It is illegal throughout the European Union to put human sewage into animal feed. The European Commission, which carried out the investigation into French animal carcass recycling plants has given France two weeks to make sure the practice stops. Farmers have not been directly accused of using sewage in feed. The inquiry affects plants which dispose of those parts of animal carcasses which are not used for human food. It would be hard to justify the use of human or any other form of sewage in feed.
Animal dung is very beneficial for farmland.
Spreading manure has long been a way of returning nutrients to the soil. But it is widely agreed that using it as an ingredient in animal food is running an unnecessary risk. It is also worth bearing in mind that even if animals ate untreated sewage and were contaminated by bugs like salmonella and e-coli, cooking the meat properly would kill them off and prevent the meat making us ill. Becoming vegetarian would obviously cut out all risk from BSE or other contaminated meat, but you could still face some risks from fruit and vegetables. Apples and carrots are just two crops where pesticide concentrations have been known to exceed recommended levels, and where official advice is to peel them before eating them.