Microplastic pollution has been widely studied as a global issue due to increased plastic usage and its effect on human and aquatic life. Microplastics originate from domestic and industrial activities. Wastewater treatment plants (WWTPs) play an important role in removing a significant amount of microplastics; otherwise, they end up in bioaccumulation. This study provides knowledge about the characteristics of microplastics, removal efficiency, and the correlation between wastewater quality and microplastic concentrations from three different WWTPs that differ in the type of biological and advanced wastewater treatment techniques that are believed to play an important role in microplastic removal. Microplastics of different types, such as fragments, fibers, and beads, are identified by using an optical microscope before and after the treatment process at each stage to assess the effect of different treatment techniques. In the screening unit and primary clarifier unit, WWTP-B shows the highest removal efficiency with 74.76% due to a distribution flow system installed before the primary clarifier to ensure a constant flow of wastewater. WWTP-B uses a bioreactor consisting of a filter plate coated with activated carbon (BSTS II) that can enhance the adaptability and adhesion of microorganisms and showed that 91.04% of the microplastic was removed. Furthermore, only WWTP-A and WWTP-B were applied coagulation, followed by the disc filter; they showed significant results in microplastic removal, compared to WWTP-C, which only used a disc filter. In conclusion, from all WWTP, WWTP-B shows good treatment series for removing microplastic in wastewater; however, WWTP-B showed a high rate of microplastic removal; unfortunately, large amounts of microplastics are still released into rivers.

In response to the finding of chironomid larvae in tap water, South Korea’s water treatment system has stepped up water quality monitoring. However, due to the challenging nature of larval behavior, effective elimination remains difficult despite the use of various purification techniques such as coagulation, sedimentation, filtration, and disinfection. Based on it, the aim of this study is to evaluate the effectiveness of coagulation and chlorination in inactivating chironomid larvae and investigate their behavior. The coagulation experiment tested how the behavior of the larvae changed in water with a high turbidity level of ±100 mg/L and 2 mg/L Al³⁺ as a coagulant, compared to water with a lower turbidity level of ±30 mg/L and 1 mg/L of Al³⁺ as a coagulant. The larvae were exposed to various doses of chlorine (0.5–20 mg/L as Cl) in 500 mL beaker glasses. The behavioral activity of the larvae was observed at different time points for 5 days. It was found that chironomid larvae exhibit different responses to exposure to coagulant and chlorine, with coagulation causing the formation of flocs that cover the larval body as a protective measure. Conversely, exposure to chlorine causes a decrease in activity and growth, leading to the death of the larvae and subsequent melting. The results showed that the first instar larvae dead after 48 h of exposure to coagulation treatment, while the first instar larvae exposed to chlorination experienced mortality after a mere 5 min of exposure to 10–20 mg/L as Cl. The larvae can still grow and transform into pupae and adults, especially during the third and fourth instars, even after exposure to coagulant and chlorine with low dosage. These findings suggest that the floc generated during coagulation must be thoroughly cleaned, as it may contain larvae that can persist and develop further. Furthermore, the presence of larvae during the chlorination process highlights the need for alternative, more effective oxidants to be utilized in place of the conventional chlorine treatment.

The presence of invertebrates in drinking water distribution systems, particularly Chironomidae larvae, has raised concerns among the general public. This study aimed to comprehensively address the issue of larvae breakout in water filtration systems and provide potential solutions to prevent their escape into the water supply. The research investigated various factors contributing to larvae breakout, including the type of filtration column, sand depth, pretreatment methods, and the effective size and uniformity coefficient of sand media. Experimental results revealed that the GAC column, primarily utilized for adsorption, was ineffective in retaining Chironomidae larvae, leading to their escape within a short period. Similarly, the sand filter column, with a design that is currently widely used with sand specifications of an effective size of 0.7 mm and a uniformity coefficient of 1.7, failed to act as a barrier for larvae. Increasing the height of the sand media and applying a pretreatment method, which was expected to prevent larvae from entering the treated water, yielded unsatisfactory results. Our research results show that reducing the uniformity coefficient to 1.5 while maintaining an effective size of 0.7 mm proved to be important in preventing the release of larvae into treated water. The Sand/GAC and Sand/Anthracite systems, by maintaining adjusted media sand specifications, also succeeded in retaining larvae in the filtration system. Additionally, this study emphasized the importance of following the recommended backwash procedure, consisting of specific steps involving air flow, a combination of air and water flow, and final water flow. This sequence effectively removed contaminants, turbidity, and Chironomidae larvae from the filtration media, ensuring improved water quality and system performance. The findings of this study provide valuable insights and recommendations for water treatment plants to address the issue of larvae breakout and enhance water quality.

Environmental pollution caused by unmanaged scrap battery smelting activities in Cinangka and Cinangneng villages, Bogor Regency, has led to heavy metal contamination, particularly lead (Pb), which threatens public health and the ecosystem. This study employs the Analytical Hierarchy Process (AHP) to evaluate four contaminated land remediation methods encapsulation, on-site stabilization and solidification, phytoremediation, and dig and fill based on legal, technical, financial, and environmental aspects. The analysis results indicate that the dig-and-fill method is the best solution for addressing contamination at priority sites with high pollution levels and proximity to residential areas. This method effectively removes contaminated soil and replaces it with pollutant-free soil, thereby minimizing health risks. This study provides strategic recommendations to support land remediation policies in Bogor Regency.