Integrated Water- and Wastewater Project - Bulgaria

Establishment of a mechanic and biological sewage treatment plant

A mechanic and biological sewage treatment plant is planned to be built with advanced wastewater purification and sludge stabili-sation in the city of Cherven Brjag. The plant is initially considered for 15,000 PE and will be extended to 22,500 PE from 2020 onwards. Therefore, working out a concept for the first stage already includes the extension design for the future.
The activated sludge process with primary denitrification and aerobe sludge stabilisation was chosen. In addition, biological phos-phor elimination was taken into consideration. The sewage treatment plant basically consists of an inlet lifting system with a coarse screen, a combined fine screen and grit chamber unit, two aeration tanks, a clarifier, a sludge drainage system with a sludge silo and a sludge liquor storage tank, chlorination and an operation building. Design of the distribution network and prepa-ration of applications for the European Union support were carried out by Bulgarian partners.

Project/technical data:

Capacity	15,000 PE
Qth	184 m³/h
QM	367 m³/h
COD	< 125 mg/l
BOD5	< 25 mg/l
TSS	< 35 mg/l
Ntot	< 15 mg/l
Ptot	< 21 mg/l
pH	6 - 9