412 results about "Volatile fatty acids" patented technology

A wastewater treatment process providing nitrogen, phosphorus, biochemical oxygen demand (BOD) and suspended solids removal comprises the steps of: passing wastewater containing ammonia nitrogen, phosphate, BOD and suspended solids, said wastewater mixed with recycled activated sludge from a subsequent step, into a first anoxic zone therein reducing nitrate nitrogen from the recycled sludge to molecular nitrogen; passing effluent from the first anoxic zone to a first aerobic zone therein oxidizing at least a portion of the BOD and oxidizing at least a portion of the ammonia nitrogen to nitrate nitrogen; recycling a portion of the contents at the end of the first aerobic zone back to the first anoxic zone; passing the effluent of the first aerobic zone to a second anoxic zone; introducing volatile fatty acid such as acetic acid into the second anoxic zone therein releasing phosphorus into a liquid phase; passing effluent from the second anoxic zone including the volatile fatty acid to a second aerobic zone therein substantially absorbing phosphorus into biomass and removing and/or oxidizing ammonia nitrogen; passing effluent from the second anoxic zone to a final settling zone therein separating: (i) a purified wastewater having decreased nitrogen, phosphorus, BOD and suspended solids and (ii) a sludge containing suspended solids, phosphate and BOD; and recycling at least a portion of the sludge (ii) to the first anoxic zone. In another embodiment, at least a portion of the sludge (ii) is also recycled to the second anoxic zone. In yet another embodiment, the second anoxic zone is divided into a first section and a second section. In the first section, anoxic conditions are established and in the second section, volatile fatty acid is added after anoxic conditions have been established.

The invention relates to a method for generating volatile fatty acid through anaerobic fermentation after the heat-caustic pretreatment is performed to organic waste with high solid concentration, and belongs to the field of the organic solid waste resource. The invention takes municipal sewage sludge as model substrate to conduct heat-caustic pretreatment, and then anaerobic acidification sludge after being treated in a heat stress and domesticated is taken as seed sludge to perform anaerobic fermentation. The solid quality concentration of the treated municipal sewage sludge can be 3.7 to 12.0 percent, the maximal productivity of the volatile fatty acid can reach 0.23g, and the organic matter in per gram of volatile fatty acid is increased by 20.1 to 61.0 percent compared with the fermentation acid with sludge which is not be pretreated. The method transfers organic matters in the solid waste, in particular, organic matter biology which is hard to degrade, to a product with economic value; the quantitative reduction of the organic solid waste is promoted; the problem that the environmental contamination caused by the solid waste is solved to some extent; the equipment for pre-treatment and fermentation process is simple; the operation is convenient; and the method has the advantages that the cost is low, the conversion rate is high, the fermentation period is short, and the production intensity is high.