Analysis of wastewater reuse options using a multicriteria decision tool for Phuket, Thailand.

The act of balancing between water demand and water supply in Phuket Island is facing challenges, suggesting water reuse options in various activities on the island should be properly promoted considering the potential benefits in a variety of dimensions. This research presented options to reuse effluent water from wastewater treatment plants for Phuket Municipality in 3 main activity groups, namely, domestic reuse, agricultural reuse, and raw water for water treatment plants (WTP). Water demand, additional water treatment trains, and the length of the major water distribution pipeline for each water reuse option were designed, and its cost and expenses were calculated. Multi-criteria decision analysis (MCDA) was used by 1000Minds internet-based software to prioritize the suitability of each water reuse option based on a four-dimensional scorecard, including economic, social, health, and environmental aspects. The decision algorithm for the trade-off scenario based on the government's budget allocation was proposed to obtain weighing without subjective expert opinions. The results revealed that recycling effluent water as raw water for the existing WTP was the first priority, followed by agriculture reuse for planting coconut, Phuket's economic crops, and domestic reuse. There was a significant difference in the total scores of economic and health indicators between the first- and second-priority options because of the difference in the additional treatment system in which the first-priority option applied the microfiltration and reverse osmosis system, which could effectively eliminate viruses and chemical micropollutants. In addition, the first priority option required a much smaller piping system than other water reuse options because it relied on the existing plumbing system of WTP, lowering the investment cost, which was a very important indicator for decision-making.

Wastewater reclamation trends in Thailand.

Thailand constantly faces the problem of water scarcity, resulting from an imbalance between available water supply and increasing water demand for economic and community expansion, as well as climate change. To address this shortage, wastewater reclamation is being planned and implemented throughout the country, along with a 20-year, long-term integrated water resource management plan. Significant opportunities from municipal wastewater treatment plants (WWTPs) are dependent on the following factors: the establishment of a reuse water framework and a tangible target for treated wastewater set by local government authorities; widespread recognition and adaptation of wastewater reuse measures in the agriculture, industry, tourism and service sectors regarding climate change and water stress; and the implementation of joint investment water reuse projects between private and government agencies. However, wastewater reclamation faces some significant challenges, specifically: the limitations of regulation and monitoring for specific reuse purposes; a lack of public confidence in the water quality; the limited commercial development of reclaimed wastewater research; and difficulties in self-sustaining business models through adapting circular economy principles. This study aims to provide an overview of the wastewater reclamation, present research trends, currently operating WWTPs as well as opportunities and challenges to speed up water reuse activities in Thailand.

Assessment of the economic recycling potential of a glycolysis treatment of rigid polyurethane foam waste: A case study from Thailand.

This research assessed the economic feasibility of recovering polyol from rigid polyurethane foam (RPUF) waste, collected from dismantled, discarded refrigerators, by a single-phase glycolysis recycling process using domestic crude glycerol (a byproduct of biodiesel production) as a transesterification agent. The study, conducted in Thailand, took into account benefits from the added value of the recovered product, the investment and related operating costs of the process, demand (the need for the recovered product) and supply (the amount of RPUF waste). The results showed that the production of recovered polyol from RPUF waste is economically feasible, with a net present value of 1,113,018 USD, an internal rate of return (IRR) of 22.9%, and a payback period of 4.4 years. Due to the high IRR, project investment should be attractive to both the government and private sector investors. In addition, a sensitivity analysis was conducted to assess the economic resilience of the process to uncertainties in key factors, including the prices of the machinery, recovered polyol, crude glycerol and stannous octoate, and the amount of RPUF waste available. The sensitivity analysis showed that the economic feasibility was most sensitive to the price of the recovered polyol, followed by the amount of RPUF waste and the prices of the machinery, crude glycerol and stannous octoate. Based on these results, technological, operational, financial, and regulatory policy recommendations were also presented.

Characteristics of slag, fly ash and deposited particles during melting of dewatered sewage sludge in a pilot plant.

This study examines slag, fly ash, and deposited particles during melting of dewatered sewage sludge in a pilot plant. In addition, the chemical composition of particles in flue gas was simulated using a thermodynamics program, namely FACTSage 5.2. The results showed that the main components of slag were Al, Fe, Ca, P and Si; the minor components were Na, K, Mg, Cu, and Zn. The main chemical compound of slag was Ca4(Mg,Fe)5(PO4)6. For fly ash particles, heavy metals with the highest concentrations were in the order of Zn and As, Pb, Cu, and Cd, respectively. For non-heavy metals, Al, Fe and P were also found in significant amounts. The majority of deposited particles were composed of elements of Zn, P, S, Na, Fe, Al, Si, and Ca and such chemical compounds as Zn3(PO4)2, AlPO4, FePO4 and Fe(OH)3 while the minority consisted of elements of As, Cu, and Pb. Moreover, the compositions of deposited particles in each chamber differed due to different flue gas temperatures inside. In the secondary chamber at 760 degrees C, the amounts of Fe and Al were higher than Zn, whereas, in the other chambers (600-400 degrees C), the amount of Zn was higher. In other words, at the lower temperature the deposition of Zn was higher than the deposition of Fe and Al. In the water cooling section, volatile elements (i.e. Zn, As, Cu, Pb) were found in the highest concentrations due to a big difference in temperature between the wall surface and flue gas. From the simulation results, most of the elements in the gas phase were found to be chloride compounds, whereas those in the solid phase were in the form of oxide, sulfate, and phosphate compounds.