Abstract: An anaerobic fermentation apparatus has at least one fermentation tank. Each fermentation tank has a container, a pumping pipe, a conveying pipe, and a spray pipe. The pumping pipe communicates with the top of the container. The conveying pipe is mounted in the container. The spray pipe is mounted in the container and has a trunk and multiple branches. The trunk communicates with the conveying pipe. Each branch communicates with the trunk and has two nozzles formed through the wall of the branch. An imaginary connection line that connects the two nozzles is oblique with respect to the axis of the branch as viewed from the top, causing multiple vortexes at the bottom of the container to make the organic substances stirred thoroughly and the fermentation processing more evenly, and increase the efficiency of the fermentation.

Abstract: Provided is a system for purifying biogas. The system for purifying biogas utilizes a separating unit for methane and carbon dioxide that connects to a separating unit for biogas and a separating unit for carbon dioxide to separate methane and carbon dioxide from the biogas. The separating unit for methane and carbon dioxide may separate the methane and the carbon dioxide. The separating unit for carbon dioxide may separate water and the carbon dioxide. The system for purifying biogas provides high concentration methane for use as fuel for motor vehicles and recycle the water to separate biogas repeatedly.

Abstract: An anaerobic fermentation with venturi stirring equipment has a container, a circulation unit, and a spray pipe. The container has at least one opening. The circulation unit communicates with the container and has a pump, a pumping pipe, a conveying pipe, and at least one storage tank. The pump is disposed out of the container. The pumping pipe communicates with the pump and a top of the container. The conveying pipe communicates with the pump and is mounted through one of the at least one opening, and the conveying pipe is located in the container. A gas valve is mounted on the conveying pipe. The at least one storage tank is mounted on the conveying pipe. The spray pipe is mounted in the container and communicates with the conveying pipe. The anaerobic fermentation with venturi stirring equipment can promote the fermenting rate and the ecological distribution of the anaerobic bacteria.

Abstract: An electric separating apparatus has a separating tank and an electrical control. The separating tank has at least one first electrode panel, a second electrode panel, an upper separating region and a lower separating region. The electrode panels are vertically mounted in the separating tank to form the separating regions. The electrical control is electrically connected to the separating tank and has a transformer, a high-power resistor, a first A/C transformer, a second A/C transformer and a control unit. The transformer is electrically connected to an A/C source and the electrode panels. The high-power resistor is electrically connected to the transformer and the at least one first electrode panel in series. The A/C transformers are respectively connected to the high-power resistor and the electrode panels. The control unit is electrically connected to the A/C transformers to determine an electrical impedance of a liquid mixture in the tank.

Abstract: An electric separating apparatus has a separating tank and an electrical control. The separating tank has at least one first electrode panel, a second electrode panel, an upper separating region and a lower separating region. The electrode panels are vertically mounted in the separating tank to form the separating regions. The electrical control is electrically connected to the separating tank and has a transformer, a high-power resistor, a first A/C transformer, a second A/C transformer and a control unit. The transformer is electrically connected to an A/C source and the electrode panels. The high-power resistor is electrically connected to the transformer and the at least one first electrode panel in series. The A/C transformers are respectively connected to the high-power resistor and the electrode panels. The control unit is electrically connected to the A/C transformers to determine an electrical impedance of a liquid mixture in the tank.

Abstract: A method for producing fatty acid methyl ester has steps of providing waste oil with a fatty acid; proceeding a first, second and third esterification; and proceeding transesterification to obtain the fatty acid methyl ester. Because the method of the present invention uses low cost waste oil as a raw material, cost of fatty acid methyl ester can be decreased. Moreover, an amount of free fatty acid in the waste oil can be reduced by esterification, therefore, waste oil used in the transesterification has lowered amount of free fatty acid. Accordingly, the method has increased yield of fatty acid methyl ester.