Microplastic (MP) contamination in aquatic environments is a critical concern due to its potential effects on aquatic ecosystems. MP contamination is often unsatisfactorily eliminated using conventional wastewater treatment systems. Membrane bioreactor (MBR) is a modern solution for wastewater treatment offering significant advantages over traditional activated sludge systems, such as a smaller footprint and the ability to produce high-quality effluent. In this study, a pilot-scale MBR was conducted to evaluate MP removal from real greywater. The overall treatment performance for MP removal reached up to 90%, with the MP concentration in the permeate effluent being 0.02 MP L⁻¹. The major MP size distribution was 101–300 μm, with polypropylene as the predominant MP type. Remarkably, polyester fibers were highly predominant in the suspended sludge. Furthermore, Alphaproteobacteria, Bacteroidetes, and Actinobacteria were the predominant communities in the MBR sludge, which preferably formed a biofilm associated with MP accumulation. This study underscores the potential of MBR technology for efficient MP removal in household buildings, contributing to the mitigation of MP discharge into the environment. Implementing MBR systems is a crucial step toward safeguarding aquatic ecosystems and preserving environmental integrity with respect to the corresponding increase in MP pollution.

The effect of non-thermal air plasma on green oak lettuce farming has been proposed. A gliding arc plasma generator (GAPG) was designed for plasma-activated water (PAW) spray generation. A PAW spray was generated at 8, 10, and 12 kV by a custom-made ac high voltage power supply. Four hydroponic green oak lettuce trays were treated by PAW spray at different conditions for 10 min, three times a day for nine days. The experimental results showed that all the plasma-treated green oak lettuce sprouts had a greater growth rate than the control group. The best condition was found in the PAW spray generated at 8 kV source voltage, which led to the longest average height and width of sprouts of 10.88 ± 0.33 cm and 10.09 ± 0.08 cm, respectively. Moreover, its average dried weight was also significantly greater than that of the control group by 1.69 times. It was found that the concentration of total Kjeldahl nitrogen (TKN), mainly ammonium, was enhanced in every PAW spray condition. However, the highest TKN concentration was found in the 8 kV PAW spray, which was 3.67 times higher than that of the control group. The amount of nitrite (NO ₂ ⁻ ) and nitrate (NO ₃ ⁻ ) in PAW spray was also enhanced but in the opposite trend to TKN concentration. Moreover, the electrical conductivity (EC) and pH levels could be improved by air plasma. It could be confirmed that the plasma treatment could be effectively applied to green oak lettuce farming, and the PAW spray generated by the GAPG could enhance the amount of nitrogenous fertilizer in treated water, which is essential for plant growth stimulation.

The influence of plasma-activated water (PAW) as a liquid nitrate–nitrogen (NO $_{3}$ –N) fertilizer on microalgae cultivation has been studied in this research. A helical-electrode gliding arc plasma generator (HGPG) has been proposed for practical use in a circulating PAW generation system. The arcing gap ( $A_{\text{G}}$ ) between HGPG electrodes and treatment time has played a significant role in increasing electrical conductivity (EC), hydrogen peroxide, NO $_{3}$ –N concentration, and oxidation–reduction potential (ORP) of PAW contrasting to the pH, which has the opposite trend. At the 0.25-cm $A_{\text{G}}$ and 45-min treatment time with a 15-kV, 125-W commercial neon power supply, EC, ORP, and NO $_{3}$ –N concentrations of PAW are 3.40, 2.0, and 12.30 times higher than that of the control group, respectively. The pH has dropped from 7.45 $\pm$ 0.04 to 3.74 $\pm$ 0.02. Regarding the experimental result of applying PAW in microalgae farming, it could be confirmed that the PAW generated by HGPG could be used as a potential nitrogen compound fertilizer for microalgae cultivation. The highest specific growth rates ( $\mu $ ) of microalgae from the setup mentioned earlier conditions are 1.117 times higher than that of the control group.