Oxi-Bioremediation of Hazardous Biosludge from Integrated Pulp and Paper Mill

The present study establishes the feasibility of decomposition of hazardous biosludge from an integrated pulp and paper mill with ozone and subsequent biodegradation of disintegrated biomass in the activated sludge process (ASP). The 16.0 ± 0.5% solubization of mixed liquor volatile suspended solids and 22.6 ± 2.3% dechlorination of AOX compounds of biosludge were observed at an ozone dosage of 43–47 mg O₃/g dry solid. More than 90% PCDD and PCDF compounds were degraded. The recycling of disintegrated sludge to ASP did not affect the performance of the process in terms of reduction in total organic carbon, CODs, color and AOX. The proliferation of filamentous organisms was controlled by ozone treatment of sludge. The biomass yield was only 0.06 g with ozone treatment, whereas the same was 0.31 g/g of CODs removal in control reactor.     

Degradation and Transformation of Organic Compounds in Songhua River Water by Catalytic Ozonation in the Presence of TiO2/Zeolite

This paper presents experimental results of the catalytic ozonation of Songhua River water in the presence of nano-TiO₂ supported on Zeolite. The removal efficiency of TOC and UV₂₅₄, the variation of AOC and molecular weight distribution of organics was studied. Results showed that TOC and UV₂₅₄ removal efficiency by ozone was improved in the presence of TiO₂/Zeolite, and increased by 20% and 25%, respectively. The part of organic compounds less than 1000 Da increased in ozonation, but decreased in catalytic ozonation. The AOC of water increased in catalytic ozonation, and the increase of AOC was particularly obvious when ozone dose increased from 28.8 mg·L^?1 to 46.6 mg·L^?1. The degradation and transformation of organic compounds was analyzed by means of GC-MS. The total number of organic compounds was reduced from 50 in the untreated water to 36 and 20, respectively, in ozonation and catalytic ozonation. The removal efficiency of the total organic compounds peak area in ozonation and catalytic ozonation were 23.5% and 62.5%, respectively. Most of the hydrocarbons could be removed easily in ozonation and catalytic ozonation. The organic compounds having hydroxyl, carboxyl or carbonyl groups were hard to be removed in ozonation, but could be removed efficiently in the presence of TiO₂/Zeolite.     

Sludge Ozonation and its Application to a New Advanced Wastewater Treatment Process with Sludge Disintegration

The applicability of sludge ozonation on wastewater treatment processes was investigated to reduce the amount of excess sludge without losing phosphorus removal efficiency. Solubilization degree per ozone consumption for general sludge was in the range from 2.4 to 5.8 gSS/O₃ and from 4.1 to 7.7 gCOD/gO₃. Around 80 to 90% of solubilized organics was biodegradable at a solubilization degree of 0.3. Based on the experimental results, a lab-scale plant with sludge ozonation and phosphorus crystallization was constructed to investigate the treatment performance. Amount of excess sludge was reduced by 93% with almost complete removal of soluble BOD and phosphorus removal efficiency of more than 80%. The percentage of the effluent COD_Cr discharge increased from 10% to 14–17% after installing ozonation and crystallization because of the formation of non-biodegradable organic substances in ozonation process. Energy consumption of the innovative advanced process is comparable or can be even smaller than that of the conventional anaerobic/oxic (A/O) process in spite of the installation of ozonation and crystallization.     

Effect of Ozonation on Biodegradability Characteristics of Surplus Activated Sludge

The study investigates the effect of sludge ozonation on solid matter species, disintegration properties, sludge components, and solubilization characteristics under different operating conditions. Ozonation of surplus activated sludge samples taken from the secondary settling tank of a domestic wastewater treatment plant indicates that soluble nitrogen, phosphorus and COD concentrations proliferate as a consequence of extending the ozone feeding time. A steady increase both in soluble nitrogen concentration and ratio of organic phosphorus to soluble phosphorus is observed through ozonation where specific ozone doses range between 4 and 11 mg O₃/g SS. Combined treatment of chemical oxidation and aerobic biodegradation to surplus activated sludge is also applied to improve the biodegradability of organic matter by partial chemical oxidative pretreatment with as little specific ozone consumption as possible. The partial oxidation by integrated ozonation is operated as a pre-oxidation step for the subsequent biological degradation, due to the fact that the competition with biological degradation in removing biodegradable organic compounds is avoided and most probably a more biodegradable sludge composition is obtained by means of ozonation. Combined treatment of chemical oxidation and aerobic biodegradation conducted to scrutinize the synergic effect of the coupled treatment system reveals that TS and COD removal efficiencies of ozonated sludge samples cannot be improved beyond the third aerobic biodegradation step.     

Ozonation of Primary Sludge and Digested Sludge to Increase Methane Production in a Chemically Enhanced Primary Treatment Facility

The purpose of this research was the investigation of the ozonation of sludge as a method to improve anaerobic digestion performance in a chemically enhanced primary treatment facility. Batch tests were conducted to evaluate the effect of ozonation on the physicochemical characteristics of both primary and digested sludge. Then, the performance of semi-continuous anaerobic digesters in combination with ozone treatment was investigated (pre-ozonation and post-ozonation). Ozonation of primary sludge did not increase the soluble COD nor the biodegradable COD, but resulted in the mineralization of a fraction of the organic matter into CO₂. However, the ozonation of anaerobic digested sludge resulted in an increase in soluble COD and biodegradable COD and in a small level of mineralization at the dose of 90 mg O₃/g COD. Pre-ozonation of primary sludge was not effective in enhancing the performance of the anaerobic digester. The coupling of ozonation and anaerobic digestion by means of the post-ozonation of digested sludge was found to be effective in improving methane production (+16%), for COD removal efficiency and for the dewaterability of anaerobic digesters compared to the control digester.     

Activated sludge process coupled with intermittent ozonation for sludge yield reduction and effluent water quality control

BACKGROUND: Ozone is applied in wastewater treatment for effluent water quality improvement (post‐ozonation) as well as for excess sludge reduction (in the recirculation line). There is some evidence that ozone dosed directly to aerobic biooxidation (ABO) process enhances degradation of recalcitrant compounds into intermediates, following their biodegradation in the same reactor. However, no information regarding the influence of ozone on sludge yield in this system was found. Therefore, the current work aimed to evaluate the effect of ozone on the sludge yield when ozone is dosed directly to the ABO process. In addition, batch and continuous treatment schemes for phenolic wastewater treatment are compared. RESULTS: The results revealed that an optimal ozone dose of ～30 mgO₃ L^?1 day^?1 reduced the sludge yield by ～50%, while effluent water quality in terms of total chemical oxygen demand (TCOD), compared with a conventional ABO process, was improved by 35.5 ± 3.6%. Slight improvement in soluble COD removal at the same ozone dose was also detected. The toxicity of effluent water was reduced as the ozone dose was increased. CONCLUSIONS: In an integrated ozonation‐ABO process it is possible to simultaneously reduce sludge yield and to improve effluent water quality, as COD and toxicity are reduced. Copyright © 2011 Society of Chemical Industry     

Performance evaluation of ozonation and an ozone/hydrogen peroxide process toward development of a new sewage treatment process—Focusing on organic compounds and emerging contaminants

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-O₃/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.     

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.     

Single and Combined Application of Ozonation and Coagulation/Flocculation for Humic Acid Removal

Humic acids are often found in surface and ground waters as a result of organic matter decay. In this study, water samples containing 50 mgL^?1 humic acid were treated by conventional application of coagulation/flocculation technique. The results showed 70% ±10 turbidity, ≥82% ±10 UV₂₅₄ absorbance and 85% ±10 total organic carbon removal under pH 5–9 and above 5 mgL^?1 Fe³⁺ coagulant doses. Application of post-ozonation significantly increased the UV₂₅₄ absorbance and turbidity removal under low dose Fe³⁺ application. On the other hand ozonation prior to coagulation/flocculation process altered the structure of HA and caused no significant improvement in removal efficiencies.     

Distribution and Removal of Polycyclic Aromatic Hydrocarbons in Two Italian Municipal Wastewater Treatment Plants in 2011–2013

PAH (Polycyclic Aromatic Hydrocarbons) analyses were carried out on samples from two Wastewater Treatment Plants (WWTPs) in Lombardy, similar for treatment sequences but fed on different influents: industrial component accounts for 70% at Alto Seveso plant while it is absent in Nosedo plant. Sampling concerned the influent and the effluent from activated sludge reactor and the final effluent after disinfection (ozonation for Alto Seveso and peracetic acid treatment for Nosedo). The concentrations of total PAHs were 5.3 ± 4.0 μg L^?1 and 2.4 ± 1.3 μg L^?1 in Alto Seveso and Nosedo influent, respectively. The lowest molecular weight PAHs had the highest concentrations in both plants; acenaphthene and naphthalene were the most important components in the influent to Alto Seveso and Nosedo WWTPs, respectively. The higher molecular weight compounds had the lowest concentrations and benzo(g,h,i)perylene and dibenzo(a,h)anthracene were never detected. Most of the PAH load entered biological treatment in dissolved form. For both plants PAHs were mostly removed in the biological section (96.5% and 89.5% for Alto Seveso and Nosedo, respectively), while disinfection had a minor role. Peracetic acid (Nosedo) seemed more efficient than ozone (Alto Seveso) in the removal of PAHs (4.18% and 0.89%, respectively). It is now necessary to confirm this result by using the same effluent for the two disinfection treatments.     

Effect of Ozone on Removal of Dissolved Organic Matter and its Biodegradability and Adsorbability in Biotreated Textile Effluents

A study was conducted on the efficacy of ozonation in removing dissolved organic matter (DOM) in biotreated textile effluents and effects on its biodegradability and adsorbability. Results showed the efficient removal of color and fluorescence compounds were achieved through ozonation, due to increasing hydrophilicity and lowering molecular weight of DOM. A significant biodegradability improvement was also observed, and DOM adsorbability on activated carbon was highly dependent on ozone dosage. As the key parameter, consumed 3.8 g O₃/?g TOC₀ was the optimal dosage in the hybrid process combining ozonation with biological activated carbon (BAC) for wastewater reclamation.     

Removal Characteristics of Organic Pollutants in Sewage Treatment by a Pre-Coagulation,Ozonation and Ozone/Hydrogen Peroxide Process

The applicability of a sequential process of ozonation and ozone/hydrogen peroxide process for the removal of soluble organic compounds from a pre-coagulated municipal sewage was examined. 6–25% of initial T-COD_Cr was removed at the early stage of ozonation before the ratio of consumed ozone to removed T-COD_Cr dramatically increased. Until dissolved ozone was detected, 0.3 mgO₃/mgTOC₀ (Initial TOC) of ozone was consumed. When an ozone/hydrogen peroxide process was applied, additional COD_Cr was removed. And we elucidated that two following findings are important for the better performance of ozone/hydrogen peroxide process; those are to remove readily reactive organic compounds with ozone before the application of ozone/hydrogen peroxide process and to avoid the excess addition of hydrogen peroxide. Based on these two findings, we proposed a sequential process of ozonation and multi-stage ozone/hydrogen peroxide process and the appropriate addition of hydrogen peroxide. T-COD_Cr, TOC and ATU-BOD₅ were reduced to less than 7 mg/L, 6 mgC/L and 5 mg/L, respectively after total treatment time of 79 min. Furthermore, we discussed the transformation of organic compounds and the removal of organic compounds. The removal amount of COD_Cr and UV₂₅₄ had good linear relationship until the removal amounts of COD_Cr and UV₂₅₄ were 30 mg/L and 0.11 cm^?1, respectively. Therefore UV₂₅₄ would be useful for an indicator for COD_Cr removal at the beginning of the treatment. The accumulation of carboxylic acids (formic acid, acetic acid and oxalic acid) was observed. The ratio of carbon concentration of carboxylic acids to TOC remaining was getting higher and reached around 0.5 finally. Removal of TOC was observed with the accumulation of carboxylic acids. When unknown organic compounds (organic compounds except for carboxylic acids) were oxidized, 70% was apparently removed as carbon dioxide and 30% was accumulated as carboxylic acids. A portion of biodegradable organic compounds to whole organic compounds was enhanced as shown by the increase ratio of BOD/COD_Cr.     

造纸废水处理工艺的应用

论述了造纸厂废水不同的处理工艺及其特点.对比了各种不同的处理工艺得到以下结论:厌氧和好氧工艺的结合能有效去除可溶性可生物降解的有机污染物;通过真菌处理、絮凝、化学法、臭氧处理可以有效去除色度等;通过吸附、臭氧处理和膜过滤技术可有效去除含氯酚类有机物以及可溶性有机卤化物等.     

Effects of Ozonation on Molecular Weight Distribution of Humic Substances and Coagulation Processes – A Case Study: The Úzquiza Reservoir Water

In this article the influence of preozonation on the effectiveness of NOM removal via coagulation processes will be studied (focusing on the influence of the calcium hardness) as well as changes in MW (molecular weight) distribution of humic substances caused by ozonation. Additionally, THMFP removal in both ozonation and preozonation-coagulation processes is assessed. Three different types of water have been used in this study: a natural water from the Úzquiza Reservoir (Burgos, Spain), a synthetic water prepared using natural fulvic acids extracted from the Úzquiza Reservoir and a synthetic water prepared using a commercially supplied humic acid. Molecular weights of humic substances were determined using high-performance size exclusion chromatography (HPSEC); average molecular weights calculated for the unozonated humic substances are 4500 Da for the commercial humic acids and 1000 Da for the natural fulvic acids extracted from the Úzquiza Reservoir. Preozonation shifted the molecular weight distribution of humic substances (both humic and fulvic acids) towards lower average molecular weight values. For the natural water from the Úzquiza Reservoir (with low levels of calcium hardness and hydrophobic fraction (humic substances) being the main fraction of NOM), preozonation has a negative effect on the effectiveness of the coagulation process for NOM removal: the percentages of TOC removal via coagulation decrease with increasing ozone dosage; the maximum TOC removal (33%) is achieved for the unozonated water. Also for this water, ozonation reduced 5–25% of THMFP with ozone doses varying from 0.25 to 2.5 mg O₃/L. A preferential THMFP removal, that is to say, higher reduction in THMFP (43%) relative to TOC (28%) is achieved by the coagulation-flocculation process; this also occurs when preozonation is used, independently of ozone dosage.     

Improvement of Biodegradability of Oil Field Drilling Wastewater Using Ozone

The possibility of improving the biodegradability of drilling wastewater using ozone was investigated following coagulation pretreatment. The biodegradability of wastewater was improved significantly following the start of ozonation, and the molecular weight of organic compounds decreased continuously with the progress of oxidation. It is interesting that minimum biochemical oxygen demand, total organic carbon (BOD/TOC) ratio (0.4 g/g) was observed when wastewater was treated with ozone continuously for 15 min. The combination of ozonation for 5 min (ozone consumption ratio of 2.6 g ozone/g TOC) followed by biological degradation produced a total TOC removal rate of 54.3%, which was comparable to direct ozonation for 30 min under the same conditions (TOC removal rate of 54.9%; ozone consumption ratio of 8.7 g ozone/g TOC). It is clear that biological treatment following short-term ozonation was very efficient in TOC removal. A process of successive coagulation-precipitation, ozone oxidation, and biodegradation seemed to be a good option for drilling wastewater treatment.     

Photocatalytic ozonation of gallic acid in water

Aqueous solutions of gallic acid have been treated with five different oxidation‐radiation processes: visible and ultraviolet A radiation (VUVA), TiO₂ adsorption, ozonation, VUVA/TiO₂ photocatalysis and VUVA/O₃/TiO₂ photocatalytic ozonation. With the exception of VUVA radiation and TiO₂ adsorption, ozone and photolytic processes allow for the total removal of gallic acid in a period between 50 and 90 min. The time taken to achieve 100% gallic acid conversion depends on the oxidation process applied, photocatalytic ozonation being the most effective technique. Throughout the process, oxalic and formic acids were identified as byproducts. Some other unidentified compounds probably related to pyruvic, malonic and maleic acids were also detected. The appearance of these compounds can be justified from direct reactions of both hydroxyl radical and ozone in water. Only photocatalytic ozonation leads to total mineralisation of the organic matter in less than 90 min. The photocatalyst used, TiO₂, showed good activity and stability (no leaching was observed) after five consecutive photocatalytic ozonation runs with the same semiconductor‐catalyst mass. Copyright © 2006 Society of Chemical Industry     

Effects of Temperature and Photocatalysts on Removal of Polycyclic Aromatic Hydrocarbons (PAHs) from Automotive Industry Sludge

This study was carried out to investigate the removability of polycyclic aromatic hydrocarbon (PAH) compounds existed in automotive industry treatment sludge. The impacts of temperature, UV, titanium dioxide (TiO₂), and diethyl amine (DEA) were studied in a controlled device which was specifically designed for this study. Sludge samples were collected from the treatment plant of an automotive manufacturing facility in Bursa, Turkey. The ∑₁₀ PAH concentration value in the sludge was 4480 ± 1450 ng/g dry matter (DM). ∑₁₀ PAH removal ratio was 30% at 37°C without UV irradiation. Moreover, the PAH content in the sludge was reduced up to 65% through applying UV irradiation. This figure reached 100% by using photo-catalysts (TiO₂ or DEA) at the rate of 20% of the DM of the sludge.     

高分子絮凝剂处理高浓度化妆品原料生产废水研究

化妆品原料生产过程中产生的废水水质成分复杂、有机物含量高、难降解，利用混凝工艺处理该废水能够减缓生化处理单元的负担，提高污水处理效率。为揭示无机高分子混凝剂混凝过程中污染物的去除机制和污泥性质的变化，考察了不同的絮凝剂聚合氯化铝（PAC）、聚合硫酸铁（PFS）、聚合氯化铝铁（PAFC）和助凝剂聚丙烯酰胺（PAM）投加浓度对污染物去除率和污泥性质的影响。采用傅里叶变换红外光谱（FTIR）、X射线能谱（EDX）、扫描电镜（SEM）、热重分析仪（TGA）分析污泥絮体官能团、表面形貌、元素组成和热稳定性的变化，采用三维荧光光谱（3D-EEM）和超滤技术分析出水中有机物分子量的分布规律和有机物成分的变化，优化最佳混凝工艺运行条件。结果表明：进水中的天然有机物（NOM）荧光强度高，有机物分子量主要分布在>100×10³和<3×10³区间，其所占比例分别为22.89%和50.57%。当进水COD为6700~7500 mg/L时，在助凝剂PAM投加浓度为0.03 g/L，PAC、PFS和PAFC投加浓度分别为2.8 g/L、2.8 g/L和3.0 g/L的条件下，COD去除率分别为87.20%、79.89%和83.74%，出水浊度分别为2.54 NTU、9.3 NTU和5.51 NTU，NOM荧光强度大大减弱。其中，PAC+PAM对废水中有机物去除效果最好，出水有机物分子量主要分布在(10~30)×10³和<3×10³范围内，其所占比例分别为31.84%和25.92%，形成的混凝污泥具有较好的热稳定性，污泥表面蓬松,呈多孔网状结构。混凝工艺可吸附脂类大分子物质，提高了高浓度化妆品原料生产废水的可生化性。     

Feasibility of Sludge Ozonation for Stabilization and Conditioning

A pilot-scale sludge treatment plant was built to investigate the feasibility of ozonation processes for waste activated sludge treatment. Ozonation of wastewater sludge resulted in mass reduction by mineralization as well as by supernatant and filtrate recycle. Another advantage of sludge ozonation is a significant improvement of settleability and dewaterability. Experimental results showed that mass reduction of 70% and volume reduction of 85% compared with the control sludge was achieved through the sludge ozonation at a dose of 0.5?gO₃/gDS. It is also interesting to note that the filterability deteriorates up to ozone dose of 0.2?gO₃/gDS and then improves considerably at a higher ozone dose. The filterability could be improved by chemical conditioning even at a low ozone dose. The economic feasibility by cost analysis reveals that ozonation processes can be more economical than other alternative processes for sludge treatment and disposal at small-sized wastewater treatment plants.     

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).