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RBBR Treatment System 1000 m3 /day

RBBR 

1Part 2

PART TWO

RBBR TREATMENT

SYSTEM DESCRIPTION

Table of Contents

2.1 General ........................................................................................................ 2

2.2 Process Description .................................................................................... 2

PART TWO

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ROTATING BED BIO REACTOR RBBR

SYSTEM DESCRIPTION

2.1  General

Sewage wastewater can be treated using different systems and processes, among these

 processes is the fixed film process also activated sludge process. Each of these pro-

cesses has distinct features. Historically the fixed film processes have provided sim-

 pler, more stable treatment systems with lower power costs.

On the other hand activated sludge treatment provides more flexibility and control of

the plant. And handle higher loads and meets higher effluent quality effluent standards.

The mutually exclusive advantages of the two processes have prompted engineers and

researchers to develop treatment systems which adequately combine the advantages of

each process while excluding their disadvantages.

2.2  Process Description

The technique of the combined process RBBR System for the biological treatment of

wastewater is a combination of the submerged fixed film process and the activated

sludge system, it is an advanced MBBR System.

Wastewater treatment according to the Advanced MBBR System is effected on the

one side by suspended activated sludge in the mixed liquor and on the other side by

fixed microorganisms in a biofilm on the surface of the contactors. This combines the

advantages of activated sludge and fixed film processes in one. The system works like

a conventional activated sludge system with activated biological sludge in the mixed

liquor with higher concentrations in the suspended sludge as usual and by the addition-

al effect on the biofilm in treatment.

The system integrates the two processes in a single tank entirely using a single me-

chanical drive system.

The immersed RBBR System Aerator is a wheel with a center shaft. The wheel is of a

cage design. The plates and discs in the contact aerators are formed with a special sur-

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face profile in order to assure maximum oxygen transfer and to form air chambers thatshall be self filled with during rotation. Hence only one mechanical drive is necessary.

An electric motor above water level rotates the contact aerator. By this atmospheric air

is dissolved in the mixed liquor to supply the activated sludge sufficiently with oxygen.

RBBR unit, with the biofilm formed on it’s surface

RBBR unit performing the aeration and mixing required foractivated sludge process

This RBBR complies with the requirements of an efficient aerator with lowest power con-

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sumption.

The mode of operation is the same as for the activated sludge process consisting of

the biotank (equipped with the Aerator) and the secondary final clarifier with a return

sludge circuit.

This system uses only a single mechanical drive for one wheel. An electrical motor

above water level rotates the wheel.

The oxygen supply for all microorganisms is ensured by rotating the wheel slowly.

As soon as a pipe emerges with its chambers above water level during this rotation,

the mixed liquor inside the chambers runs out which provides:

A- Excellent mixing

B- Additional aeration

The pipe then will be filled with atmospheric air that provides the Biological tank

with Air/Oxygen for the activated sludge process as well as provides the biofilm

with necessary oxygen that dissolves on the wet surfaces of the fixed biofilm.

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 Aeration openings in the RBBR discs which al low the aeration process and oxygensupply required for activated sludge process

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The sludge from a fixed film system have always a low sludge volume index, muchlower than in an activated sludge system with the same load. In this RBBR system

the waste sludge from the fixed film will influence the activated sludge in a way

that after short operating time the mixed liquor will change too.

The activated sludge of this RBBR-system is characterised by a low sludge volume

index. Therefore it's possible to operate the plant with always higher concentrations

of mixed liquor than in conventional activated sludge plants.

Small RBBR Unit

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Production line of RBBR units

2.3  Biological Reactor:

The treatment of the wastewater by the activated sludge process, with regards to

 process technology, operating and economic aspects, places the following require-

ments on the biological reactor (biotank):

- 

Sufficient enrichment of the biomass, measured simplifiedas the mixed liquor suspended solids concentration of the

activated sludge (MLSS) and the density of growth on the

fixed film surface area.

- 

Sufficient oxygen transfer to cover the oxygen uptake and

its control to match the different operating and loading

conditions.

- 

Sufficient mixing in order to prevent a permanent settling

of sludge on the tank bottom. As a rule, using this RBBR -system a sufficient mixing is given all the time even when

the speed of the wheel will be reduced in times of less oxy-

gen demand. An additional mixing device is not necessary.

-   No nuisances caused by odours, aerosols, noise and vibra-

tions. Simple slow-speed operation reduces operating noise

and vibrations. This RBBR-process operates with virtuallyno problem-causing odours; the oxygen supply is always

more than sufficient. The turbulence is only in the water

and inside of the wheel. No aerosols are released into the

air.

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Secondary Settling Tank (Final Clarifier)

Secondary settling tanks have the main task of separating the activated sludge from

the biologically treated wastewater.

The loading capacity of an activated sludge plant is determined substantially by the

concentration of suspended solids of the activated sludge and the volume of the

aeration tank. This RBBR-system is additionally influenced by the concentration of

the fixed film sludge.

In this project a secondary settling tank clarifier is a cross flow horizontal clarifier.

The sludge will return into the biotank by RAS pump. Waste sludge will be trans-

ferred to the sludge drying beds.

 

End of Part 2