Minimizing the recovery of phosphorus-containing pollutants in the process of wastewater sludge treatment

Summary

To improve the Baltic Sea basin the problem of reducing the concentration of nutrients, phosphorus in particular, in the effluents must be solved. No less important is to prevent bound phosphorus recovery in the subsequent process of activated sludge dewatering. It is shown that minimizing phosphorus recovery during sludge dewatering and preventing secondary pollution of effluents can be ensured by separate thickening of activated sludge and raw sludge; as well as by minimizing the retention time of activated sludge and raw sludge mixture before mechanical dewatering.

Kye words

biological treatment , dephosphatization , activated sludge , eutrophication , secondary pollution , sludge dewatering

Stabilization of corrosive water at the Petrodvoretz water treatment plant

Summary

In order to prevent corrosion in steel water distribution pipelines pilot tests of a water stabilization system fed with water from the South water treatment plant of Saint-Petersburg were carried out at the Petrodvoretz water treatment plant. During the entire period of chemical dosing steel passivation was achieved which provided for the tendency for iron concentration decrease at the test points of the Petrodvoretz water distribution network.

Key words

potable water , iron , calcium chloride , sodium carbonate , secondary pollution , corrosion activity , water stabilization system , network test point , passivation

A modern approach to the maintenance of gravity sewers of public utilities

Summary

Most public utilities are facing typical problems associated with severe wear of wastewater collection, transportation and treatment systems, as well as with hydrogen sulfide emissions, and deterioration of the treatment facilities operation. One of the main reasons is untimely cleaning of pipelines transporting wastewater resulting in the secondary pollution of wastewater. The solution to the afore-referenced problems lies in the proper organization of the integrated maintenance of gravity sewers. The most rational combined approach to the maintenance of gravity sewers is proposed, that combines reducing the capacity of the own structures of water supply and wastewater enterprises with inviting outsourcing companies for the scheduled maintenance.

Key words

secondary pollution , wastewater transportation , sewer network wear , hydrogen sulfide emissions , deterioration of the treatment facilities operation , outsourcing professional services , integrated maintenance of gravity sewers , combined method of workflow management