METHOD AND SYSTEM FOR TREATMENT OF AGRICULTURAL AND INDUSTRIAL WASTEWATERS CONTAINING SOLIDS AND NUTRIENTS

摘要

A method and system of treatment of agricultural and industrial wastewaters that contain high concentrations of suspended solids, nitrogen, and phosphorus compounds is disclosed. The method and system includes pre-treating the wastewater, controlling the amount of coagulants used, and controlling the mean velocity used for mixing, surface loading rate, and solids loading rate. The method and system functions as a sedimentation unit and gas flotation unit (solid/liquid separator). The pH of the effluent wastewater is stabilized within the separator by ensuring that there is sufficient alkalinity to buffer the wastewater. Sufficient gas is produced in the coagulation reactions to float and concentrate the solids, which results in as high as 99 percent reduction in suspended solids, a 96 percent reduction of the phosphorus concentration, and a 50 percent reduction of the nitrogen concentration in the effluent from the separator.

主权项

1. A system of treatment of wastewater, the system comprising:
a chemical feed system configured to add acids, bases, or any combination thereof, to adjust a pH of a wastewater until at least 90 percent of alkalinity of the wastewater is in the form of a bicarbonate ion and the pH is between about 6.3 and 10.3, wherein the bicarbonate ion is a predominate carbonate species; a coagulant feed system configured to add a coagulant of ferric sulfate to the wastewater to produce carbon dioxide to buoy up coagulated solids; a separator having a lower settling zone configured to collect settled solids and an upper flotation zone to collect the coagulated solids of nitrogen compounds, phosphorous compounds, suspended solids, or any combination thereof buoyed up by the carbon dioxide by reacting the coagulant with the wastewater; and an effluent collection system in fluid communication with the separator.