papageorgiou et al.,2017). Hydroxyl radicals are non-specific oxidizing agents that can degrade a number of contaminants because they react with almost all organic species. Reaction of molecular ozone with alkenes leads to the formation of an intermediate product, molozonide. The final products of this reaction are generally aldehydes, carboxylic acids, ketones and / or carbon dioxide (Gunukula et al.,2001). Reaction of ozone with hydrogen peroxide causes hydroxyl radical formation. This method has been successfully used in many applications. Since HO2is highly reactive with ozone, the decomposition rate of ozone in the presence of hydrogen peroxide increases with pH (Gunukula et al.,2001).
Ozone is applied to wastewater treatment as a strong oxidizer. It reacts selectively with organic compounds at acidic pH. Furthermore, ozone reacts slowly with certain organic substances such as inactivated aromatics or saturated carboxylic acids, and in most cases these organic compounds are not completely mineralized (Mehrjouei et al., 2015). Ozonation does not completely mineralize organic substances. Instead, it oxidizes them into more biodegradable forms (Lee et al.,2012). Ozonation is also a useful process in reducing toxicities in a wastewater stream. Pollutants such as phenols, cyanides, alcohols, pesticides, aldehydes and sulfides are successfully removed by ozonation (Gunukula et al.,2001). Ozone is a very strong oxidant that can react with a large number of chemicals (Eo = +2.07 V). As a result of the ozonation of some organic compounds, the biodegradability or toxicity of the oxidation products decreases (Gunukula et al.,2001).
After ozonation, an additional biological post-treatment is required to eliminate the negative ecotoxicological effects that occur during ozonation from biodegradable ozonation transformation products (OTPs) and oxidation by-products (OBPs) (Bourgin et al., 2018). The ozonation system alone cannot provide full mineralization. Therefore, a combination of ozonation and biodegradation has been proposed in a multistage system to improve cost and purification efficiency.
The main purpose of this research is to provide COD removal by oxidation with ozone of the wastewater of a factory producing organic peroxide and to reveal the formation and profile of the intermediate product. It has been determined that with ozone the organic matter has been transformed into the final oxidation products.

Materials and Method
In this study, COD exchange and intermediate product profile were examined as a result of ozonation of wastewater containing organic peroxide. The ozonation process was conducted with an ozone generator with a capacity of 4.1 g O3/hour. A stainless steel reactor with an internal diameter of 5.8 cm and a height of 1.7 m was used as the ozone reactor ( Figure 1). Unused ozone in the system was maintained in wash bottles containing potassium iodide. The raw wastewater composition was determined using the gas chromatography and mass spectrometry (Shimadzu GCMS-QP2020) ( Figure.1). During the seven-hour ozonation process, the product profile, pH and COD changes were observed. The ozone-treated wastewater was passed through the gas chromatography and mass spectrometry to determine the wastewater interim products and conversion rates. Figure 1 shows the experimental setup. The COD change interval ranges from 10,000 to 23,725 mg/l. The nitrogen concentration was generally low (<6.2 mg/l). Figure 1. Ozonation System (Sequential Batch) 0.38% 7-Hydroxy-7-phenly-3,9-diisopropyl-2,10-dioxadispirı, 1.71% 2-Propanone(CAS) Acetone, 20.87% 2-propanol,2-methyl-(CAS) tert-Butyl alcohol, 14.92% 2-Butanone(CAS) Methyl ethyl ketone, 62.11% Hydroperoxide,1,1-dimethyl(CAS). Cadox TBH parameters were measured in the wastewater samples taken from the balancing tank. In addition, the water contained 17,000 mg / l COD and very low total nitrogen (<6.2).
Intermediate product profile were determined by Shimadzu GCMS-QP2020. The ozonation was carried out for seven hours. Palintest interface photometer 7500(COD kit no:PL454, wtw cr2200 termoreactor) and WTW340 pH meter were used in the measurements of COD and pH. All measurements were performed according to standard methods (Standart Methods, 1995).

4.Conclusion
In this study, the oxidation of wastewater containing organic peroxide with ozone and the formation of intermediate product were investigated. Also, COD removal efficiencies were determined depending on the ozonation time. It