Tongchai Sriwiriyarat

Simultaneous removal of ammonium (NH4+), nitrate (NO3–), nitrite (NO2–), and phosphate (PO43–) from secondary effluent remains challenging in advanced wastewater treatment. Biochar-reinforced natural rubber latex foam (NRLF) composites were fabricated via the Dunlop process as structured, particle-retaining adsorbents for multicomponent nutrient removal. Among formulations tested (0–8 phr biochar), the NR–B2 composite (2 phr biochar) achieved the most balanced simultaneous removal under optimal conditions (pH 7, 10 g·L–1, 28 °C), with PO43– removal reaching 92.58%. The pH-responsive, charge-switchable surface (pHpzc = 7.3) enabled concurrent cationic and anionic uptake within a single monolithic framework. Model fitting revealed maximum adsorption capacities (qm) of 5.50, 20.62, 1.27, and 0.03 mg·g–1 for NH4+, PO43–, NO3–, and NO2–, respectively. Equilibrium was reached between 4 and 12 h depending on the specific ion. NH4+ followed pseudo-first-order kinetics and Langmuir isotherm behavior, while anionic species conformed to pseudo-second-order kinetics and Temkin isotherm behavior. Furthermore, thermodynamic evaluations indicated that the adsorption processes were spontaneous (ΔG° < 0) and endothermic (ΔH° > 0), consistent with predominantly weak-to-moderate adsorption interactions under the investigated conditions. Postadsorption BET, ATR-FTIR, and XPS analyses confirmed phosphorus-containing surface species and preserved structural integrity following nutrient uptake. The NR–B2 composite requires no chemical modification, eliminates biochar particle loss, and is directly applicable as a structured adsorptive medium for tertiary nutrient polishing.

Molecularly imprinted materials based on imprinting dithizone‐Zn (II) (DTZ‐Zn (II)) complexes onto cotton fabric/silica, and the Color Grab application for the OPPO A54 smartphone, were proposed and applied for the first time to detect Zn (II) ions in water samples. The proposed materials were prepared by using cotton fabrics as cellulosic materials, tetraethoxysilane as silica sources and DTZ‐Zn (II) as template molecules. The initial concentration of DTZ and Zn (II), the volume of tetraethoxysilane and the reaction time were optimised to obtain the maximum adsorption of the DTZ‐Zn (II) complexes in the imprinted materials. The concentration of hydrochloric acid and the extraction time were optimised to obtain the maximum Zn (II) removal. The results found that 10 mL of a solution containing DTZ (0.20 mM) and Zn (II) (0.30 mM), 25 μL of tetraethoxysilane, with 10 minutes reaction time, exhibited the strongest binding of the template complexes. Zn (II) ions were selectively removed from the materials by using 0.1 M hydrochloric acid for 10 minutes. The morphology of the prepared materials was characterised by scanning electron microscopy–energy‐dispersive X‐ray spectroscopy and attenuated total reflectance–Fourier Transform‐infrared spectroscopy. The smartphone measurement based the cotton fabric/silica materials exhibited linear relationship between saturation (%) and Zn (II) concentrations in the range of 0.1 to 1.0 mg/L, with limit of detection of 0.02 mg/L and limit of quantification of 0.06 mg/L. The proposed method was successfully applied to determine Zn (II) in real‐water samples with the % recovery ranging from 98% to 115% and an acceptable relative standard deviation of less than 6 (n = 3).

Metal contamination from farming, inadequate wastewater treatment, and poor disposal of municipal garbage are major threats to public health. This research aimed to (1) assess the extent of heavy metal contamination in sediment samples, (2) describe the distribution of heavy metals by locating likely pollution sources using a positive matrix factorization (PMF) model, and (3) quantify the potential ecological consequences associated with these metals at six different places around the Chan Thnal Reservoir. The findings indicated steady degradation and suggested moderate to high metal contamination. Fe > Zn > Cr > Cu > Pb > Co > As > Mn > Cd was the trend of metal concentrations in the sediment. Various soil pollution indices showed that most of the studied sediment samples were clean, moderately clean, or slightly contaminated. However, Co and Cd reached high-risk conditions posing a severe problem to the local population living in and around the Chan Thnal Reservoir. Principal component analysis (PCA) was used to estimate primary factors in PMF analysis. It was found that the contamination of As, Cu, Zn, Cd, and Pb originated from agricultural and traffic vehicle sources; however, Zn, Fe, Mn, Cr, and Cu were derived from natural sources (e.g., atmospheric deposition and compost amendment). Furthermore, Fe, Cd, Mn, Co, Pb, and Cr were generated from urban and industrial sources (metal coatings, plastic burning, wastewater irrigation, and sewage sludge). Accordingly, this research improves our knowledge of the prevalence of heavy metal pollution in agroecosystems, which may be used to foresee and mitigate the risks of heavy metal exposure to humans and other organisms.

Chan Thnal reservoir, built during the Pol Pot period, is the major water source for the people in Krang Chek commune, Kampong Speu Province, Cambodia. Metal pollution caused by agricultural activities, improper wastewater treatment, and municipal waste disposal poses serious environmental health problems. In this study, the concentrations of four potential toxic metals (i.e., Cd, Cu, Pb, and Zn) from six locations across the reservoir were investigated both in the water and sediment. The results reflected progressive deterioration and indicated moderate to heavy pollution from the metals. The metal levels in the water were in the order of Zn > Cu > Pb > Cd. The statistical analysis revealed primary sources of heavy metals contamination in the water. Cd, Cu, Zn, and Pb in the water likely originate from anthropogenic activities including agricultural runoff (i.e., the use of fertilizers and pesticides) and urban runoff (i.e., improper wastewater discharge and waste disposal). Among the four metals, the Pb levels in the water significantly exceeded the guideline for drinking water in all locations. The health risk assessment revealed serious non-carcinogenic risks of Pb intake in the children at the age below 10 and infants. Appropriate control and protection strategies are urgently needed to cut off the main Pb exposure pathway in pregnant women, children, and infants.

The acute effects of acrylamide and its biodegradation products on the respiration activities of microbes during wastewater treatment are not well understood. Herein, unacclimatized mixed culture bacteria and Enterobacter aerogenes from two aerobic treatment systems, Activated Sludge (AS) and Integrated Fixed Film Activated Sludge (IFAS) both of which were sequencing batch reactors (SBR), were studied for their response to acrylamide. Respiration activities and biodegradation rates were determined by both the OxiTop respirometer and batch studies. The experimental results revealed that E. aerogenes in the AS system quickly removed both acrylamide and acrylic acid without the need of an acclimation period, but required two hours for removing acrylic acid in the IFAS system. The mixed culture bacteria in both AS and IFAS systems required 2 hours to acclimatize with acrylamide and 1 hour for acrylic acid, respectively. Acrylic acid was initially polymerized to produce acrylic acid polymer or reacted with ammonia to form acrylamide, resulting in the reduced acrylamide biodegradation rate. Both E. aerogenes and mixed culture bacteria from the AS systems could simultaneously biodegrade acrylamide and acrylic acid whereas only acrylamide was biodegraded by both cultures in the IFAS systems due to the limitation of acrylic acid diffusion. The results also indicated that ammonia inhibited the acrylamide biodegradation by both E. aerogenes and mixed culture bacteria from the AS systems. The unacclimatized E. aerogenes and mixed culture bacteria from the AS systems showed superior performances compared to the ones from the IFAS systems.