Application of Artificial Neural Network (ANN) as a predictive tool for the removal of pharmaceutical from wastewater streams using biochar: a multifunctional technology for environment sustainability.

This study investigates biochar as an attractive option for removing pharmaceuticals from wastewater streams utilizing data from various literature sources and also explores the sensitivity of the characteristics and implementation of biochar. ANN 1 was designed to determine the optimal biochar characteristics (Surface Area, Pore Volume) to achieve the maximum percentage removal of pharmaceuticals in wastewater streams. ANN 2 was developed to identify the optimal biomass feedstock composition, pyrolysis conditions (temperature and time), and chemical activation (acid or base) to produce the optimal biochar from ANN 1. ANN 3 was developed to investigate the effectiveness of the biochar produced in ANN 1 and 2 in removing dye from water. Biomass feedstock with a high lignin content and high volatile matter at a high pyrolysis temperature, whether using an acid or base, achieves a high mesopore volume and high surface area. The biochar with the highest surface area and mesopore volume achieved the highest removal percentage. Regardless of hydrophobicity conditions, at low dosages (0.2), a high surface area and pore volume are required for a high percent removal. And with a higher dosage, a lower surface area and pore volume is necessary to achieve a high percent removal.

Optimization and screening of process parameters for the robust co-pyrolytic study of waste motor oil and rice stubble toward sustainable waste-to-fuel generation.

The current study explores the co-pyrolysis of waste motor oil (WMO) and rice stubble in a designed lab-scale pyrolyzer to produce alternative energy fuels. The parameter screening was followed by optimization utilizing the Box-Behnken design (BBD). Reactor temperature (TR), mixing ratio (M), and holding time (t) affected the co-pyro-oil yield substantially. A maximum co-pyro-oil yield of 90.3% was achieved at a TR = 485 °C, t = 12.5 min, and M = 5% rice stubble to waste motor oil, which was further characterized and compared with the commercial diesel fuel properties. The highest research octane number of 76.15 was obtained for the co-pyro-oil (Co-PO), followed by the pyro-oil generated from only waste motor oil (POWMO). Consequently, the paraffin content increased to 64.34 wt% from 27.66 wt % for PO RS. The carbon number varied from C7-C17 for PO WMO and Co-Po, aligning with the diesel fuel requirements. Furthermore, a substantial enrichment in the physio-chemical properties of the produced Co-PO with reduced moisture content and enhancement in higher heating value (HHV) was also noticed. Hence, the generated Co-PO could be utilized as transport-grade fuel.

Utilization of ferrous slags as coagulants, filters, adsorbents, neutralizers/stabilizers, catalysts, additives, and bed materials for water and wastewater treatment: A review.

Solid waste is currently produced in substantial amounts by industrial activities. While some are recycled, the majority of them are dumped in landfills. Iron and steel production leaves behind ferrous slag, which must be created organically, managed wisely and scientifically if the sector is to remain more sustainably maintained. Ferrous slag is the term for the solid waste that is produced when raw iron is smelted in ironworks and during the production of steel. Both its specific surface area and porosity are relatively high. Since these industrial waste materials are so easily accessible and offer such serious disposal challenges, the idea of their reuse in water and wastewater treatment systems is an appealing alternative. There are many components such as Fe, Na, Ca, Mg, and silicon found in ferrous slags, which make it an ideal substance for wastewater treatment. This research investigates the potential of ferrous slag as coagulants, filters, adsorbents, neutralizers/stabilizers, supplementary filler material in soil aquifers, and engineered wetland bed media to remove contaminants from water and wastewater. Ferrous slag may provide a substantial environmental risk before or after reuse, so leaching and eco-toxicological investigations are necessary. Some study revealed that the amount of heavy metal ions leached from ferrous slag conforms to industrial norms and is exceedingly safe, hence it may be employed as a new type of inexpensive material to remove contaminants from wastewater. The practical relevance and significance of these aspects are attempted to be analyzed, taking into account all recent advancements in the fields, in order to help in the development of informed decisions about future directions for research and development related to the utilization of ferrous slags for wastewater treatment.

In-situ and ex-situ co-pyrolysis studies of waste biomass with spent motor oil: Elucidating the role of physical inhibition and mixing ratio to enhance fuel quality.

Simultaneous renewable energy generation is an imperative part of sustainable hazardous waste management. Therefore, the present work explicates the co-pyrolysis of rice stubble (RS) waste biomass and spent motor oil (SMO) to upgrade the obtained bio-oil. Moreover, two different modes, namely, in-situ and ex-situ, were implemented to analyze the effect of physical inhibition. Monothetic analysis approach was followed to determine optimum process conditions. A substantial increment of âˆ¼ 85% was observed in bio-oil yield for RS: SMO (1:1) in-situ operation whilst the only RS biomass pyrolysis. Moreover, the HHV increased by âˆ¼ 2.15 times after co-pyrolysis with a considerable reduction (62.70%) in water content. Consequently, the paraffin content increased to 79.14 vol% with an iso-paraffin index of 0.285. Subsequently, a possible reaction mechanism is also proposed to evaluate results comprehensively. Altogether, the co-pyrolysis of these feedstocks resulted in improved aliphatic content and reduced oxygenates, encouraging its adequacy as an alternate fuel.

Facile method to synthesize efficient adsorbent from alumina by nitric acid activation: Batch scale defluoridation, kinetics, isotherm studies and implementation on industrial wastewater treatment.

The excess amount of fluoride contamination in the groundwater or industrial effluents fosters various health problems. Considering the advantages of adsorption, the current research reports the synthesis of a novel adsorbent (HNAA) by simple and convenient process of nitric acid activation of alumina. The physiochemical characterization (SEM, EDX, XRF, FTIR, BET, and pHZPC) results exhibited successful activation of alumina and adsorption of fluoride ions. The effect of process parameters (contact time, initial pH, adsorbent dose, initial fluoride concentration and presence of coexisting ions) on adsorption of fluoride ions on HNAA were investigated in batch scale. The adsorption of fluoride ion on HNAA followed the Freundlich isotherm and pseudo second order kinetic model. The Qmax of HNAA adsorbent was 45.75 mg/g at 45 °C. The fluoride ion adsorption was revealed to be endothermic and spontaneous. The experimentation of the HNAA adsorbent on industrial wastewater, with fluoride concentration of 17.5 mg/L, inferred the significant defluoridation potential at the optimized adsorbent dose and pH. The nitric acid activation of alumina resulted in improvement of defluoridation efficiency from 74.18% to 97.43%. The HNAA also exhibited the better regeneration and reusability features which distinguish it as a promising adsorbent to be applied for real field wastewater.

Thermodynamic spectral and kinetic analysis of the removal of Cu(II) from aqueous solution by sodium carbonate treated rice husk.

A new adsorbent for removing copper ions from aqueous solutions has been developed and characterized. The present study deals with the sorption of Cu(II) from aqueous solution on chemically pretreated sodium carbonate-treated rice husk (SCRH). The physico-chemical characteristics of rice husks were investigated to analyze their suitability to adsorb Cu(II) ions from water and wastewater. The raw rice husk (RRH), SCRH and Cu(II) adsorbed rice husk were analyzed by SEM-EDAX analysis. FTIR spectroscopy was also applied to identify functional groups, capable of adsorbing metal ions. Batch kinetic studies were conducted for the adsorption of Cu(II) on SCRH. It has been observed that 92.9-96.0% removal of Cu(II) is achieved at 4.8 mg of Cu(II)/g of adsorbent, adsorbent dose of 10 g L-1 and initial Cu(II) concentration of 10 mg L-1 in a temperature range of 15-50 °C. It was observed that the adsorption of Cu(II) on SCRH followed pseudo second-order kinetic and time to achieve equilibrium was found to be 60 min. The maximum uptake (97%) of Cu (II) was observed at pH 6. In this paper, an attempt has also been made to develop simple and readily understandable thermodynamic parameters related to sorption process at the equilibrium for understanding the adsorption mechanism. The Gibbs free energy ΔG° values for the adsorption processes of Cu(II) at 15, 30, 40 and 50 °C were calculated as -6.16, -6.84, -8.01 and -8.53 kJ mol-1, respectively. The negative value of ΔG° indicates spontaneity of adsorption. The values of ΔH° and ΔS° for Cu(II) adsorption were calculated as 14.37 kJ mol-1 and 70.92 J K-1 mol-1, respectively. The activation energy for the adsorption of Cu(II) was found to be 9 kJ mol-1 which is a characteristic for diffusion limited processes.

Modeling and optimization of process variables for HCl gas removal by response surface methodology.

In the present article, optimization of process variables has been done to maximize the removal efficiency of toxic HCl gas in a submerged self-priming venturi scrubber. Response surface methodology with central composite design has been chosen to predict the effect of process variables on the removal efficiency. A quadratic equation was found from this study to predict the removal efficiency and from the ANOVA test, the significance of process variables was evaluated. Regression analysis confirmed the suitability of the developed model by the higher R2 square value (0.9717). Optimum conditions were obtained as 55.18 m s-1 of throat gas velocity, 405.10 ppm of inlet HCl concentration and 0.0038 N of NaOH concentration in scrubbing liquid to achieve 90.80% of the HCl removal efficiency.

Defluoridation of synthetic and industrial wastewater by using acidic activated alumina adsorbent: characterization and optimization by response surface methodology.

Excessive contamination of fluoride in wastewater is the cause of several chronic health problems. For this purpose, an adsorbent was prepared from alumina by acidic activation using sulfuric acid. The current research aims to find the maximum fluoride adsorption (%) from synthetic and industrial wastewater at optimum process parameters by using response surface methodology (RSM). All batch scale experiments were carried out according to the statistical-design order. Central composite design (CCD) was applied to ascertain the effect of adsorbent dose, pH, initial fluoride concentration and temperature on fluoride adsorption (%). Maximum fluoride removal was predicted based on the quadratic model developed. Validation of the model was done with negligible error. The regression coefficient of the model was found to be 0.96. From the analysis of variance (ANOVA), the factors with the greatest effect on the adsorption of fluoride were identified. Under optimized condition, the adsorbent dose 13.89 g L-1, pH 5.52, temperature 25 °C and initial fluoride concentration 18.67 mg L-1 resulted in 96% of maximum fluoride adsorption. Under the same optimized parameters, the fluoride adsorption from industrial wastewater found to be 92.10%.

A novel acid modified alumina adsorbent with enhanced defluoridation property: Kinetics, isotherm study and applicability on industrial wastewater.

Excessive fluoride contamination in ground and surface water is hazardous to human health. Adsorptive removal is a better option for defluoridation due to its simplicity and efficient working property. In the current research, an attempt was made for the removal of fluoride ions from wastewater by a novel adsorbent synthesized with alumina and H2SO4 acid by acidic activation. The adsorbent was characterized for physio-chemical properties by several analytical methods (SEM, EDX, FTIR, XRF, TGA, XRD, HI and pHZPC). The specific surface area of acid activated alumina (AAA) adsorbent was found to be 87.44 m2/g. The batch scale experiments were conducted to study the effect of initial pH, adsorbent dose, stirring rate, and contact time on the defluoridation efficiency of AAA adsorbent. The experimental data of isotherm study was found to follow the Freundlich isotherm model. The maximum adsorption capacity of fluoride on AAA was 69.52 mg/g at 318 K. The nature of adsorption was found to be endothermic and spontaneous. The adsorption kinetic data followed the pseudo-second-order model. The fluoride removal efficiency of alumina with and without acid activation resulted in 96.72% and 63.58%, respectively. The regeneration capability, reusability, applicability on industrial effluent and economic value were investigated.

Removal of HCl gas from off gases using self-priming venturi scrubber.

Growing concern about the effect of hydrochloric acid gas (HCl) on environment and abatement of it is now a very serious issue. This present paper is focused on developing a realistic model in order to remove the HCl from the off gases using self-priming venturi scrubber. A detailed parametric study of throat gas velocity (36-72 m/s), liquid level in outer cylinder (0.40-0.77 m) and inlet concentration of HCl (100-500 ppm) on HCl removal efficiency have been done with normal water as a scrubbing liquid. Also the removal efficiency was enhanced by using NaOH solution as a scrubbing liquid in submerged and non-submerged conditions. Therefore, the maximum removal efficiency of HCl was obtained as 87.83% with normal water and 92.54% with 0.005N NaOH solution as the scrubbing liquid at inlet HCl concentration of 500 ppm, throat gas velocity of 60 m/s and liquid level of 0.77 m in submerged condition. Experimental results were validated with the developed empirical model and showed excellent agreement with less deviation.

Removal of fluoride from wastewater using HCl-treated activated alumina in a ribbed hydrocyclone separator.

Excessive fluoride concentration in wastewater is a major health concern worldwide. The main objective of wastewater treatment is to allow industrial effluents to be disposed of without danger to the human health and the natural environment. In this current study, experiments have been conducted to remove fluoride from aqueous solution using alumina and HCl (Hydrochloric acid) treated activated alumina in a continuous mode. A spiral rib was introduced in the cylindrical part of the conventional hydrocyclone to increase the performance, and the new hydrocyclone is dubbed as ribbed hydrocyclone. Experiments were carried out to analyze the performance of the ribbed hydrocyclone and compared the results with the conventional hydrocyclone of the same dimension. The efficiency of conventional and ribbed hydrocyclone at a slurry flow rate of 50 LPM (liter per minute) for the solid concentration of 1.4 wt% were 80% and 93.5% respectively. The cut size d50 of the conventional and ribbed hydrocyclone was 18 µm and 13 µm respectively at a slurry velocity of 50 LPM. Fluoride removal efficiency using alumina and HCl-treated alumina was also investigated in a continuous mode by the ribbed hydrocyclone. Maximum fluoride removal efficiency was 49.5%, and 80% for alumina and HCl-treated alumina for the initial concentration of 10 mg/L at a slurry flow rate of 50 LPM.

Removal of H2S pollutant from gasifier syngas by a multistage dual-flow sieve plate column wet scrubber.

The objective of this study was to observe the performance of a lab-scale three-stage dual-flow sieve plate column scrubber for hydrogen sulfide (H2S) gas removal from a gas stream, in which the H2S concentration was similar to that of gasifier syngas. The tap water was used as scrubbing liquid. The gas and liquid were operated at flow rates in the range of 16.59 × 10-4-27.65 × 10-4 Nm3/s and 20.649 × 10-6-48.183 × 10-6 m3/s, respectively. The effects of gas and liquid flow rates on the percentage removal of H2S were studied at 50-300 ppm inlet concentrations of H2S. The increase in liquid flow rate, gas flow rate and inlet H2S concentration increased the percentage removal of H2S. The maximum of 78.88% removal of H2S was observed at 27.65 × 10-4 Nm3/s gas flow rate and 48.183 × 10-6 m3/s liquid flow rate for 300 ppm inlet concentration of H2S. A model has also been developed to predict the H2S gas removal by using the results from the experiments and adding the parameters that affect the scrubber's performance. The deviations between experimental and predicted H2S percentage removal values were observed as less than 16%.

Optimization process parameters for in-situ synthesis of ammonia by catalytic hydrolysis of urea with fly ash in a batch reactor for safe feedstock in power plants.

In this study, catalytic urea hydrolysis for production of ammonia in presence of fly ash, at optimum condition, was investigated in a batch reactor. The single and combined effects of operating parameters such as initial feed concentrations, temperature, fly ash doses, times and stirring speed on the production of ammonia from urea were analyzed using response surface methodology. A 2(5) full factorial central composite experimental design was employed. Analysis of variance (ANOVA) showed a high coefficient of determination value (R(2)= 0.963) and satisfactory prediction second order regression model was derived. The optimum production conditions were determined as initial feed concentration 19.9 wt. % of urea, temperature 175°C, fly ash dose 7.5 g/L, reaction time 25 min and stirring speed 769 rpm. At optimum conversion conditions, the conversion of urea for production of ammonia was found to be 99.8 %.

Modeling the operation of a three-stage fluidized bed reactor for removing CO2 from flue gases.

A bubbling counter-current multistage fluidized bed reactor for the sorption of carbon dioxide (CO(2)) by hydrated lime particles was simulated employing a two-phase model, with the bubble phase assumed to be in plug flow, and the emulsion phase in plug flow and perfectly mixed flow conditions. To meet prescribed permissible limit to emit carbon dioxide from industrial flue gases, dry scrubbing of CO(2) was realized. For the evaluation, a pilot plant was built, on which also the removal efficiency of CO(2) was verified at different solids flow rates. The model results were compared with experimental data in terms of percentage removal efficiency of carbon dioxide. The comparison showed that the EGPF model agreed well with the experimental data satisfactorily. The removal efficiency was observed to be mainly influenced by flow rates of adsorbent and CO(2) concentration.

Statistical modelling and optimization of hydrolysis of urea to generate ammonia for flue gas conditioning.

The present study is concerned with the technique of producing a relatively small quantity of ammonia which can be used safely in a coal-fired thermal power plant to improve the efficiency of electrostatic precipitator by removing the suspended particulate material mostly fly ash, from the flue gas. In this work hydrolysis of urea has been conducted in a batch reactor at atmospheric pressure to study the different reaction variables such as reaction temperature, initial concentration and stirring speed on the conversion by using design expert software. A 2(3) full factorial central composite design (CCD) has been employed and a quadratic model equation has been developed. The study reveals that conversion increases exponentially with an increase in temperature, stirring speed and feed concentration. However the stirring speed has the greatest effect on the conversion with concentration and temperature exerting least and moderate effect respectively. The values of equilibrium conversion obtained through the developed models are found to agree well with their corresponding experimental counterparts with a satisfactory correlation coefficient of 93%. The developed quadratic model was optimized using quadratic programming to maximize conversion of urea within experimental range studied. The optimum production condition has been found to be at the temperature of 130 degrees C, feed concentration of 4.16 mol/l and stirring speed of 400 rpm and the corresponding conversion, 63.242%.

Kinetic studies on hydrolysis of urea in a semi-batch reactor at atmospheric pressure for safe use of ammonia in a power plant for flue gas conditioning.

With growing industrialization in power sector, air is being polluted with a host of substances-most conspicuously with suspended particulate matter emanating from coal-fired thermal power plants. Flue gas conditioning, especially in such power plants, requires in situ generation of ammonia. In the present paper, experiments for kinetic study of hydrolysis of urea have been conducted using a borosil glass reactor, first without stirring followed by with stirring. The study reveals that conversion increases exponentially with an increase in temperature and feed concentration. Furthermore, the effect of stirring speed, temperature and concentration on conversion has been studied. Using collision theory, temperature dependency of forward rate constant has been developed from which activation energy of the reaction and the frequency factors have been calculated. It has been observed that the forward rate constant increases with an increase in temperature. The activation energy and frequency factor with stirring has been found to be 59.85 kJ/mol and 3.9 x 10(6)min(-1) respectively with correlation co-efficient and standard deviation being 0.98% and +/-0.1% in that order.

Optimization of production conditions for activated carbons from Tamarind wood by zinc chloride using response surface methodology.

The low-cost activated carbon was prepared from Tamarind wood an agricultural waste material, by chemical activation with zinc chloride. Activated carbon adsorption is an effective means for reducing organic chemicals, chlorine, heavy metals and unpleasant tastes and odours in effluent or colored substances from gas or liquid streams. Central composite design (CCD) was applied to study the influence of activation temperature, chemical ratio of zinc chloride to Tamarind wood and activation time on the chemical activation process of Tamarind wood. Two quadratic models were developed for yield of activated carbon and adsorption of malachite green oxalate using Design-Expert software. The models were used to calculate the optimum operating conditions for production of activated carbon providing a compromise between yield and adsorption of the process. The yield (45.26 wt.%) and adsorption (99.9%) of the activated carbon produced at these operating conditions showed an excellent agreement with the amounts predicted by the models.

Response surface modeling and optimization of chromium(VI) removal from aqueous solution using Tamarind wood activated carbon in batch process.

The present paper discusses response surface methodology (RSM) as an efficient approach for predictive model building and optimization of chromium adsorption on developed activated carbon. In this work the application of RSM is presented for optimizing the removal of Cr(VI) ions from aqua solutions using activated carbon as adsorbent. All experiments were performed according to statistical designs in order to develop the predictive regression models used for optimization. The optimization of adsorption of chromium on activated carbon was carried out to ensure a high adsorption efficiency at low adsorbent dose and high initial concentration of Cr(VI). While the goal of adsorption of chromium optimization was to improve adsorption conditions in batch process, i.e., to minimize the adsorbent dose and to increase the initial concentration of Cr(VI). In the adsorption experiments a laboratory developed Tamarind wood activated carbon made of chemical activation (zinc chloride) was used. A 2(4) full factorial central composite design experimental design was employed. Analysis of variance (ANOVA) showed a high coefficient of determination value (R(2)=0.928) and satisfactory prediction second-order regression model was derived. Maximum chromium removal efficiency was predicted and experimentally validated. The optimum adsorbent dose, temperature, initial concentration of Cr(VI) and initial pH of the Cr(VI) solution were found to be 4.3g/l, 32 degrees C, 20.15 mg/l and 5.41 respectively. Under optimal value of process parameters, high removal (>89%) was obtained for Cr(VI).

Removal of hazardous gaseous pollutants from industrial flue gases by a novel multi-stage fluidized bed desulfurizer.

Sulfur dioxide and other sulfur compounds are generated as primary pollutants from the major industries such as sulfuric acid plants, cupper smelters, catalytic cracking units, etc. and cause acid rain. To remove the SO(2) from waste flue gas a three-stage counter-current multi-stage fluidized bed adsorber was developed as desulfurization equipment and operated in continuous bubbling fluidization regime for the two-phase system. This paper represents the desulfurization of gas mixtures by chemical sorption of sulfur dioxide on porous granular calcium oxide particles in the reactor at ambient temperature. The advantages of the multi-stage fluidized bed reactor are of high mass transfer and high gas-solid residence time that can enhance the removal of acid gas at low temperature by dry method. Experiments were carried out in the bubbling fluidization regime supported by visual observation. The effects of the operating parameters such as sorbent (lime) flow rate, superficial gas velocity, and the weir height on SO(2) removal efficiency in the multistage fluidized bed are reported. The results have indicated that the removal efficiency of the sulfur dioxide was found to be 65% at high solid flow rate (2.0 kg/h) corresponding to lower gas velocity (0.265 m/s), wier height of 70 mm and SO(2) concentration of 500 ppm at room temperature.

Equilibrium studies on hydrolysis of urea in a semi-batch reactor for production of ammonia to reduce hazardous pollutants from flue gases.

The increasing environmental awareness and the mandate of the pollution control agencies in various part of country for lowering emission of air pollutants such as CO(2), NO(x), SO(2) and fly ash emissions, has increased the urgency for reviewing options and alternatives to accomplish the above objective. The addition of ammonia into the flue gas stream as a conditioning agent is found to be used in recent years for the reduction of air pollutants. Flue gas conditioning requires in situ generation of ammonia as the transportation and storage of anhydrous ammonia is hazardous in nature. The equilibrium study on hydrolysis of urea was done in a semi-batch glass reactor to investigate the effect of reaction temperature, initial feed concentration and stirring speed on ammonia production. Few experiments were carried out in a semi-batch reactor at atmospheric pressure by using different concentration of urea solution from 10 to 40 wt% of urea to water and equilibrium study has been done. The study reveals that conversion increases exponentially with an increase in temperature but the conversion decreases with increase in the inlet feed concentration of urea solution. Furthermore, the effect of stirring speed on conversion has also been studied and it found that conversion increases with increase in stirring speed.