The need to safely dispose of manure from concentrated animal feeding operations is resulting in some imaginative approaches. One North Carolina hog producer thinks one approach might be to attach a commercial greenhouse operation to the hog business, where a portion of the liquid manure is used to generate another cash crop – in this case, tomatoes. Why tomatoes? Barham chose tomatoes because he felt they would absorb a higher volume of treated wastewater than other vegetable crops. The farm installed a Caterpillar 3406 engine with a 120-kilowatt generator to
burn the biogas coming off the digester to generate electricity. The engine is capable of handling gas containing significant amounts of hydrogen sulfide, so nothing is done to clean the biogas before it is burned. For odor control, wastewater diverted to the farm’s greenhouses and hog barn manure pits undergoes a biological nitrification process.