Domestic wastewater containing a high proportion of organic matter and nutrients is a serious pollution problem in developing countries. This study aimed to evaluate the performance of a novel attached-growth high rate algal pond (AG-HRAP) employing attached-growth media and artificial light sources for treating domestic wastewater and enhancing nutrient recovery. Light intensities in the range of 40–180 μmol/m2/s were used in the AG-HRAPs. The experimental results showed that the highest chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) removal efficiencies of 88, 62 and 69%, respectively, were found at the hydraulic retention time (HRT) of 15 days and the average light intensity of 180 μmol/m2/s. Moreover, the effluent COD concentrations could meet Thailand's national discharge standard. The highest biomass and protein productivities of 54 ± 4 and 37 ± 8 g/m2/d, respectively, were found in the AG-HRAPs, which were higher than in previous studies of HRAPs. The Stover-Kincannon kinetic values for COD, TN and TP removals of the AG-HRAPs (R2 = 0.9) were higher than those of the conventional systems. Additionally, the novel AG-HRAP system could provide a highly cost-effective operation when compared to other microalgal systems.

The growing population with changing consumption patterns in developing countries is causing significant challenges with regards to solid waste management. Plastic wastes are particularly problematic, with single-use plastics leaking into the environment, including the marine environment, at an unprecedented rate. Approximately 80 percent of ocean plastics come from land-based sources or about 8 million tons are dumped into the ocean every year. Thailand was identified as one of the top 10 countries ranked by mass of mismanaged plastic wastes, with more than 60,000 tons per year entering the ocean through multiple outlets, including rivers. In the environment, plastic wastes can be degraded into small sizes (less than 5 mm), called microplastics (MPs), which could contaminate the ecosystems and the food chain, including foodstuffs and water supply. Tap water samples collected from a water supply treatment plant and Academic Institutions 1 and 2 in central Thailand were found to contain MPs about 304 ±90, 270 ±109 and 386 ±102 particles/L, respectively. In addition, MPs concentrations of 211 ±70 and 122 ±60 particles/L were also found in drinking water samples collected from commercial bottled water and membrane filtration water, respectively. The MPs sizes of 0-50 µm were most abundant in both the tap and drinking water samples whose shapes were mainly fragments and fiber. These data indicated potential health risks to the people who consume these water sources, and recommendations for health impacts minimization were proposed.