Effect of nitrogen and phosphate on the activated sludge efficiency in domestic wastewater purification

Abstract

The activated sludge plants are the most newly effective treatment for domestic wastewater. These living systems required many factors to decompose and remove the colloidial and dissolved organic substances. Heather conditions including temperature,sun shine and duration, also pH and sensitization time, in addition to the nutrients as nitrogen and phosphate are some effective factors on its efficiency.

This study is performed on Saddam dam project at the activated sludge treatment plant. The plant recieves (1000–1500 m³/day) as a domestic wastewater. The physical characteristics of the sludge were less than the desirable values, as the bacteria is a prevaling microorganism with uncommon amount of algae, fungi and protozoa. The values of T.K.N.NO₃‐¹,T.P, PO₄∗^‐3 and BOD through the treatment units showing a bad removal efficiency. The ratio of BOD/N/P is (100/0.56/1.32) which have a bad effect on the workability of sludge. The BOD curve showing the occurrence of nitrification of about fifty percent of the total BOD. On the other hand the denitrification have been happened. These two phases decreased the nitroge compounds. The (K) value was greater than the typical, where the present value reaches (0.232/day). This can be regerded as a good results for fast degradation but it needs a lot of oxygen.

Many modifications could be done on the present plant to improve its efficiency. Complet mixing of wastewater with excess amount of return sludge, in addition to the carefully aerators working to prevent unaerobic decomposition. Also the high concen‐teration of effluent nutrient must be decreased to protect the water course from the polluted source.