Industrial Waste Water Treatment – Phase 2

The industrial waste water treatment is separated into 3 main phases, each phase being more or less advanced and complex depending on the nature of the effluent to be treated and the discharge standard in force.

Phase 2 is the biological process which has the objective to remove of Carbone, Nitrogen and Phosphate. The biological treatment is usually separated in 3 different phases:

1. Aerobic Phase:

Activated sludge aeration stage during which air diffusers blow air into the water basins to accelerate the bacteria removal efficiency. The bacteria are consuming the organic content in the waste water, part the sludge are being recirculated at the beginning of the aerobic phase.

2. Anaerobic Phase:

Denitrification is operated under anaerobic conditions which means that some phase of the biological treatment will be operated without air blowers.

3. Settling and Sludge Removal:

Biosolids accumulated in a wastewater treatment process are aggregated and removed in the settling tanks where they cumulate and drop by gravity and with the help of flocculants if necessary.  These may be contaminated with toxic organic and/or inorganic compounds such like heavy metals.

 

Biological Treatment Specific Technologies

Depending on the nature of the effluent, the space available and the discharge parameters some compacts technologies may be used.

Membranes Bio Reactors (MBR) technology is recognised worldwide for reliably producing high quality effluent, offering distinct advantages over Conventional Activated Sludge (CAS). MBR performance is more robust than CAS, producing final effluent lower in solids and chemical oxygen demand  and using only 10% of the space .

Membrane Bio Reactor, source: Chemarea

UASB (Upflow Anaerobic Sludge Blanket) has been developed in The Netherlands in the 70’s to perform high rate anaerobic treatment. A special collection point is integrated in the reactor to collect the biogas which can be reused to produce energy.

Sources: Water Treatment Books , Chemarea and Environmental Thinking