A radio-frequency plasma system (RF) was used to investigate the removal of microorganisms from water.Plasma generated by RF radiation can produce active compounds (H•, •OH, H2O2, O3, etc.) that have a highoxidation potential and can kill microorganisms present in water (fecal coliforms and total coliforms). Thefrequency of the plasma system was set to 3.0, 3.3 and 3.7 MHz and applied to river water for 60 minutes. Theresults show that in all runs, the pH of the water produced was in the range from 7.4 to 7.9. The removalefficiencies of fecal coliforms achieved were between 83.75 and 95% and were higher than the removalefficiencies of total coliforms, which were between 82.61 and 93.48%. Meanwhile, the death rate (kD) of fecalcoliforms wasfaster than that of total coliforms. Therefore, the removal of total coliforms is the key to removingmicroorganisms fromwater. RF plasma treatment can be used for treatment of drinking water to decreasemicroorganisms.

Phenol adsorption by granular activated carbon from coconut shell was studied in batch experiments under various initial phenol concentrations. Adsorption equilibrium was reached within 4 hours. The characteristics of the phenol adsorption process onto granular activated carbon from coconut shell were studied by adsorption isotherm modeling, analysis that uses fluorescence spectroscopy, in addition to measuring nanoparticle size and volume distribution by a Zetasizer Nano. The Langmuir isotherm model best fits the phenol adsorption onto granular activated carbon from coconut shell, and the maximum adsorption capacities for unsterilized and sterilized types were found to be 17.54 mg/g and 13.70 mg/g, respectively. The excitationemission matrix results showed that the humic-like substance's peaks almost completely disappear post-adsorption. It was also found that the nanoparticle size distribution shifted from ranges of 0.72-1.74 nm in raw water to 45.66-726.73 nm and 57.08-1068.47 nm post-adsorption in unsterilized and sterilized water samples, respectively, suggesting that phenol adsorption had occurred. This study shows that low-cost coconut shell-based activated carbon demonstrated good removal capability and hence can be used as a new adsorbent material on large scale.

Abstract. Onsite application of oxygen supply in domestic wastewater system may be influenced by several factors that can inhibit the oxidation and nitrification processes. In this study, the influence of aeration rate on the Johkasou performance was focused using two Johkasou facilities serving up to five persons household. In the Johkasou A (JO-A) system, we increased the aeration rate from 30 to 63 L.min -1 whereas, in the Johkasou B (JO-B), it was decreased from 59 to 34 L.min -1 . Water and sludge samples were collected from the anaerobic-anoxic-oxic zones before and after adjustment of the aeration rate measured for organic matters and nitrogen parameters. Increasing the aeration rate in JO-A resulted in a high removal of organic matter (82.5%) and nitrogen (60.3%) compared to decreasing of aeration rate in JO-B (52.0% and 33.0%, respectively). Simultaneous nitrification and denitrification (SND) exhibited a maximum percentage when the aeration rate was increased compared to decreasing of aeration rate. These results indicate that application of a high aeration rate increases removal of organic matter and nitrogen and enhances ammonia transformation. It is therefore recommended to apply high aeration rates in Johkasou system.

Inductively coupled plasma system was used in drinking water treatment system to kill the microorganisms in water such as total coliforms (TC), fecal coliforms (FC) and other coliforms (OC) from river water. The aim of this study was to investigate the effect of flowrate on removal efficiency (RE), death rate, and death yield and energy consumption of bacteria's. The frequency of the system was set at 4.6 MHz. The results show that the removal efficiencies and death rate of TC, FC and OC decreased with increasing flowrate. Compared to FC, the first-order reactions of TC and OC were lower in the following order: FC > OC > TC. The death yield of TC and OC significantly increased when the removal efficiency increased. The electromagnetic flux varied from 19.44 to 20.55 W/cm2 and the energy consumption was 0.26, 0.32, and 0.67 with flow rate at 20, 10 and 5 mL/minute, respectively. These results are very necessary to improve drinking water treatment.

The impact of natural organic matter (NOM) and pathogenic bacteria in water are of great concern in water treatment due to their effect on human health. In this study, the ability to combine filtration with an inductively coupled plasma system (ICPS) to remove natural organic matter and pathogenic bacteria from water was investigated. UV260 adsorption, dissolved organic carbon (DOC) and excitation-emission matrices (EEMs) were used to evaluate the removal of NOM by the filtration-ICPS combination. The system was operated at two different flow rates, 100 and 150 ml/minute. Decreasing trend revealed for UV260 and DOC with the higher flow rate. Tryptophan-like substances generally found in water were taken as a measure of microbial activity. This preliminary research shows that the average removal efficiencies for fecal coliforms, total coliforms and salmonella were highest at a flow rate of 100 ml/minute. It can be concluded that the combined filtration-ICPS method is capable of removing NOM and pathogenic bacteria from water.