Biodenitrification of treated wastewater at the M'zar Agadir wastewater treatment station

AbstractThe wastewater treatment technique adopted at the Grand Agadir M'zar is infiltration percolation on dune sand. This process produces clean water of good quality with the exception of nitrate overload, which is the major problem for the reuse of this water. Our work deals with the biodenitrification of treated wastewater. To do this, three experiments of the two types of mixed water (treated wastewater and treated wastewater in the primary stage) were carried out in a bioreactor with different proportions and a residence time of 24 hours. The proportions used were: 1/2 of treated wastewater and 1/2 of decanted water; 1/3 of treated wastewater and 2/3 of decanted water and in the last experiment we tested the recycling of 1/4 of treated wastewater and 3/4 of decanted water. The results showed that the recycling of 1/2 of treated wastewater allows us to reduce the nitrate load of the treated wastewater from 290 mg NO3/l to 125 mg NO3/l or a reduction of 57%. The recycling of 1/3 of treated wastewater allows us to reduce the nitrate load of the treated wastewater from 348 mg NO3/l to 71 mg NO3/l or a reduction of 79%. While, the recycling of 1/4 of treated wastewater result in a reduction in the nitrate concentration of treated water from 365 mg NO3/l to 12 mg NO3/l or a reduction of 97%.Keywords: Biodenitrification, Grand Agadir M'zar, Treated wastewater, Nitrate, Bioreactor