Diclofenac sodium and paracetamol removal with ZnCl2 activated carbon produced from rice straw.

This study explored the efficacy of activated carbon derived from rice straw and treated with ZnCl2 (ZnCl2-RS) for the removal of diclofenac sodium (DCF) and paracetamol (PCM) through an adsorption process. The investigation included examining the variations in removal efficiency at different pH levels and ZnCl2-RS doses. The characteristics of the ZnCl2-RS, prepared for the study, were determined through SEM and FTIR analyses, revealing a composition of 49.4% carbon and 8.3% zinc. At pH 5, the adsorption efficiency for DCF and PCM was enhanced, achieving removal rates of 92.2% for DCF and 89.1% for PCM with 0.2 g of ZnCl2-RS. The adsorption of DCF and PCM by ZnCl2-RS followed pseudo-second-order kinetic and adhered to the Langmuir isotherm model. The maximum adsorption capacities were calculated as 26.04 mg/g for DCF and 19.05 mg/g for PCM. In conclusion, the cost-effective production of activated carbon from agricultural waste like rice straw yielded a promising adsorbent material for efficiently removing pharmaceuticals such as diclofenac sodium and paracetamol. This approach not only contributes to waste reduction but also promotes the repurposing of agricultural waste materials.

This study is about the preparation of rice straw, which is produced as agricultural waste, by ZnCl₂ activation and the usability of the prepared adsorbent material in the purification of drugs used as analgesics such as diclofenac sodium and paracetamol. Although there are studies on the use of activated carbon produced from rice straw in the removal of pollutants such as dye, studies on drug removal are quite limited.

Comparison of kinetics and costs of Fenton and photo-Fenton processes used for the treatment of a textile industry wastewater.

In this study, the treatment of textile industrial wastewater by Fenton and Photo-Fenton oxidation processes was investigated. For this purpose, the pH, Fe2+ and H2O2 concentrations with the best organic matter and color removal were determined in the Fenton process and comparison with Fenton was made by Photo-Fenton oxidation at the optimal Fe2+/H2O2 ratio. The influent COD and TOC values of the wastewater used in the study were 848 mg/L and 253 mg/L, respectively. With the Fenton process, the best organic matter and color removal was obtained at pH 3, at 200 mg/L Fe2+ and 300 mg/L H2O2 concentrations. Under these conditions, 88.9% COD, 84.2% TOC and over 97% color removal were obtained with Fenton oxidation, and 93.2% COD, 88.9% TOC and 98% color were obtained with Photo-Fenton oxidation. However, when Fe2+ and H2O2 amounts were reduced to 50 mg/L and 75 mg/L, both organic matter and color removal were reduced with Fenton process, while higher organic matter removal and color removal were achieved with Photo-Fenton process. The total cost was changed between 9.56-16.88 €/m3 and 13.46-20.13 €/m3 with Fenton and Photo-Fenton oxidation process for all Fe2+/H2O2 ratios, respectively. With the Photo-Fenton oxidation process, higher organic matter removal was obtained at optimum Fe2+ and H2O2 concentrations. In addition, less Fe2+ and H2O2 chemicals were used in Photo-Fenton oxidation process to achieve the same removal efficiency compared to the Fenton oxidation process.

The impact of COVID-19 pandemic in medical waste amounts: a case study from a high-populated city of Turkey.

In this study, the amount of medical waste generated in a high-populated city in Turkey between January 2018 and August 2021 was evaluated, and the effect of the COVID-19 pandemic on waste amounts and waste production rate was investigated. While a total of 79,027 kg/month of medical waste was produced in the city before COVID-19, this value reached 116,714 kg/month after COVID-19. The increase in the amount of medical waste due to the COVID-19 pandemic in the province was calculated as 48% on average. It was determined that 75% of this waste amount originates from public hospitals in the city. While the production of medical waste was 0.86 kg/bed day in the pre-COVID-19 period, this value increased to 0.96 kg/bed day in 2020 and to 1.34 kg/bed day in 2021 with the COVID-19 pandemic. According to the results obtained, the amount of medical waste reached in the province due to COVID-19 is the amount of medical waste expected to be generated in the 2040s under normal conditions. It is a very important issue in terms of public health that the capacity of waste disposal in medical waste management in cities is flexible to respond to severe epidemic conditions. Based on the information obtained within the scope of the study, changes in the amount of medical waste in a city with a dense population under pandemic conditions can be obtained based on real data and projections regarding disposal capacity can be made more realistically. Supplementary Information: The online version contains supplementary material available at 10.1007/s10163-022-01428-3.

Treatment of organic peroxide containing wastewater and water recovery by fenton-adsorption and fenton-nanofiltration processes.

Treatment of organic peroxide-containing chemical industry wastewater by oxidation methods and recovery of water by the adsorption and nanofiltration (NP010) methods were investigated in this study. The COD and TOC removal rates were obtained as 72.8% and 58.0% in Fenton oxidation and were improved to 78.8% and 59.2% using photo-Fenton oxidation in the same conditions after 5 h of oxidation, respectively. The Fenton-treated wastewater was passed through nanofiltration to remove the organics and recover of the wastewater. The maximum COD removal efficiency of the NP010 membrane varied between 25% and 30% at all pH values. At low and high pH values (pH: 2.5 and pH: 11), as the filtration time increased, the COD removal efficiencies increased, and the highest COD removal efficiencies were obtained in the 180th and 210th minutes. The increase in the COD removal over time at low and high pH was related to the thickness of the filter layer and surface load balance accumulated on the filter surface. By Fenton oxidation coupling with adsorption, 81% of COD (decreased from 10,055 mg/L to 1906 mg/L) and 75.2% of TOC (decreased from 2597 mg/L to 645.4 mg/L) removal could be obtained, while 83.3% of COD (decreased from 9978 mg/L to 1664 mg/L) and 71.1% of TOC (decreased from 2597 mg/L to 750 mg/L) removal could be achieved using Fenton oxidation coupling with nanofiltration (P: 4 bar, pH: 11). In nanofiltration, the filtrate amounts were measured as 41.11 L/m2.h and 38.33 L/m2.h, respectively, at 4 bar and 6 bar of filter pressure and 30 min of filtration time. The increase in filtration time and filter pressure caused a decrease in the amount of the filtrate due to the rapid clogging of the filter pores.

Determination of the color removal efficiency of laccase enzyme depending on dye class and chromophore.

The aim of this article was to clarify which type of dye chromophores could be decolorized efficiently with the use of laccase enzyme. For this purpose, enzymatic degradation of different type of dye classes (4 reactive, 2 acid and 1 basic dye) having various chromophore groups was investigated by using commercial laccase from Cerrena unicolor. It was observed that the chromophore structure of dye is very important on enzymatic color removal efficiency. According to the experimental results, it was found that color removal efficiencies (20 mg/L initial dye) were 98.7% for RB220 (0.1 g/L enzyme after 6 h), 95.1% for RB19 (0.1 g/L enzyme after 48 h), 90.8% for AR42 (0.1 g/L enzyme after 48 h) while they were 60.9% for AR114 (0.25 g/L enzyme), 58.6% for RB21 (0.5 g/L enzyme), 39.7% for RR239 (0.25 g/L enzyme) even after seven days. As a result, it can be said that the highest decolorization rate was achieved for the reactive dye having formazan copper complex (RB220) chromophore. On the other hand, the enzymatic degradation of basic dye (BB9) was found to be rather difficult compared to the acid and reactive dyes used in this study and the maximum color removal was 42.8% after seven days.

Removal of COD, aromaticity and color of a pretreated chemical producing industrial wastewater: a comparison between adsorption, ozonation, and advanced oxidation processes.

A wide range of products are produced in the chemical producing industry such as textile dyes, chemicals, printing dyes and chemicals, paper chemicals, electrostatic powder dyes, and optical brighteners. The aim of this study is to investigate the treatability of chemical oxygen demand (COD), aromaticity, and color in the wastewater of this sector, where highly complex chemicals are used. Most of the studies in the literature are related to the treatment of synthetically prepared dyed wastewater. This study is important as it is carried out with real wastewater and gives results of many treatment methods. In the study, COD, UV-vis absorbance, and color values were attempted to be removed from the wastewater of a chemical producing industry that was pretreated by coagulation-flocculation. The COD value of the pretreated wastewater discharged to the central treatment system was restricted as 1000 mg/L. Pretreated wastewater characterization is as follows: COD: 2117 mg/L, UV-vis absorbance values at; 254 nm: 9.91, 280 nm: 8.65, 341 nm: 12.77, 436 nm: 5.01, 525 nm: 2.24, and 620 nm: 1.59. In the study, adsorption, ozonation, and advanced oxidation processes (Fenton and persulfate oxidation) were used to remove COD and UV-vis absorbance values (aromaticity, organics, and color). The method by which the best removal efficiency was obtained for all parameters was the adsorption process using powdered activated carbon (PAC). The equilibrium PAC dose was found as 6 g/L. At this adsorbent dose, the removal efficiencies of UV-vis absorbance values were all around 99% and the efficiency of COD removal was 77%. The Langmuir isotherm constants were found to be qmax= 30.4 mg/g and KL = 487.9 (L/mg). The COD concentration at this adsorbent dose was 486 mg/L and wastewater was suitable for discharge to the central wastewater treatment plant in that region.

Comparison of Fenton process and adsorption method for treatment of industrial container and drum cleaning industry wastewater.

The present study aims to explore the characterization of industrial container and drum cleaning (ICDC) industry wastewater and treatment alternatives of this wastewater using Fenton and adsorption processes. Wastewater derived from ICDC industry is usually treated by chemical coagulation and biological treatment in Turkey and then discharged in a centralized wastewater treatment facility. It is required that the wastewater COD is below 1500 mg/L to treat in a centralized wastewater treatment facility. The wastewater samples were characterized for parameters of pH, conductivity, COD, BOD5, TSS, NH3-N, TN, TOC, TP, Cd, Cr, Cu, Fe, Ni, Pb, Zn, and Hg. Initial COD values were in the range of 11,300-14,200 mg/L. The optimum conditions for Fenton treatment were 35-40 g/L for H2O2, 2-5 g/L for Fe2+, and 13-36 for H2O2/Fe2+ molar ratio. The optimum conditions of PAC doses and contact times in adsorption studies were 20-30 g/L and 5-12 h, respectively. Removal efficiencies of characterized parameters for the three samples were compared for both Fenton and adsorption processes under optimum conditions. The results suggest that these wastewaters are suitable for discharge to a centralized wastewater treatment plant.