Salah satu indikator air minum yang digunakan aman untuk kesehatan adalah kandungan mikrobiologi.. Air minum yang aman adalah kandungan mikrobiologinya 0 koloni/ 100ml. Adanya mikrobiologi pada air minum menunjukkan bahwa dalam satu atau lebih tahap pengolahan air minum pernah mengalami kontak dengan cemaran yang mengandung mikrobiologi. Disinfeksi merupakan metoda untuk membunuh mikrobiologi yang terkandung dalam air minum. Penelitian ini dilakukan untuk membandingkan hasil disinfeksi menggunakan ozon dengan sinar ultraviolet terhadap kandungan mikrobiologi pada air minum isi ulang. Metode penelitian yang dilakukan adalah metode penelitian observasional. Parameter yang diamati adalah suhu, pH dan total mikrobiologi. Hasil penelitian menunjukkan bahwa pH menunjukkan terjadi penurunan dari hari ke hari, hal ini disebabkan karena reaksi kimia dan aktivitas mikrobiologi.TPC pada proses disinfeks menggunakan ozon diketahui bahwa nilai TPC yang terkecil yaitu 1 koloni/100 ml pada hari kedua, hal ini disebabkan reaksi ozon dalam air dimana H2O2 dan (OH*) merupakan oksidator yang sangat kuat baru bekerja optimal pada hari kedua kemudian akan meningkat sampai 13 koloni / 100 ml pada hari ke 5. TPC pada proses disinfeksi menggunakan sinar UV pada hari pertama nilai TPC paling kecil yaitu 1 koloni/100 ml tetapi pada hari berikutnya TPC cenderung meningkat sampai 18 koloni/ 100 ml pada hari ke 5.

One indicator of safe drinking water is its microbiological content of 0 colonies/100 ml. Ozonation is one method for killing microbes contained in drinking water. Disinfection in refillable drinking water that uses ozone needs to be studied, considering that the drinking water put into used gallons is washed again and can be drunk directly by consumers. It should be suspected that the drinking water used from drinking refill water contains bacteria, a dangerous virus. So the purpose of this study is to find out the microbiological content in refill drinking water with variable storage time for refill drinking water. The research method used is an observational research method. The parameters observed were temperature, pH, total microbes and dissolved oxygen content where the dissolved oxygen content indirectly indicates the reaction process of ozonation and bacterial activity contained in refill drinking water. The results showed that at pH showed a decrease from day to day, things this is caused by chemical reactions and microbiological activities. TPC shows that the smallest TPC value is 1 colony/100 ml on the second day, this is due to the ozone reaction in the water here H2O2 and (OH *) are very strong oxidizers which work optimally on the second day and then increase to 13 colonies/100 ml on day 5. The result of DO examination was an increase in DO on the second day to 8.2 mg/l which afterward finally decreased again the following day, this was due to an ozone reaction and bacterial activity in the water, therefore it was recommended that storage of drinking water after ozonation be stored for 2 days, and need renewal in the cleaning and disinfection of gallons to be used.

Fine bubbles (micro to nanometer-sized) have rapidly gained popularity in academia and industry due to their unique properties, such as their high surface area, stability, and longevity. In this study, the performance of oxygen transfer rate efficiency in fine bubbles with high purity oxygen and atmospheric air was analyzed. In this study, the developed fine bubbles generator with power requirement 300 watt was used to evaluate the production of fine bubbles and oxygen transfer efficiency at two type gas sources i.e., ambient air and high-purity oxygen in the small bench aqueous media (5 L water tank). The fine bubbles generator was set up at the pressure in 50 psi and gas flow rate at 0.3 L/min to produce fine bubbles in water medium. The effect of water recirculation process in the bubbles production was measured using particles size analyzer (PSA), zeta potential and dissolved oxygen (DO) meter to measure temperature and dissolved oxygen on the water. Dissolved Oxygen (DO) measurement shows the saturation value of oxygen concentration in water, for high purity oxygen is 30 mg/L higher than air which has a value of 8.64 mg/L. This causes the efficiency of gas transfer in high-purity oxygen to reach 72.09% higher than ambient air at 35.39%. The particle size distribution shows that the mean size of bubbles after 10 minutes recirculation was 465.5 nm and 599.9 nm correspondingly for ambient air and oxygen gas source. High purity oxygen also affect to the zeta potential value tends to be more negative than in ambient air. The type of high-purity oxygen gas can increase the efficiency of the oxygen transfer rate so that the gas containing high-purity oxygen increases the volumetric oxygen transfer rate coefficient which is 2 times higher than using ambient air.

Turbidity is an essential process variable in water treatment processes for clean water. This study reports the development of a mobile mini wastewater treatment plant (WTTP) intended to provide clean water in flooding incidents, where access to clean water is demanding. The mobile mini-WTTP employed with a fine bubbles generator aims to provide micro and nano bubbles with longer residence in the water expected to promote an effective flotation process. The system was evaluated in removing suspended solid capability to reduce total suspended solids (TSS) or water turbidity. The system consists of a mesh trap, chemical flocculation, dissolved air flotation chamber, and activated carbon–zeolite as a mineral filter. The system was tested on the suspended solid from homogenized clay resulted from a turbid tap water effluent with adjusted turbidity up to 500 FNU on the storage tank. Alum solution with a dosage of 200 mg/L was used as a coagulant agent. In the flotation process was introduced a fine bubbles generator with a pressurized mechanism. The effluent was pumped from a storage tank into a treatment plant with a flow rate of 200 L/h, and the samples were obtained after the separation from the corresponding sub-system at the condition of steady state of water flow. A digital water quality measurement was operated to evaluate the effluent after the separation process. The results show that the separation of turbidity up to 98% was obtained at the end of the processing system. The successful flotation of the suspended solid due to the zeta potential turn to zero up on the addition of flocculants lead to effective fine bubbles flotation. Finally, clean water was achieved in the performance test of mobile mini WTTP utilized with fine bubbles.