Effect of Ozone on Viability of Activated Sludge Detected by Oxygen Uptake Rate (OUR) and Adenosine-5′-triphosphate (ATP) Measurement

The current study focused on treatment of phenolic wastewater using an integrated process – dosing of ozone directly to activated sludge. The main goal was to analyze the effect of ozonation on viability of activated sludge in different systems – activated sludge in distilled water and activated sludge in wastewater. Two viability detection methods, oxygen uptake (OUR) rate and adenosine-5'-triphosphate measurement (ATP), were compared. The linear correlation between ATP and OUR measurements in studied range was found to be good (r² = 0.90). In case of ozonation of activated sludge in wastewater, ozone doses up to 42 mgO₃·gMLVSS^?1 did not influence the viability of sludge. In addition, contrary to ozonation of sludge in distilled water, soluble COD was reduced by 15.6% (at ozone dose of 42 mgO₃·gMLVSS^?1).     

Ozonation of activated sludge in the recycle stream

Intermittent ozonation of a part of the recycle sludge was performed two times a week for a laboratory‐scale reactor at an average ozone dose of 0.019 g O₃(gSS_ozonated)^?1. Under these conditions a decrease of about 50% in sludge growth was obtained for the ozone‐treated system, in comparison with the control. As a consequence less sludge had to be removed from the test reactor. Only a slight decrease in quality of effluent was noticed. A comparative cost calculation was made, based on these results, between an ozone‐treated activated sludge system and a traditional activated sludge system. © 2001 Society of Chemical Industry     

影响臭氧化污泥减量工艺的因子

采用臭氧作为剩余污泥的细胞裂解剂,并与淹没式生物膜工艺相结合进行污泥减量的实验研究,臭氧化后的污泥上清液回流入曝气池与污水合并处理。结果表明:在每kgMLSS臭氧投量为0.05 kg,臭氧化污泥体积流量为进水量的5%条件下,淹没式生物膜系统对SCOD和NH3-N的平均去除率分别为87.06%和84.80%,出水水质同对比实验相当;同时获得了去除1 g SCOD得到0.054 gMLSS的剩余污泥产率,与对比实验相比降低了78.4%。     

Purification of Phenolic Wastewater Using Aerobic Bio-oxidation Combined with Activated Carbon Treatment and Ozonation

The combined process – aerobic bio-oxidation with activated carbon addition and ozonation was studied (ABO/AC/O3). The performance of the process was compared with conventional aerobic bio-oxidation (ABO). The studies were carried out in two continuous and periodic reactors to evaluate the purification efficiencies (in terms of COD, BOD and resorcinols removal), excess sludge generation and stability of the bioreactors against shock loadings. The parameters in continuous combined process were as follows: organics loading was 620 mgCOD/(day·L), activated carbon concentration 1g/L and ozone dose 2.45 mgO₃/L (mg ozone per liter of treated water). In periodic reactors the combined process was studied at lower activated carbon concentration and ozone dose (0.3 g/L and 0.57 mg/L respectively).

The results indicated that compared with conventional ABO, the co-effect of AC addition and short-termed (less than 1 week) or intermittent ozonation improved the removal of COD and BOD, while the longer period of ozonation resulted in reduction of excess sludge concentration in the bioreactor. The impact of AC and ozone on the ABO in the combined process did not concern only increased biomass activity, but AC and ozone improved also settleability of activated sludge and enhanced stability of the bioreactor to shock loadings.     

Ozone treatment of textile effluents and dyes: effect of applied ozone dose,pH and dye concentration

The ozonation of wastewater supplied from a treatment plant (Samples A and B) and dye‐bath effluent (Sample C) from a dyeing and finishing mill and acid dye solutions in a semi‐batch reactor has been examined to explore the impact of ozone dose, pH, and initial dye concentration. Results revealed that the apparent rate constants were raised with increases in applied ozone dose and pH, and decreases in initial dye concentration. While the color removal efficiencies of both wastewater Samples A and C for 15 min ozonation at high ozone dosage were 95 and 97%, respectively, these were 81 and 87%, respectively at low ozone dosage. The chemical oxygen demand (COD) and dissolved organic carbon (DOC) removal efficiencies at several ozone dose applications for a 15 min ozonation time were in the ranges of 15–46% and 10–20%, respectively for Sample A and 15–33% and 9–19% respectively for Sample C. Ozone consumption per unit color, COD and DOC removal at any time was found to be almost the same while the applied ozone dose was different. Ozonation could improve the BOD₅ (biological oxygen demand) COD ratio of Sample A by 1.6 times with 300 mg dm^?3 ozone consumption. Ozonation of acid dyes was a pseudo‐first order reaction with respect to dye. Increases in dye concentration increased specific ozone consumption. Specific ozone consumption for Acid Red 183 (AR‐183) dye solution with a concentration of 50 mg dm^?3 rose from 0.32 to 0.72 mg‐O₃ per mg dye decomposed as the dye concentration was increased to 500 mg dm^?3. © 2002 Society of Chemical Industry     

Application of Ozone Involving Advanced Oxidation Processes to Remove Some Pharmaceutical Compounds from Urban Wastewaters

Different UVA radiation and advanced oxidation systems, most of them involving ozone, have been applied to remove mixtures of three contaminants of pharmaceutical type: diclofenac (DCF), sulfamethoxazole (SMT) and caffeine (CFF), both in ultrapure and secondary treated wastewater. The influence of the water matrix has been studied in terms of individual compound concentration and TOC removal. Also, biodegradability of the treated wastewater before and after the advanced oxidation process, as BOD/COD ratio, the partial oxidation yield, the increment of average state of carbon oxidation and ozone consumption have been determined. For mgL^?1 to 100 μgL^?1 concentrations and regardless of the ozone process and water type, DCF and SMT are removed in less than 10 min mainly by direct reaction with ozone, especially in the case of DCF. CFF, on the contrary, is mainly removed through hydroxyl radicals. For lower concentration (≤100 μgL^?1), DCF still disappears by direct ozonation, CFF by hydroxyl radicals oxidation and SMT through both direct ozonation and hydroxyl radical oxidation. Once DCF and SMT have disappeared, TOC is removed by reacting with hydroxyl radicals, regardless of the water matrix. Photocatalytic ozonation allows the highest TOC degradation rate, partial oxidation yield, increment of average state of carbon oxidation and biodegradability together to the lowest ozone consumption per mg TOC eliminated.     

Enhancing Biodegradability of Textile Wastewater by Ozonation Processes: Optimization with Response Surface Methodology

ABSTRACT

In this study, an ozonation process was used to increase biodegradability of textile wastewater by considering chemical oxygen demand (COD) and color removal. Response surface methodology was applied in order to determine the significance of independent variables which are initial pH, reaction time and ozone dose. While a biological oxygen demand (BOD)/COD rate of 0.315 was obtained at optimum conditions, which are pH 9, 75 min of reaction time and 26 mg/L ozone dose, color and COD removal was obtained at 74% and 39%, respectively. BOD/COD ratio value increased from 0.18 to 0.32 by ozonation process. In addition, k coefficient for BOD also increased from 0.21 to 0.30 d^?1.     

Ozonation of NSAID: A Biodegradability and Toxicity Study

This work deals with the biodegradability and toxicity of three non-steroidal anti-inflammatory drugs (NSAID) (diclofenac, ibuprofen and naproxen) treated by ozonation. The results show that the total removal of 200 mg L^?1 of diclofenac and 100 mg L^?1 of naproxen is possible using an ozone dose of 0.20 and 0.04 g L^?1, respectively. For 200 mg L^?1 of ibuprofen, 90% removal is achieved using an ozone dose of 2.3 g L^?1. The BOD₅/COD ratio, the Zahn-Wallens test and EC₅₀ toxicity test (Microtox) are chosen as biological and toxicity indicators of NSAID intermediates. The evolution of BOD₅/COD ratio during 1 hour of treatment is evaluated and the results show that ozonation improves the biodegradability for the three NSAID treated solution. The Zahn-Wellens test for diclofenac and ibuprofen solutions shows that biological mineralization, after 28 days, is higher for diclofenac than for ibuprofen solution. According to the Microtox test, the treatment with ozone removes the toxicity of the naproxen solution. Taking into account the results obtained with the biocompatibility tests it could be assumed that ozonation is an adequate treatment for removal NSAID in aquatic medium, and the ozonated effluents could be post-treated in a biological wastewater facility.     

The Optimization of Ozonation and Biological Activated Carbon (BAC) in a Water Reclamation Context

A pilot plant study showed that an ozone dosage of about 4 mg/l before filtration and BAC led to the most cost-effective COD removal in the reclamation of water from activated sludge effluent. The combination in the reclamation of water from activated sludge effluent. The combination of ozonation, filtration and BAC could maintain a least COD removal fraction of 30 per cent for more than three times as long an inter–reactivation period as for filtration and BAC without ozonation. Filtration has not been found to contribute significantly to the COD removal by the above combination of process units.     

Enhancing the ozonation of industrial wastewater with electrochemically generated copper(II) ions

This study evaluates the effect of adding electrochemical copper(II) ions into an ozonation process for treating industrial wastewater. Combining the processes resulted in a synergy that enhanced the reduction of physicochemical parameters (COD, TOC, color, turbidity, Z-Potential, and conductivity). In only 15 minutes the integrated process reduced the COD by 83%, TOC by 78 %, color by 93%, turbidity by 77%, and conductivity by 27% at relatively low current density (12.5 mA cm^?2). Thus, the combination of the electrochemical and ozonation processes noticeably improves wastewater quality, decreases the process time, and reduces the sludge production.     

The use of 3,3′,4′,5‐tetrachlorosalicylanilide as a chemical uncoupler to reduce activated sludge yield

To determine whether chemical additions can be used to reduce sludge production in biological wastewater treatment, 3,3′,4′,5‐tetrachlorosalicylanilide (TCS) was added to activated sludge cultures as a metabolic uncoupler. Batch tests confirmed that TCS is an effective chemical uncoupler in reducing the sludge yield at concentrations greater than 1.0 mg dm^?3; a TCS concentration of 1.0 mg dm^?3 reduced sludge yield by approximately 50%. Substrate removal capability and effluent nitrogen concentration were not affected adversely by the presence of TCS when dosed every other day in a range of 2.0–3.6 mg dm^?3 during the 40‐day operation of activated sludge batch cultures. Such sludge growth reduction was associated with the enhancement of microbial activities in terms of the specific oxygen uptake rate and dehydrogenase activity. Sludge settleability of the treated and control samples was qualitatively comparable and not significantly different. Filamentous bacteria continued to grow in sludge flocs only in the control reactor at the end of the 40‐day trial. These results suggest that TCS treatment of activated sludge systems may reduce excess sludge yield. Copyright © 2003 Society of Chemical Industry     

The Study on the Ceramic Membrane Wastewater Reuse System with Pre-Ozonation and Coagulation

A new wastewater reuse system using ozonation, coagulation and MF ceramic membrane (0.1 μm) filtration was developed. The testing was performed using secondary effluent treated at the wastewater treatment plant (WWTP) in Tokyo, Japan. The volume of treated water by the pilot study equipment is about 90 m³/day. The combination of pre-ozonation and coagulation processes achieves continuous stable membrane filtration with flux of 4m³/m²/day (167 LMH). A stable membrane filtration could be maintained by controlling ozone dosing rate depending on secondary effluent (raw water) quality fluctuation. The COD (Mn) removal ratio in raw water was 50 to 60%, and the color removal ratio satisfied 80% or higher. The quality of the treated water that was obtained from our pilot study was better than the California's standards.     

Systematic Analysis of the Biochemical Characteristics of Activated Sludge During Ozonation for Lowering of Biomass Production

Properties of activated sludge during ozonation were analyzed. The structure and surface characteristics altered with the increase of ozone dosage. At low ozone dosage, the floc structure was completely dismantled. Floc fragments reformed through reflocculation at an ozone dosage greater than 0.20 g O₃·g^?1 mixed liquor suspended solids (MLSS). Inactivation of microorganisms in the activated sludge mixture was caused by ozonation. Microbial growth decreased by up to 65% compared to the control. Simultaneously, 92.5% of nucleotide and 97.4% of protein in microbial cells of the sludge were released. Organic substance, nitrogen and phosphorus were released from the sludge during the ozonation process. The initial value of soluble chemical oxygen demand (SCOD) was 72 mg·L^?1. When the ozone dosage was 0.12 g O₃·g^?1 MLSS, the value of SCOD rapidly reached 925 mg·L^?1, increased by almost 12-fold. Simultaneously, 54.7% of MLSS was reduced. The composition of MLSS was changed, indicating that the inner water of cells and volatile organic substance decreased during the ozonation process.     

Disinfection of recycled red‐meat‐processing wastewater by ozone

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 Escherichia coli 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     

污泥臭氧减量对淹没式生物膜工艺运行效能的影响

针对淹没生物膜法(SBF)和污泥臭氧化各自在污泥减量方面的优点,提出了化学臭氧化和复合生物膜法相结合的污泥减量工艺,并对臭氧化对SBF运行效能的影响进行了实验研究。通过2个并行的SBF系统污泥臭氧化结果进行对比,结果显示臭氧化能够显著降低系统的污泥产率(0.043 kg/kg,较不加臭氧化的SBF系统下降了76%),同时不对硝化和有机物的去除作用产生明显的影响,系统出水水质良好。     

Degradation of Carbamazepine by Photo-assisted Ozonation: Influence of Wavelength and Intensity of Radiation

This article presents the results of an investigation into the function of UV in a photo-assisted ozonation process for treatment of carbamazepine (CBZ) in treated domestic wastewaters. Experiments were conducted on synthetic spiked water and secondary treated municipal wastewater. Degradation of CBZ was studied for various combination of O₃ dosage ranging from 4.8 to 14.4 mg/h and UV intensities with varying intensity and wavelength (UVC: λ = 254 nm and UVA: 352 nm). In synthetic spiked water, CBZ was degraded to below detectable limits within 0.5 min for ozone dose of 14.4 mg/h. The rate of degradation of CBZ increased exponentially with increase in ozone dose following a zero-order rate at each dose level. The degradation rate of CBZ in wastewater was slower compared to deionized water (DI) water by 40–75% for various doses of ozone, presumably due to the presence of organic matter remaining in treated wastewater. Optimal UV intensities for UVA and UVC were obtained as 0.62 and 0.82 mW/cm² for all doses of ozone in synthetic spiked water samples and UV intensities beyond this resulted in lower rates of degradation of CBZ. For photo-assisted ozonation with ozone doses of 9.6 and 14.4 mg/L, rate constants were two times higher for UVA irradiations as compared to UVC irradiation. Contrary to observations in DI water, experiments in wastewater showed increase in rate of degradation with higher UV intensities. Overall, photo-assisted ozonation was found to be appropriate for both water and wastewater treatment by exploiting the benefit of direct attack of ozone and of produced ^?OH radicals to yield a greater extent of mineralization of CBZ.     

臭氧氧化法深度处理造纸废水试验研究

首先采用复合混凝剂对造纸废水二级出水进行了预处理,再用臭氧进行氧化处理.研究了在不同臭氧量、pH条件下,臭氧氧化法对造纸废水中COD和色度的去除效果,及不同臭氧产生速率和反应时间对COD与色度的去除效果,分析了臭氧氧化污染物的机理.结果表明,臭氧氧化效果随臭氧量、反应时间的增加而增强,但增强幅度越来越小;臭氧投加速率为13.98 mg/min、停留时间为30 min时,COD和色度去除率分别可达62-3%和99.5%,去除效果明显.     

臭氧预氧化强化煤气废水生化处理研究

煤气废水生物处理出水存在着色度、NH3-N和COD等指标超标的问题,需要进行深度处理。臭氧氧化是一种比较常用的深度处理方法,然而单独依靠臭氧氧化去除废水中的COD和NH3-N需要较高的臭氧投加量,处理成本很高。探讨了臭氧对煤气废水生物处理出水的预氧化效果及其对后续生物处理过程的强化作用。实验表明,臭氧对废水的色度去除很有效,投加<160mg/L的臭氧就可去除90%的色度,废水pH较低时色度去除效果较好;臭氧氧化对废水残留COD有一定的去除作用,不同的pH条件下去除率有差异,总体每mg臭氧可去除0.44～0.64mg的COD;臭氧有效投加质量浓度为240mg/L时,废水COD去除率降低,氧化后出水BOD上升,有利于后续生物处理;臭氧氧化对废水NH3-N的去除效果不明显。对比原水与臭氧氧化出水的分子质量分布特征,发现废水经臭氧氧化后其成分有两种变化趋势,既有一定量的小分子物质产生,又有大分子物质聚合生成,因此臭氧预氧化后续处理工艺应以生物处理为主,同时配合混凝处理工艺。     

Promoting Hydroxyl Radical Production during Ozonation of Municipal Wastewater

Hydroxyl radical (HO^?) production during ozonation of municipal wastewater was investigated with and without liquid or solid-phase promoters. For liquid-phase promoters, an “ozone dose threshold” was observed, below which addition of H₂O₂ yielded no discernible increase in the rate of HO^? production. This threshold occurs because ozonation of bulk organics in wastewater promotes HO^? due to the presence of ambient promoters. Although solid-phase catalysts are reported to promote oxidation of contaminants, ozonation of effluent over TiO₂ or GAC was no more effective on trace organic removal than over inert surfaces.     

Effect of stream segregation on ozonation for the removal of significant COD fractions from textile wastewater

Ozonation was tested on selected streams of cotton finishing textile plant wastewater for optimizing chemical oxygen demand (COD) removal. For this purpose, significant COD fractions in the wastewater were experimentally identified and the effect of ozone on these fractions was investigated. Ozonation experiments were performed with a 1 dm³ sample volume. Ozone treatment of batches of raw wastewater provided, at a rate of 62 mg min^?1 and a gas feeding time of 15 min, achieved complete colour removal but only 21% COD reduction. Increasing the feeding time to 30 min slightly increased the COD removal to 32%. At this feeding time, removal of the readily biodegradable COD was 60%, but soluble inert COD reduction remained at 16%, indicating selective preference of ozone for simpler compounds. At low concentrations, ozone was mainly influential on soluble COD compounds. Longer feeding times also affected particulate compounds, resulting in the solubilization of the COD fractions. Pre‐ozonation of the dye‐house wastewater, as a segregated stream, proved much more effective in the breakdown of refractory organic compounds, rendering the overall plant effluent more amenable to biological treatment. © 2002 Society of Chemical Industry