Is working in the field of fermenting agricultural, animal, and sewage waste to produce methane gas permissible, given that any fermentation process may be required to be avoided? And does what affects the worker from this waste during work necessitate repeating the ablution (wudu'), or is it sufficient to cleanse the hand and the affected area with water to perform the prayer?

There is no objection to converting agricultural and animal waste and sewage into methane gas for use as fuel. The resulting gas is pure, because transformation purifies. If some impurity from sewage or waste from animals not permissible to eat touches a person, it does not nullify ablution. It is necessary to wash the impure spot for prayer. As for the dung of animals permissible to eat, it is pure.