公开(公告)号：FR2490623A1

公开(公告)日：1982-03-26

申请号：FR8020166

申请日：1980-09-19

Applicant: DEGREMONT

Inventor： PRINCE ANTOINE LE ,  NICOLAS FREDERIC ,  RICHARD YVES

IPC: A01K63/04 ,  C02F3/06 ,  C02F3/10 ,  C02F3/26

Abstract: Method for treating water in closed-circuit fish-farming systems comprises passing the water through a filter bed of solid material into which an oxygen-contg. gas is injected. This eliminates nitrogenous pollutants and replaces consumed oxygen in a single stage and, if necessary, also removes solid wastes. The flow rates of gas and water are controlled so that the pH is maintained at 5-9, esp. by stripping CO2 formed during the nitrification. Adequate purificn. is achieved in a single stage and treatment is carried out outside the fish-raising pond. Little or no fresh water needs to be supplied and stock levels 3-5 times higher than those generally used can be maintained. The filter material acts as a support for the denitrifying bacteria and the system can cope with large variations in the degree of nitrogen pollution.