Issue 2

250 million people worldwide suffer from visual impairment. 64% of them wear glasses. More than 80 percent of all eyeglasses worn today have plastic lenses. Plastic lenses made of polycarbonate discs are created through the process of machining which requires the use of a coolant. The ensuing wastewater contains chips, water, and coolant. In the studied facility, the chips are separated by filtration. Water and coolant are returned to the machine tool. Due to the low particle weight some of the plastic dust flotates and creates foam. If there is too much foamed dust, a skimmer is added. In order to avoid machine damage and product quality deterioration, the mixture in circulation is changed every 24 hours. For the purpose of the study, wastewater was sampled from the plastic lenses facility. It was characterized by a high COD value of 11 200 - 20800 mg/L, a turbidity of 260-870 NTU, and a colour of about 200 mg/L. Wastewater with these parameters should not be discharged into the sewage system. For their treatment, a coagulation process (PAX 18 and PAX XL 19 H, Tanfloc SG) and Fenton process were applied. The application of aluminum coagulants resulted in a maximum reduction of COD of 55%. Maximum COD reduction after the Fenton process was 50.7%.

Anthracene and phenanthrene belong to a group of persistent environmental contaminants called PAHs. Evaluation of the structure of two selected PAHs i.e. anthracene and phenanthrene on their resistance to destruction by UV-activated PDS was the aim of this study. The authors focused on two aspects of this problem: - the role of the so-called ‘bay-region’, in the structure of phenanthrene, during PDS/UV oxidation - formation of substituted forms of these PAHs in the absence and presence of three nitrogen-containing compounds i.e. ammonia and nitrite or nitrate ions. Even though phenanthrene and anthracene have the same molecular formula, the difference in their ring assessment influences their degradability. Considering all the results, in all the cases anthracene was degraded faster and/or had a higher degradation rate. That proves phenanthrene to be more stable and resistant for degradation however comparison of PDS/UV systems vs. UV– irradiation alone confirms that the addition of PDS accelerates the degradation of anthracene and phenanthrene. Comparison of PDS/UV with the addition of three different nitrogen-containing compounds showed a significant difference between anthracene and phenanthrene. In the experiments with phenanthrene were observed additional peaks with an absorption maximum between 230-240 cm-1 which is characteristic of the nitro-group. Based on their absorption maximum and the addition of nitrogen-containing compounds, emerging by-products are assumed to be nitro-derivatives of phenanthrene. The results of GC/MS analysis suggest the possibility of formation of many compounds which can be formed from phenanthrene and are embedded on its skeleton. These analyzes also suggest the rearrangement of phenanthrene’s aromatic rings and formation new compounds.

Photocatalytic degradation for wastewater treatment is a method that has recently attracted attention. In this research, a synthesized composite of Fe3O4/SiO2/NiO with magnetic properties was used for the photocatalytic degradation of methylene blue dye under UV light. Furthermore, the composites were characterized using XRD, FTIR, BET surface area, SEM-EDS, VSM, and UV-DRS. The results showed that the Fe3O4/SiO2/NiO composite is magnetic with a saturation magnetization of 53.84 emu/g. The Fe3O4/SiO2/NiO composite has a surface area of 128.8 m2/g, large than Fe3O4 and Fe3O/SiO2. The Fe3O4/SiO2/NiO composite has a band gap of 2.83 eV. The photocatalytic activity of Fe3O4/SiO2/NiO composite against the methylene blue dye exhibited high degradation efficiency reaching 98.51 %. The pseudo-first-order is appropriate to describe the kinetics model of photocatalytic degradation on methylene blue dye. The decrease in the degradation efficiency of the Fe3O4/SiO2/NiO composite after 5 times for the photocatalytic degradation of methylene blue dye from 98.02 % to 94.97 % indicates that the catalyst has high stability. Considering these results, the Fe3O4/SiO2/NiO composites could be used as a potential catalyst in industrial wastewater.

The electrolytic approach was combined with radiolysis employing gamma radiation as an enhanced oxidation process to study the decomposition of 1-(4-Hydroxy-3-Methoxyphenyl) ethenone (Apocynin (ACN)). For Apocynin breakdown from effluent water, a photo-catalytic membrane reactor (PMR) was utilized with suspended and immobilised Sr-LaNiO3 with regarding to gamma irradiation. For phase procedures, the impacts of basic Sr-LaNiO3 on the PMR containing residual Sr-LaNiO3 was investigated. An RO (Reverse Osmosis) membrane was integrated by way of the PMR under continuous circumstances to improve standard of water. At such a moderate Sr-LaNiO3 dosage (0.8 g/L), ACN deterioration by the PMR with attached and immobilised Pt-LaNiO3 was similar in both methods, but improved with larger Sr-LaNiO3 doses for the reactor with coupled Pt-LaNiO3.

Water pollution has been acknowledged as an issue of concern due to recalcitrant pollutants like textile dyes. Therefore, the eco-friendly synthesis of nano-particles (NPs) through green chemistry approach from sources and materials of organic origin has not only enhanced the properties of substance at nanoscale but has also reduced the toxicological impacts on human health and the environment. In this study a successful attempt was made to synthesize TiO2 NPs by Mangifera indica leaves extract as organic source. The structural morphology was determined by carrying out FTIR, SEM, EDX and XRD techniques. The removal of Methylene Blue (MB) dye was assessed by the application of the photocatalysis technique. The experiments were designed using the RSM (CCD) approach for selected parameters such as pH, TiO2 NPs, Dye concentration and Time. The maximal dye removal efficiency of 98% was achieved at optimum conditions of 4.7 pH, 0.04g of nano photocatalyst in 250ml of dye solution having 8ppm concentration, allowed to react for 45 min. The regression coefficient value of 79.37% was determined by ANOVA for MB dye. The results clearly indicate that the application of green nanoparticles for the removal of MB dye is a feasible option to overcome with the ever-increasing issue of water pollution and environmental degradation.

The photocatalytic process as an advanced oxidation process (AOP) has gained worldwide attention in the water and wastewater industry. The photocatalytic process can be used for water and wastewater disinfection. The aim of this study was to remove coliforms and faecal coliforms from real hospital wastewater using UV and UV/N doped TiO2 photocatalytic process. Secondary wastewater samples were collected from Ali-ebne Abitaleb Hospital, Zahedan. The real wastewater samples containing N-doped TiO2 nanoparticles were exposed to UV light in a reactor. Multi-tube fermentation method (MPN/100ml) was used to count the coliform and faecal coliform bacteria and evaluate the process efficiency. The results showed that the mechanism of inactivation of coliforms and faecal coliforms by N-doped TiO2 nanoparticles and UV light followed the first-order equation, and the simultaneous application of N-doped TiO2 nanoparticles and UV light (N-doped TiO2/UV) increased the efficiency of the photocatalytic process and completely inactivated the coliforms and faecal coliforms in 10 minutes. The results of this study also showed that with increasing contact time, the removal efficiency of coliforms and faecal coliforms increased in the presence of UV light. The highest efficiency of the nanoparticles in bacterial inactivation was achieved at a dose of 120 mg/l in the presence of UV light and was 100%. The nano-photocatalytic process can be used as an efficient method to remove coliforms and faecal coliforms from hospital wastewater, and the N-doped TiO2/UV process is a reliable antibacterial method for water and wastewater disinfection.