Characteristics and seasonal variation of microplastics in the wastewater treatment plant: The case of Bursa deep sea discharge.

Microplastics (MPs) are an emerging pollutant that can be detected in all ecosystems, especially aquatic ecosystems. Wastewater treatment plants (WWTPs) are important point sources of MP release into the sea. In this study, the characteristics of MPs in wastewater and sludge samples taken from different units of WWTP in Bursa-Gemlik district for 12 months were investigated. Wastewater and sludge samples collected from 7 different points were classified as size, shape, color, and counted. The amount of MP in the influent and effluent of the WWTP, respectively; 107.1 ± 40.2 MP/L and 4.1 ± 1.1 MP/L. Although the MP removal efficiency of the WWTP is 96.17 %, approximately 74,825,000 MP is discharged into the Marmara Sea every day. The amount of MP in the sludge is 14.3 ± 7.1 MP/g. The amount of MP accumulated in 22tons of waste sludge formed daily in WWTP was calculated as 314,600,000 MP, and the annual accumulated amount was calculated as approximately 1.15 × 1011 MP. The MPs in the WWTP were mainly 1-0.5 mm in size. Fibers were the dominant MP shape in both the wastewater and sludge samples. Black and transparent were the dominant MP colors. Seven different polymer types of MPs were detected, which were mainly types of polyethylene, polypropylene, and polyethylene terephthalate. Despite the high removal efficiency in the investigated WWTP, it has been shown that it acts as an important source of MPs to the sea ecosystem due to the high discharge rates.

Abundance and characteristics of microplastics in an urban wastewater treatment plant in Turkey.

Wastewater treatment plants (WWTPs) are considered one of the important sources of aquatic/terrestrial microplastic (MP) pollution. Therefore, the abundance and properties of MPs in the wastewater and sludge of an urban WWTP in Bursa Turkey were investigated. The amount, properties, and removal of MPs were evaluated. The results showed that the average abundance of MPs was 135.3 ± 28.0 n/L in the influent and 8.5 ± 4.7 n/L in the effluent, with a 93.7% removal rate, MP was removed and transferred to the sludge. The daily MP amount released in the aquatic environment is calculated as 525 million MPs, and the annual amount is 1.9 × 1011 MPs. The abundance of MPs in the sludge thickening and sludge filter cake is 17.9 ± 2.3 and 9.5 ± 2.3 n/g dry weight (dw), respectively. The sludge disposal amount of WWTP is 81.5 tons/day and the approximate amount of MP accumulated in the sludge per year is calculated as 2.8 × 1011 MPs. In wastewater and sludge samples, fragment dominant shape, black main colour, and 500-1000 µm sizes are the most common size. The main MP types in wastewater samples at the influent are polypropylene (PP, 36.8%), polyethylene (PE, 31.0%), polystyrene (PS, 11.8%), polyethylene terephthalate (PET, 8.0%), and polyamide (PA, 7.1%), at the effluent (PE, 33.0%), (PP, 52.5%), and (PS, 8.2%). In the sludge cake, the distribution is (PE, 40.8%), (PP, 27.6%), (PS, 18.7%) and (PET, 8.0%). The results of this study show that MPs are removed from wastewater with high efficiency by treatment processes and a significant amount accumulates in the sludge. Therefore, it is suggested that to integrate advanced treatment processes into urban WWTPs and use effective sludge disposal management practices to reduce the amount of MP released into the environment with effluent and sludge.

Monitoring and evaluation of the efficiency of a mixed textile-domestic wastewater treatment plant for 3 years.

In this study, the performance of the wastewater treatment plant, which treats approximately 80,000 m3/day of domestic and industrial wastewater in the Bursa, Turkey, for the 2018-2020 period, is evaluated based on the analysis of chemical oxygen demand (COD), biochemical oxygen demand (BOD), suspended solid (SS), total nitrogen (TN), total phosphorus (TP), color, and some heavy metals (Cr+6, CN-, Cd, Fe, Cu, and Zn) parameters. Treatment plant removal efficiencies were 61-91% for COD; 78-97% for BOD; 54-94% for SS; and 57-84% for TN. It was detected in the range of 23-84% for TP and 40-68% for color. The operating costs per treated wastewater volume were calculated as 0.0675 USD/m3 and 2.94 USD/kg COD per organic load removed. The quality of treated water was compared with the discharge limits of the receiving medium, and no limit values were exceeded in any parameters during the monitoring years.

Advanced oxidation and mineralization of 3-indole butyric acid (IBA) by Fenton and Fenton-like processes.

The degradation and mineralization of 3-indole butyric acid (IBA) in aqueous solution was examined using Fenton and Fenton-like processes. Various operating conditions were evaluated including pH and the concentrations of iron ions (Fe(2+) and Fe(3+)) and hydrogen peroxide (H(2)O(2)). The highest COD removal efficiency was achieved at 0.2 mM/0.6 mM Fe(2+)/H(2)O(2) ratio and 0.2 mM/1.0 mM Fe(3+)/H(2)O(2) ratio at pH 3 for Fenton and Fenton-like processes, respectively. IBA degradation and mineralization exhibited pseudo-first-order kinetics while the depletion of H(2)O(2) and Fe(2+) or Fe(3+) exhibited zero-order kinetics during both processes in all experiments. 97% of IBA degradation proceeded via two distinctive kinetic regimes. The initial phase of the reaction was directly attributable to the Fenton reaction wherein nearly all of the OH radicals were generated. This was followed by a slower degradation phase, which can be thought of as a series of Fenton-like reactions within a Fenton process. In the Fenton-like process, the initial phase lasted longer than in the Fenton process because the generation of OH radicals proceeded at slower rate; however, 98% degradation of IBA was achieved. The mineralization of IBA was 16.2% and 50% for Fenton and Fenton-like processes, respectively. After 24 h, H(2)O(2) was the limiting reagent for further mineralization of IBA intermediates present in the system. The results of the study showed that Fenton Process may be more useful when only removal of IBA is required and mineralization is unnecessary. But if mineralization of IBA is needed, Fenton-like process gains more important than Fenton Process due to its mineralization efficiency.

Occurrence and removal of metals in urban wastewater treatment plants.

In this study, nine metals (Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) found in urban wastewater treatment plants (WTPs) in Bursa (Turkey) were monitored for 23 months in 2002 and 2007. Metal influent and effluent concentrations of wastewater stabilization ponds (WSPs) and the activated sludge process (ASP) measured via 24-h composite samples were used to determine removal efficiencies. Average influent concentrations ranged between 2 microg/L (Cd) and 1975 microg/L (Fe). In the stabilization ponds, the removal efficiency was 58% for Cr, while for Cd, Mn, and Pb, it was less than 20%. The activated sludge process yielded high removal efficiencies, ranging from 47% for Ni to 95% for Cr. The use of treated wastewaters for agricultural purposes was investigated, and it was determined that all metal concentrations met application limits, with the exception of Cr in wastewater stabilization pond effluent. Results showed that wastewater stabilization pond effluent reduced the receiving water quality with respect to Cr, Cu, Ni, and Pb. In addition, it was shown that effluent from the activated sludge process temporarily improved the receiving water quality with regard to the Cd, Cu, Mn, and Zn parameters. However, considering the periodic variations of the metals in both processes, water quality, and agricultural practices, it was determined that they should be monitored continuously.