Optimization of wastewater treatment systems for growing industrial parks.

Wastewater treatment is one of the crucial functions of industrial parks as wastewater from industrial facilities usually contains toxic compounds that can cause damage to the environment. To control their environmental loads, industrial parks make investment decisions for wastewater treatment plants. For this, they need to consider technical and economic factors as well as future growth projections as substantial construction and operational costs of wastewater treatment plants have to be shared by all companies in an industrial park. In this paper, we consider the long-term capacity planning problem for wastewater treatment facilities of a stochastically growing industrial park. By explicitly modeling randomness in the arrival of new tenants and their random wastewater discharges, our model calculates the future mean and variance of wastewater flow in the industrial park. Mean and variance are used in a Mixed Integer Programming Model to optimize wastewater treatment plant selection over a long planning horizon (30 years). By fitting our first model to empirical data from an industrial park in Turkey, we find that considering the variance of wastewater load is critical for long-term planning. Also, we quantify the economic significance of lowering wastewater discharges which can be achieved by water recycling or interplant water exchange.

Occurrence, sources and environmental risk assessment of pharmaceuticals in the Sea of Marmara, Turkey.

In the present study, the occurrence and spatial distribution of selected eleven pharmaceuticals were investigated in the Sea of Marmara, Turkey. Samples were collected from different depths of the nine stations in April and October 2019. Pharmaceuticals were analyzed using liquid-liquid and solid-phase extraction (SPE) methods followed by high-performance liquid chromatography (HPLC). All target pharmaceutical compounds were detected at least once in the study area. Gemfibrozil, which belongs to the lipid regulatory group, was the most frequently detected in seawater at high concentrations (<0.016-9.71 µg/L). Ibuprofen (<0.015-2.13 µg/L) and 17α-ethynylestradiol (<0.010-3.55 µg/L) were identified as the other frequently detected pharmaceuticals. In addition, the presence of these selected compounds in April was higher than in October. According to the risk assessment results, naproxen, diclofenac, clofibric acid, gemfibrozil, 17ß-estradiol, and 17α-ethynylestradiol represent a high risk to aquatic organisms in the Sea of Marmara. These findings underline the importance of continued monitoring of these compounds as relevant organic contaminants in the study area to take appropriate measures to protect the ecosystem and, ultimately, human health.

Oxidative decomposition and mineralization of caffeine by advanced oxidation processes: The effect of hybridization.

The study consists of a detailed investigation of the degradability of the emerging water contaminant-caffeine by homogeneous and heterogeneous Advanced Oxidation Processes (AOP's), estimation of a synergy index for each hybrid operation thereof, and proposing the most plausible reaction mechanisms that are consistent with the experimental data. It also encompasses evaluation of the effect of the water matrix represented by carbonate species and humic acids, as strong scavengers of hydroxyl radicals. The results showed that single AOP's such as sonolysis (577 kHz) and photolysis with H2O2 provided complete caffeine elimination, but they were insufficient for the mineralization of the compound. Hybrid AOP's were considerably more effective, particularly when operated at a heterogeneous mode using commercial TiO2. The most effective hybrid process was UV-H2O2/TiO2, which provided more than 75% TOC decay at the minimum test doses of the reagent and catalyst. While the addition of ultrasound to the process significantly increased the rate of caffeine decomposition, it reduced the overall degradation of the compound to 64% in terms of TOC decay. The antagonistic effect was attributed to the formation of excess H2O2, and the presence of cavity clouds and/or high density layers that inhibited the transmission of UV light. The effect of natural water ingredients was found to reduce the reaction rates, signifying the major contribution of hydroxyl radicals to the destruction of caffeine. The proposed reaction mechanisms based on OH radical attack and the calculated energy barriers were in good agreement with the experimentally detected reaction byproducts.

Optimization of methylparaben degradation by sonocatalysis.

Sonocatalytic degradation of methylparaben (MPB) in the presence of a low-cost clay mineral (sepiolite) was optimized using a multivariable center composite design protocol based on response surface methodology (RSM). Using the data generated with varying MPB concentrations, pH, frequency and catalyst dose, two semi-empirical expressions were developed to describe the relation between the apparent reaction rate constant of the parent compound and the most significant control variables. It was found that ultrasonic power, pH, sepiolite dose and its interactions with time and pH were the most significant parameters influencing the rate of MPB decay under high frequency ultrasound. The models also showed that the rate constant was a convex function of time, as it decreased during the first 35-min of sonolysis and increased thereafter, indicating the formation and depletion of competing oxidation byproducts. Finally, the models predicted that the rate of MPB decay was a maximum either at alkaline pH and a high sepiolite dose (k = 1.68 × 10-1 min-1), or at acidic pH and a considerably lower dose of the mineral (k = 1.48 × 10-1 min-1).

Sonochemical and sonocatalytic destruction of methylparaben using raw, modified and SDS-intercalated particles of a natural clay mineral.

The first part of the study is about the degradation of a common PPCP-methylparaben by high-frequency ultrasound to highlight the operation parameters, the reaction sites, the oxidation byproducts and the role of OH radicals. The second part covers the catalytic effect of a highly abundant and cost-effective clay mineral-sepiolite, and investigates the role of surface modification and SDS-composites of the clay in improving the efficiency of the degradation reactions. It was found that the compound (C0 = 10 mg L-1) was readily and totally decomposed by 30-min sonication at neutral pH, producing phenolic and aliphatic intermediates, but with insignificant mineralization. The major reaction site was the bubble-liquid interface, where the reactions were governed by OH radical attack. Modification of the sepiolite surface by pre-sonication in an ultrasonic bath improved the rate of reaction and the degree of TOC decay. Further modification by the synthesis of 20-min sonicated (200 kHz bath) SDS-intercalates of the clay was found to yield significant enhancement in the rate of target compound decomposition and the fraction of TOC decay, provided that the reaction was operated at acidic pH.

Reprint of: Decomposition of PPCPs by ultrasound-assisted advanced Fenton reaction: A case study with salicylic acid.

The study is about the degradation of a widely used pharmaceutical and personal care product-salicylic acid by sonocatalysis, and the experimental design of the reaction system. The first part of the study consists of sonication (572kHz) in the presence of zero-valent iron (ZVI) with or without H2O2 to select and optimize the operational parameters as frequency, time, initial solute concentration, dose of reagents and pH. The second part consists of the use of response surface methodology and multiple regression to develop an experimental design modeland to assess the individual and interactive effects of pH, power (Po), ZVI dose and H2O2. The results showed that the optimal conditions predicted by the model without defining any restrictions are: pH=2.0, Po=120W, ZVI=24mgL-1, which provide total salicyclic acid and 48% TOC decay. However, the prediction implies intensive consumption of energy and reagents, and must therefore be modified by restricting the value of TOC decay to a lower value and that of pH to a higher one. Cross-validation tests showed that the prediction accuracy of the model was considerably high with 5.0-9.4% deviation from the experimental data.

Decomposition of PPCPs by ultrasound-assisted advanced Fenton reaction: A case study with salicylic acid.

The study is about the degradation of a widely used pharmaceutical and personal care product-salicylic acid by sonocatalysis, and the experimental design of the reaction system. The first part of the study consists of sonication (572kHz) in the presence of zero-valent iron (ZVI) with or without H2O2 to select and optimize the operational parameters as frequency, time, initial solute concentration, dose of reagents and pH. The second part consists of the use of response surface methodology and multiple regression to develop an experimental design modeland to assess the individual and interactive effects of pH, power (Po), ZVI dose and H2O2. The results showed that the optimal conditions predicted by the model without defining any restrictions are: pH=2.0, Po=120W, ZVI=24mgL-1, which provide total salicyclic acid and 48% TOC decay. However, the prediction implies intensive consumption of energy and reagents, and must therefore be modified by restricting the value of TOC decay to a lower value and that of pH to a higher one. Cross-validation tests showed that the prediction accuracy of the model was considerably high with 5.0-9.4% deviation from the experimental data.