Wastewater treatment plants for great municipal units

The technology is unique since it incorporates all necessary and required operations and processes (nitrification compartment, pre-denitrification, final sedimentation compartment, aerobic sludge stabilisation, sludge thickening, if need be) in a single bioreactor. It results in low costs of acquisition, smaller bay, low operating costs.
The wastewater treatment installations for municipalities and built-up areas (type CC) are with the service range of 500 to 10 000 equivalent residents.

Features
High efficiency and low operating costs are two main characteristics.

1. High Activated Sludge Concentration
Traditional water treatment plants operate at low or medium concentrations of activated sludge. Our plants operate with higher concentrations of activated sludge that is one of precondition of high treatment efficiency.

2. All Processes May Be Integrated Into One Bioreactor
Most conventional technologies are split in many building parts – tanks, reservoirs, bioreactors, final sedimentation tanks, and the like. Our technology can carry out all these processes in one compact bioreactor, combining all necessary operations and processes and this fact has a favourable impact on operating cost and acquisition cost of wastewater treatment plants.

TECHNOLOGY - PROCESS DESCRIPTION:
Wastewater treatment plants of 300 E.O. capacities are supplied as readymade products – plastic or rust-resistant steel tanks with built-in technology, those of greater capacities are supplied as plant constructions with the technology to be installed.
On reconstructing wastewater treatment plants the existing tanks are reused and the plant auxiliary facilities are modernised, if need be. On treating industrial wastewater an aeration tank project is tailored to size and a degree of chemical pre-treatment is proposed and designed, if need be (wastewater of textile industry, dairy plants, etc...).

System Description
The bioreactor is a vessel partitioned into several interdependent spaces hydraulically interconnected. These spaces include mechanical debris collection, sand traps, denitrification, nitrification and final sedimentation. Wastewater is first screened to remove larger mechanical impurities by means of inlet screens for small plants and screens mechanically or manually cleaned, rotary drum screens and the like for bigger plants. Then mechanically pre-treated waste eater enters a denitrification compartment where it is mixed with activated sludge and the first treating processes start. Then wastewater under treatment with recycled activated sludge flows on to nitrification compartment – aeration. Other treatment processes continue to remove contaminating materials from wastewater. Clear water is separated from activated sludge in the final sedimentation compartment. Water flows off and sludge returns back to the system.

System Performance
Essentially, the bioreactor combines all function of conventional biological advanced treatment plants it operates with low sludge load, higher sludge age and reaches higher treatment performance. Reductions of BOD5 and Total Suspended Solids (TSS) under 30 mg/l are easily achievable. If observing the Operating Regulation of Wastewater Treatment Plants the below tabulated values can be obtained.

Effluent Discharge
The quality of the effluent allows its discharge into a receiving or storm sewerage. After disinfection the effluent can be reused for irrigation, washing of roads, pavements, etc.

Parameter		Average Performance
BOD5	(mg/l))	20 – 25
COD	(mg/l))	60 – 200
SS	(mg/l))	25 – 30
N-NH4	(mg/l))	2 – 5
Ptotal	(mg/l))	5 - 8

Excess Sludge
The activated sludge is a biomass consisting of microorganisms or of living matters using contamination of wastewater as their source of energy for life and reproduction. Entering contamination is converted to activated sludge. Thus the content of sludge continuously increases in the system. Sludge age of the technology supplied is longer than 26 days. This age provides fully for aerobic stabilisation.
ince the system is continuously supplied with contamination included in wastewater then after reaching the operational concentration of activated sludge – excess sludge has to be discharged from the system. A sludge facility is designed with respect to daily sludge production. Sometimes only a container is sufficient but even pre-thickening up to sludge dewatering to the concentration of ca. 20 weight percentage of sludge dry residue can be applied..