Metals react with acid to produce hydrogen gas. Some of floor cleaner liquids contain concentrated strong acid such as HCl. This study was conducted to react metals (Zn, Al, Fe, Cu) with floor cleaner liquids (WPC and Vixal) that contain 17% HCl to produce hydrogen gas. The most hydrogen gases were resulted from reaction between Al and both of floor cleaner liquids. They show the same trend Al>Cu>Zn>Fe for the volume of hydrogen gas produced . It was not appropriate with theory due to different of surface area of each metals used.

Buffalo dung is buffalo digestive waste, which can cause problems for the environment and health. The buffalo dung waste contains macronutrients such as nitrogen, phosphorus, calcium, and water which have the potential as bioactivator for the composting process. The composting process using bioactivator from buffalo dung is an alternative utilization of buffalo dung solid waste. This study aims to show the potential of buffalo dung solid waste as a bioactivator in the composting process of organic waste and to obtain degradation data of composting organic waste using bioactivator from buffalo dung. The variables observed in this study were pH, TS, TSS, and Moisture Content. This research was started from making bioactivator from buffalo dung, then continued the composting process by putting organic waste into the tower composter while adding bioactivator until the water content reached 55-65%. Results the study found that the pH, TS, and TSS values in the manufacture of liquid fertilizer from buffalo dung were 4.28; 17.68 ppm and 6.9 ppm. Composting carried out for 20 days showed that the bioactivator of buffalo dung was able to influence the composting process, namely moisture content 50.23%.