Water utilities are making various efforts to reduce water losses from water networks, and an essential part of them is to recognize the moment when a pipe burst occurs during operation quickly. Several physics-based methods and data-driven analysis are applied using real-time flow and pressure data measured through a SCADA system or smart meters, and methodologies based on machining learning are currently widely studied. Water utilities should apply various approaches together to increase pipe burst detection. The most intuitive and explainable water balance method and its procedure were presented in this study, and the applicability and detection performance were evaluated by applying this approach to water supply pipelines. Based on these results, water utilities can establish a mass balance-based pipe burst detection system, give a guideline for installing new flow meters, and set the detection parameters with expected performance. The performance of the water balance analysis method is affected by the water network operation conditions, the characteristics of the installed flow meter, and event data, so there is a limit to the general use of the results in all sites. Therefore, water utilities should accumulate experience by applying the water balance method in more fields.

The objective of this study was to determine the CH4 oxidation factor (%) and the CH4 oxidation rate (g m−2 d−1) in landfill cover soil. To quantify in-situ rates of CH4 oxidation, CH4 and CO2 fluxes were measured on a landfill site using the static chamber technique. The CH4 oxidation factor obtained in this study through the mass balance method ranged between 41% and 61%, which is much higher than the Intergovernmental Panel on Climate Change (IPCC) default value of 10%. The higher CH4 oxidation factor derived in this study can be explained by the CH4 bottom flux in addition to the soil texture. The CH4 oxidation factors were observed to increase with decreases in CH4 bottom flux. Therefore, when CH4 bottom fluxes are high in a landfill, using a gas collection system can enhance CH4 oxidation factor. The CH4 oxidation rates were estimated to range from 16.6 g m−2 d−1 to 20.8 g m−2 d−1. In addition, this study was conducted to evaluate the effects of vegetation on the CH4 oxidation factor. The results showed that the CH4 oxidation factors for bare soil, vegetated soil, and soil adjacent to a gas well were 57%, 70%, and 44%, respectively. The results indicate that vegetation on landfill covers can increase the CH4 oxidation factor because of increasing soil porosity.

Despite the wide distribution of air pollutants, the concentrations of indoor air pollutants may be the dominant risk factor in personal exposure due to the fact that most people spend an average of 80% of their time in enclosed buildings. Researches for improvement of indoor air quality have been developed such as installation of air cleaning device, ventilation system, titanium dioxide(TiO2) coating and so on. However, it is difficult to evaluate the magnitude of improvement of indoor air quality in field study because indoor air quality can be affected by source generation, outdoor air level, ventilation, decay by reaction, temperature, humidity, mixing condition and so on. In this study, evaluation of reduction of formaldehyde and nitrogen dioxide emission rate in indoor environments by TiO2 coating material was carried out using mass balance model in indoor environment. we proposed the evaluation method of magnitude of improvement in indoor air quality, considering outdoor level and ventilation. Since simple indoor concentration measurements could not properly evaluate the indoor air quality, outdoor level and ventilation should be considered when evaluate the indoor air quality.