Identification of Micro-plastics (MPs) in Conventional Tap Water Sourced from Thailand

In a period when MP contamination of drinking water is a great concern, this study focused on the size- and morphology-based count, and polymeric identification of plastic particles in tap water sourced from Thailand. A total of 45 human consumable samples (each 1 L) were collected at Thammasat University. The average MP counts sorted by Nile Red tagging were 56.0±14.0 p/L (6.5-53 µm) and 21.0±7.0 p/L (53-300 µm), while those found by optical microscopic observations were 13.0±5.0 p/L (300-500 µm) and 6.0±3.0 p/L (≥ 500 µm). A significantly high MP amount was observed in the 6.5-53 µm fraction. Fibers dominated in all samples, accounting for 58% of the particle count. Most ≥ 300 µm particles tested by ATR-FT-IR spectroscopy were confirmed to be polymeric, identified as PE, PVC, PET, PA, PTFE, PP, and PAM. These particles may have escaped from the treatment plant or were added along the water distribution network. Since MPs in drinking water constitute a potential health risk by exposing humans to direct plastics intake, MP contamination in water supply systems should be controlled

Identification of Micro-plastic Contamination in Drinking Water Treatment Plants in Phnom Penh, Cambodia

Micro-plastics (MP) contamination in drinking water has become a global concern. Its negative impacts on human health have been reported. This study identified the presence of MP in two different drinking water treatment plants (WTP) in Phnom Penh, Cambodia, and investigated their removal efficiency. Samples were collected from the inlet, sedimentation, sand filtration, and distribution tank to quantify the removal by each unit. An optical microscope and a fluorescence microscope were used to detect the MP in four size fractions: 6.5-20, 20-53, 53-500, and >500 µm. Fourier transform infrared spectroscopy (FT-IR) was used to identify the polymer type for particles with size fractions of 53-500 and >500 µm. The results showed that the MP counted in WTP1 were 1180.5 ± 158 p/L in the inlet and 521 ± 61 p/L in the distribution tank. In WTP2, the MP counted were 1463 ± 126 p/L in the inlet and 617 ± 147 p/L in the distribution tank. The smaller size fraction of 6.5-20 µm predominated at each sampling location. Fragments were the most abundant morphology compared to fibers in all sampling points of both plants. PET predominated and the overall percentages for the inlet tank were 28.8% and 26%, followed by PE with 27.1% and 20.8% in WTP1 and WTP2, respectively. Other common polymer types were PP, PA, PES, and cellophane, while all others accounted for less than 5%. The results of the study showed that a significant number of MP remained in the water distribution system

Microplastics Contamination in a High Population Density Area of the Chao Phraya River, Bangkok

Microplastics (MPs) are distributed globally, including in aquatic environments. While a large number of studies on MPs in marine environments have been performed, few studies are available in freshwater environments. Therefore, the distribution of MPs in surface water and sediment from the Chao Phraya River at Tha Prachan, a high population density area of Bangkok, was investigated. Water samples were collected by a manta trawl with a net mesh size of 300 mm. Sediment samples were collected by a Van Veen grab sampler. The total number and concentration of MPs in the water samples were found to be 104 particles/m3 and 805.20 mg/m3, respectively. The dominant MPs were fragments, 0.5 to 1.0 mm in size, for the water samples. In the sediment, MPs were detected only in a size range of 0.053 to 0.5 mm with a total number and concentration of 2,290 particles/kg and 650 mg/kg, respectively. The presence of different types of MPs was confirmed by Fourier-transform infrared spectroscopy with a dominant abundance of polypropylene, polyethylene, and polystyrene. In brief, this study suggests that high levels of MPs occur not only in the water but also in the sediment of the Chao Phraya River at Tha Prachan area

Activity of Carbon-Based Solid Acid Catalyst Derived from Palm Empty Fruit Bunch for Esterification of Palmitic Acid

The activity of a heterogeneous solid acid catalyst derived from palm empty fruit bunch, synthesized through the direct in-situ H2SO4 impregnation was investigated for the esterification of palmitic acid. The prepared catalyst was characterized by scanning electron microscopy (SEM), Nitrogen adsorption and desorption isotherm, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). It was also analyzed for acid density and elemental composition. The results revealed that the esterification efficiency increases with increasing reaction time, temperature, and methanol loading up to an optimum value. The catalyst showed an excellent activity resulting in >98% esterification efficiency using 5 wt% catalyst, a 6:1 methanol to palmitic acid molar ratio, at 80°C for 5 h in an open reflux reactor, for the reaction conditions. The catalyst was employed in three consecutive runs without considerable loss of the activity. The obtained high catalytic activity is attributed to the high acid density due to the presence of strong (SO3H) and weak (COOH, OH) acid sites in the hydrophobic carbon structure

Humic Acid Degradation by ZnO Photocatalyst

Humic acid (HA) is universally present in soils and natural water resources in a yellow-brown form. HA can react with chlorine during drinking water treatment and produce disinfection byproducts (DBPs), such as trihalomethanes (THMs) and haloacetic acids (HAAs), which are harmful for health. Therefore, HA has to be eliminated from water environment. The photocatalysis is an effective alternative solution for the degradation of HA in a water environment. This research aims to degrade HA from water environment. The rapid degradation of HA, using zinc oxide nanoparticles, irradiated by ultraviolet light (ZnO/UV), is investigated. The optimum conditions of pertinent factors, which include the light wavelength (UV-A and UV-C), and light intensity, HA concentration, ZnO dose, and contact time are investigated at neutral pH conditions, considered for drinking water treatment. HA degradation efficiency reached more than 80% after 60 min for both types of irradiation in optimum conditions of 0.3 g/L ZnO dose in 180 min of contact time. Comparisons for degradation efficiency under UV-A and UV-C irradiation indicate that UV-C has higher efficiency, up to 150 min of contact time. The reusability of catalyst is performed for three reuses and still revealed effective for beneficial commercial applications

Humic Acid Degradation by ZnO Photocatalyst

Humic acid (HA) is universally present in soils and natural water resources in a yellow-brown form. HA can react with chlorine during drinking water treatment and produce disinfection byproducts (DBPs), such as trihalomethanes (THMs) and haloacetic acids (HAAs), which are harmful for health. Therefore, HA has to be eliminated from water environment. The photocatalysis is an effective alternative solution for the degradation of HA in a water environment. This research aims to degrade HA from water environment. The rapid degradation of HA, using zinc oxide nanoparticles, irradiated by ultraviolet light (ZnO/UV), is investigated. The optimum conditions of pertinent factors, which include the light wavelength (UV-A and UV-C), and light intensity, HA concentration, ZnO dose, and contact time are investigated at neutral pH conditions, considered for drinking water treatment. HA degradation efficiency reached more than 80% after 60 min for both types of irradiation in optimum conditions of 0.3 g/L ZnO dose in 180 min of contact time. Comparisons for degradation efficiency under UV-A and UV-C irradiation indicate that UV-C has higher efficiency, up to 150 min of contact time. The reusability of catalyst is performed for three reuses and still revealed effective for beneficial commercial applications

Comparative study of the environmental impacts of used cooking oil valorization options in Thailand

Used cooking oil (UCO) is a valuable resource that can be utilized in different ways. Appropriate management of UCO waste can provide environmental and economic benefits, compared to improper disposal practices. This study assessed the environmental impacts of potential UCO valorization options in Thailand. Altogether, 14 scenarios, including 10 for alternative energy recovering processes (S1-10) and other options such as soap production (S11), use in dry pig feed (DPF) production (S12), synthesis of plastics (S13) and polyol (S14), were considered. The defined system boundaries for each scenario include pretreatment, material and energy consumption, and waste treatment stages for the treatment of 1000 kg UCO. Environmental impacts in terms of global warming potential (GWP), freshwater eutrophication potential (FEP), fossil resource scarcity (FRS), and freshwater, terrestrial, and marine eco-toxicity (FE, TE, and ME, respectively) were analyzed using the ReCiPe Midpoint (H) method. The results revealed that all the current waste valorization options create an environmental burden and contribute towards GWP. Scenarios 7 and 10 showed environmental credits for FEP, FE, and ME indicators while scenario 9 did so for FRS. The processes direct energy consumption resulted in the highest contribution to GWP in Scenarios 1, 5–8, 10, 12, and 13. Environmental effects of material consumption and waste treatments were found to be the highest in bio-oil and DPF production, respectively. However, co-products produced could not offset the burden created by energy and material consumption. Overall, the results showed better environmental performance from energy recovery-based UCO management options compared to alternative processes

Sustainable Utilization of Sewage Sludge through the Synthesis of Liquid Fertilizer

In a world with a growing human population, resources are becoming increasingly scarce. To ensure food supply, fertilizers are often used to accelerate growth when planting agricultural products. Sewage sludge (SS), containing as high as 10–15 wt% Phosphorus (P), can be synthesized into liquid fertilizer. P species in SS can generally be classified into four types: inorganic phosphorus (IP), organic phosphorus (OP), nonapatite inorganic phosphorus (NAIP), and apatite phosphorus (AP). However, OP is not leached out by wet chemical methods and NAIP is not bioavailable. This study investigated the P-form conversion (OP and NAIP to AP) in SS by adding 8 wt% CaO at 300 °C. SS through pretreatment can easily leach out P when combined with organic acid. The content of heavy metals is in accordance with fertilizer regulations in a leaching solution. The solution was mixed with potassium and ammonia compounds to synthesize a liquid fertilizer. To ensure the safe and efficient use of liquid fertilizer and undertake an analysis of heavy metals, an aquatic organisms (D. magna) toxicity test, and the growth of plants test were both used. The liquid fertilizer can be demonstrated to accelerate the growth of plants while not causing the death of D. magna in short time, as the liquid fertilizer has enough nutrients to help the D. magna to survive

Challenges and opportunities to approach zero waste for municipal solid waste management in Ho Chi Minh City

Ho Chi Minh City (HCMC) is a mega city with a total population of more than ten million. The quantity of solid waste generated has been increasing significantly over the past two decades, and the average generated solid waste was 1,164 tonnes/day in 1992 and 8,845 tonnes/day in 2017. Municipal solid waste (MSW) management has been considered as one of the most severe environmental problems as the quantity of solid waste has increased while infrastructure for collection and treatment is not sufficient. The paper focuses on evaluating challenges and suggesting opportunities for reducing the amount of waste disposal in landfills through interception and separation of the waste at source. After the waste separation, the biodegradable organic materials and recyclable materials from MSW can be collected for further use. Based on the current situation of MSW management, technologies such as composting, biogas recovery and electricity generation either from anaerobic digestion plants or sanitary landfills are appropriate. Incineration for high calorific value waste can be adopted for energy recovery. Effective recycling technologies to convert waste into valuable products seem to be a solution for approaching zero waste for MSW management in HCMC