Grey Water Recycling System
Grey water is moderately loaded with biological contamination and dirt from household bath washing water drainage.

Process Description:

The process of gray water treatment is based on the following principal:
• Flow Equalization.
• Coagulation & dosing.
• Aeration for aerobic digestion.
• Sand Filtration.
• Activated Carbon Filter.
• Post Chlorination.

Flow Equalization:
The Grey water from within the complex is collected and equalized in the gray water collection tank. This done to dampen the variation in hydraulic & organic load .The contents of the sump is kept in agitated condition to avoid purification and settling of suspended solids. Agitation is achieved with help of air, which is injected through coarse bubble diffuser/ perforated pipe in the tank.

Coagulation & Flocculation, Precipitation And Sedimentation (optional)

Coagulant like Ferric chloride is added for coagulation of the suspended particles and easy settling. Addition of Polyelectrolyte/ flocculants is done for the flocculation of the suspended particles.

Aeration:

Air is forced to the water tank through a diffuser network at the bottom of the tank to increase the rate of dissolved oxygen for aerobic microbiological “digestion” of organic substances available in the water and to prevent anaerobic culture, which may lead to produce bad smell of the water system.

Sand Filtration:

Most of the organic load is associated with the suspended solids and to a very small extent in dissolved form. In order to remove the suspended solids the grey wastewater is pumped under pressure to the automatic pressure sand filter. As solids accumulate in the sand bed the pressure loss through the media rises & periodically reaches a value above which the plant will not further as designed. At this time the filter needs to be backwashed clear of accumulated solids. The media is backwashed by controlled flow of treated effluent delivered from the treated effluent delivered tank by using the back wash pumps.

Activated Carbon Filter:

The presence of dissolved BOD necessitates the use of an activated carbon filter. The filtered gray water passes through a bed of activated aarbon. The porous media having large surface area helps to absorb remaining organic matter on to the surface. The media is backwashed by controlled flow of treated effluent delivered from the treated effluent delivered tank by using the back wash pumps.

TIP: One gram of activated carbon granules have great surface area due to surface cracks of almost 50 to 150 m2

Post Chlorination:

The filtered water is then dosed with Sodium Hypochlorite for further removal of
organics, disinfections and to maintain enough residual free chlorine. Controlled and metered by automatic dosing and monitoring digital device.

Plant Operation:

The plant runs on automatic mode with possible re-setting by end-user to meet a the actual operational conditions.

Reference Projects:

….. and many others