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This study investigates the effect of two different iron compounds (zero-valent iron nanoparticle: nZVI and iron oxide nanoparticles: nIO) and pH on fermentative biohydrogen production from molasses-based distillery wastewater. The nZVI and nIO of optimum particle sizes of 50 nm and 55 nm respectively were synthesized and applied for fermentative hydrogen (H2) production. The addition of nIO & nZVI at (0.7 g/L, pH: 6) resulted in the highest H2 yield, H2 production rate, H2 content and COD reduction. Moreover, the kinetic parameters of H2 production potential (P) and H2 production rate (Rm) increased to 387 mL, and 22.2 mL/h, respectively for nZVI, these values were 363 mL and 21.8 mL/h for nIO. The results obtained indicated the positive effect of nZVI and nIO addition on enhanced fermentative H2 production. The addition of nZVI & nIO resulted in 71% and 69.4% enhancement in biohydrogen production respectively.

The effectiveness of O3, O3/Fe2+, and O3/nZVI processes on biomethanated distillery wastewater (BMDWW) was evaluated in terms of biodegradability index (BI) enhancement, biofuel production, COD, color & toxicity reduction. A significant increase in biodegradability, COD, color and toxicity reduction was observed in O3/nZVI compared with O3, O3/Fe2+ due to more hydroxyl radical production. The O3/nZVI pretreated wastewater with enhanced BI (up to 0.71) showed 60% COD removal with additional biogas generation (64% methane content). From the Gas Chromatography Mass Spectrometry (GC-MS) analysis, 18 foremost organic compounds were predominantly detected in the raw distillery wastewater. The disappearance of the corresponding FTIR (Fourier Transform Infrared Spectroscopy) & GC-MS spectra during pretreatment processes signified the degradation or transformation of the recalcitrant present in the distillery wastewater. Subsequent (AnO + AO, AO) of pretreated BMDWW resulted in biodegradation rate enhancement by (1.83, 1.67), (3.5, 2.4) and (4.7, 2.9) times for O3, O3/Fe2+ and O3/nZVI processes respectively.

Composting is a biological process in which the organic matter is degraded by the mixed population of microorganisms in a moist aerobic environment to more stable and humidified end products. The composting process involves an interaction between the organic waste, microorganisms, moisture and oxygen. The molasses-based biomethanated distillery wastewater is presently effectively utilized with sugarcane pressmud through the composting process. The aim of present work was to evaluate the effect of ozone pretreatment on the rate of composting process and the quality of compost obtained. The GC-MS & FTIR analysis of ozone pretreated wastewater indicated the degradation and/or transformation of the organic compounds to simpler compounds present in the wastewater. Composting was performed by mixing fixed weight ratios of pressmud and different ratios of ozone pretreated wastewater (1:3, 1:4 and 1:5). The composting process was found to occur faster in the ozone pretreated wastewater for all the ratios as compared to the untreated wastewater. The final compost characteristics were found to be optimum for the 1:3 and 1:4 ratios of pressmud and wastewater. The bio-oxidative phase duration of composting has been reduced for the ozone pretreated wastewater.

The study reports the biodegradability enhancement of pharmaceutical wastewater along with COD (Chemical Oxygen Demand) color and toxicity removal via O3, O3/Fe2+, O3/nZVI (nano zero valent iron) processes. Nano catalytic ozonation process (O3/nZVI) showed the highest biodegradability (BI = BOD5/COD) enhancement of pharmaceutical wastewater up to 0.63 from 0.18 of control with a COD, color and toxicity removal of 62.3%, 93% and 82% respectively. The disappearance of the corresponding Fourier transform infrared (FTIR) and gas chromatography–mass spectrometry (GC–MS) peaks after pretreatment indicated the degradation or transformation of the refractory organic compounds to more biodegradable organic compounds. The subsequent aerobic degradation study of pretreated pharmaceutical wastewater resulted in biodegradation rate enhancement of 5.31, 2.97, and 1.22 times for O3/nZVI O3/Fe2+ and O3 processes respectively. Seed germination test using spinach (Spinacia oleracea) seeds established the toxicity removal of pretreated pharmaceutical wastewater.

The present study reports the feasibility of ozone oxidation as a pretreatment option for biohydrogen production from complex biomethanated distillery wastewater with complications of low biodegrad...

This work investigated the effect of Fenton, ozone and peroxone pretreatment process on yard waste for biogas production enhancement through breakdown of complex lignocellulosic structure. The pretreatment of yard waste was carried out at different experimental conditions of Fenton (ratio: 1:5, 1:10, 1:20, 1:30, 1:40 and 1: 50; doses; 200 mgL−1: 4000 mgL−1 to 800 mgL−1: 16000 mgL−1; time: 30 min–120 min), ozone (pH: 3, 5, 7 & 9; ozone dosage:0.2 g h−1 to 2.5 g h−1; time: 15 min–60 min), and peroxone (doses: 1 mL to 5 mL) to obtain maximum biogas production. The results indicated that cellulose, hemicellulose and lignin content of yard waste decreased during pretreatment process with increased TRS concentration and in turn improves the biogas production. Pretreatment of yard waste using peroxone process resulted in maximum enhancement of TRS concentration up to 470 mg g−1 biomass from initial value of 55.3 mg g−1 biomass at an optimized condition of ozone dose of 1.8 g h−1 for 30 min with 1 mL H2O2 at pH 3. Subsequently, peroxone pretreatment showed the highest biogas production of 210 mL g−1 VS (63% CH4) as compared to control only 80 mL g−1 VS (35% CH4). The GC-MS and FTIR analysis of pretreated yard waste confirms the degradation of complex lignocellulosic structure.

Ozone is a strong oxidant and have been effectively used for the degradation and mineralization of organic pollutants. However, the increase in the toxicity and disposal of the recalcitrant organics standalone ozonation process is not effective and sustainable solution for the treatment of industrial wastewater containing recalcitrant. It is therefore necessary to provide a summary of success of hybrid ozonation process for industrial wastewater treatment along with the reaction mechanism for enhancing the molecular ozone reactivity. The paper presents a detailed review of hybrid ozonation process as a combination of two different techniques to enhance the hydroxyl radical formation thereby increasing the process efficiency. An extensive review on the mechanism and application of these hybrid ozonation processes for degradation, mineralization, detoxification of different organic pollutants present in the industrial wastewater is reported.

The study investigates the effect of catalytic ozone pretreatment via Fe2+ and nZVI on biodegradability enhancement of complex textile effluent. The nZVI particles were synthesized and characterized by XRD, TEM and SEM analyses. Results showed that nano catalytic ozone pretreatment led to higher biodegradability index (BOD5/COD = BI) enhancement up to 0.61 (134.6%) along with COD, color and toxicity removal up to 73.5%, 87%, and 92% respectively. The disappearance of the corresponding GC MS & FTIR spectral peaks during catalyzed ozonation process indicated the cleavage of chromophore group and degradation of organic compounds present in the textile effluent. Subsequent aerobic biodegradation of nZVI pretreated textile effluent resulted in maximum COD and color reduction of 78% and 98.5% respectively, whereas the untreated effluent (BI = 0.26) indicated poor COD and color reduction of only 31% and 33% respectively. Bio-kinetic parameters also confirmed the increased rate of bio-oxidation at enhanced BIs. Seed germination test using seeds of Spinach (Spinacia oleracea), indicated the effectiveness of nano catalyzed ozone pretreatment in removing toxicity from contaminated textile effluent.

The treatment of a complex pharmaceutical effluent using a combination of ozonation and biological treatment is reported with the use of ozonation as a pre- and posttreatment. Pretreatment facilitated biodegradability index (BI = BOD/COD) enhancement of up to 0.44 along with COD and color reduction of up to 42% and 33%, respectively. Subsequent anaerobic biodegradation of effluent indicated negligible biogas generation; however, aerobic biodegradation of pretreated effluent resulted in COD reduction (73%) and color reduction (62%), which was also indicated by the biokinetic parameters. Further, ozonation as a posttreatment led to higher overall COD (87%) and color (93%) removal.

The study evaluates the effect of ozone pretreatment on biodegradability enhancement of biomethanated distillery effluent. Results revealed that ozone pretreatment led to biodegradability index (BI = BOD/COD) enhancement up to 0.58 along with COD, color and toxicity reduction of up to 33%, 25% and 40%, respectively. Anaerobic digestion of pretreated effluent resulted in favorable biogas generation with methane content, yield and COD reduction of up to 62%, 39 mL/g COD and 57%, respectively. Kinetics of biogas generation determined by modified Gompertz model indicated methane production potential and production rate of 48.08 mL/g COD and 8.085 mL/g COD.day respectively under optimal conditions.

In this study, the comparative performance of coagulation, ozone, coagulation + ozone + coagulation and potassium ferrate processes to remove chemical oxygen demand (COD), color, and toxicity from a highly polluted textile wastewater were evaluated. Experimental results showed that ferrate alone had no effect on COD, color and toxicity removal. Whereas, in combination with FeSO4, it has shown the highest removal efficiency of 96.5%, 83% and 75% for respective parameters at the optimal dose of 40 mgL−1 + 3 ml FeSO4 (1 M) in comparison with other processes. A seed germination test using seeds of Spinach (Spinacia oleracea) also indicated that ferrate was more effective in removing toxicity from contaminated textile wastewater. Potassium ferrate also produces less sludge with maximum contaminant removal, thereby making the process more economically feasible. Fourier transform infrared spectroscopy (FTIR) analysis also shows the cleavage of the chromophore group and degradation of textile wastewater during chemical and oxidation treatment processes.

Kinetics of nano-catalysed dark fermentative biohydrogen production from molasses-based distillery wastewater has been reported. Iron oxide nanoparticle was supplemented (10-200 mgL -1 ) to the wastewater to enhance the biohydrogen production. Andrew's inhibition model was employed to evaluate the rate of hydrogen production (R H2 ) and hydrogen yield at different concentration of iron oxide nanoparticles. The maximum R H2 and specific hydrogen yield (SHY) for the fermentative hydrogen production system at different concentration of iron oxide nanoparticle were found to be 80.7 ml/hr and 44.28 ml H 2 /g COD. Michaelis-Menton equation was applied to determine the rate of hydrogen production (R H2 ) and yield of H 2 (SHY) at different initial pH (5, 6 & 7). Andrew's inhibition model has been used to describe the inhibitory effect of substrate concentration on the rate of H2 production (R H2 ). R H2 decreased with the increase in substrate concentration but SHY first decreased with substrate concentration and it is maximum at higher substrate concentration of 110 gL -1 . Monod model has been used to determine the growth kinetic parameters. The values of maximum rates of microbial growth (μ m ) and substrate utilization (R su ) were 0.1 g biomass/g biomass/day and 14.03 g COD/g biomass/day respectively at different iron oxide nanoparticles concentration.

In recent years, complex industrial wastewater generated from distillery, heterocyclic, pharmaceutical, chemical manufacturing industries, and so on, has become a major area of concern. These complex efuents are characterized by high chemical oxygen demad (COD), color, presence of recalcitrant intermediates and poor biodegradability, which warrant the need for efcient and sustainable processes for their treatment. Conventional biological treatment processes have severe limitations due to the high recalcitrant nature of these efuents, which often results in ineffective treatment. Alternative physicochemical options are capital and energy intensive and also may generate secondary waste streams. The advanced oxidation processes (AOP) such as wet air oxidation (WAO), ozonation, UV, H2O2, and the like, are emerging techniques and have immense potential for effective treatment of complex efuents. AOPs are characterized by generation of hydroxyl radicals that are highly reactive and can easily degrade/alter/modify recalcitrant/toxic contaminants. They are, however, presently beset with problems of high capital and energy intensiveness and are unsustainable as standalone options. The synergistic combination of AOP pretreatment of complex efuent for biodegradability enhancement followed by biological treatment has potential for providing high treatment efciency along with high overall sustainability. Therefore, the primary emphasis of any advanced oxidative pretreatment process should be on partial oxidation/minimal mineralization leading to the formation of biologically degradable intermediates. Minimum mineralization ensures the process feasibility and economics. This chapter discusses WAO and ozonation as pretreatment options for complex efuent to enhance biodegradability to facilitate subsequent biodegradation via anaerobic and aerobic biological processes. Discussions pertaining to the recent developments in this area along with future challenges and prospects exemplied through relevant case studies are presented.

Biofiltration is emerging as a promising cost effective technique for the Volatile Organic Compounds (VOCs) removal from industrial waste gases. In the present investigation a comparative modeling study has been carried out using Radial Basis Function Neural Network (RBFN) and Response Surface Methodology (RSM) to predict and optimize the performance of a biofilter system treating toluene (a model VOC). Experimental biofilter system performance data collected over a time period by daily measurement of inlet VOC concentration, retention time, pH, temperature and packing moisture content was used to develop the mathematical model. These independent variables acted as the inputs to the mathematical model developed using RSM and RBFN, while the VOC removal efficiency was the biofilter system performance parameter to be predicted. The data set was divided into two parts: 60% of data was used for training phase and remaining 40% of data was used for the testing phase. The average % error for RSM and RBFN were 7.76% and 3.03%, and R2 value obtained were 0.8826 and 0.9755 respectively. The results indicated the superiority of RBFN in the prediction capability due to its ability to approximate higher degree of nonlinearity between the input and output variables. The optimization of biofilter parameters was also done using RSM to optimize the biofilter performance. RSM being structured in nature enabled the study of interaction effect between the independent variables on biofilter performance.

The effluents from molasses-based distilleries after biomethanation are beset with problems of intensified dark brown color, high residual COD, low biodegradability index (BOD/COD ratio

The present study reports the feasibility of Wet Air Oxidation (WAO) as a pretreatment option for enhanced biodegradation of complex distillery effluent. Initially, the distillery effluent was pretreated by WAO at different process conditions (pressure, temperature and time) to facilitate enhancement in the biodegradability index (BI = BOD5: COD ratio). The biodegradability of WAO pretreated effluent was evaluated by subjecting it to aerobic biodegradation and anaerobic followed by aerobic biodegradation. Aerobic biodegradation of pretreated effluent with enhanced biodegradability index (BI = 0.4–0.8) showed enhanced COD reduction of up to 67.7%, whereas the untreated effluent (BI = 0.17) indicated poor COD reduction of only 22.5%. Anaerobic followed by aerobic biodegradation of pretreated effluent has shown up to 87.9% COD reduction, while the untreated effluent has shown only 43.1% COD reduction. Bio-kinetic parameters also confirmed the increased rate of bio-oxidation at enhanced BIs. The results indicate that the WAO pretreatment facilitates enhanced bio-oxidation/bio-degradation of complex effluents like the distillery spent wash.