Return activated sludge

Phenol can be oxidi2ed and hence removed, ie, to levels <20 / g/L, from wastewater (248). Moreover, addition of potassium permanganate to the return activated sludge results in reduction of odors issued from the aeration tanks of conventional activated sludge wastewater treatment plants without any change occurring to the microbiology of the system (249). 

ML Mixed Liquor - the combination of raw influent and returned activated sludge, (no, not mixed drinks for human consumption)... 

RAS Return activated sludge - settled activated sludge that is collected in the secondary clarifier and returned to the aeration basin to mix with incoming raw settled wastewater. 

RASVSS Return Activated Sludge Volatile Suspended Solids. 

The principal elements of the system include an aeration tank in which the wastewater is thoroughly mixed with continuously activated sludge and oxygen. From this part of the process, it passes into a clarifier tank, where the settled sludge is removed from the purified water to be recycled by the return activated sludge pumps. 

Fig. 1. Alternative wastewater treatment technologies, where GAC = granular activated carbon, PAC = powdered activated carbon, POTW = publicly owned treatment works, and RBC = rotating biological contactor (— ), wastewater return flows (—— ), sludge.

Comminution Shredding. A mechanical treatment process which cuts large pieces of waste into smaller pieces so that they won t plug pipes or damage equipment. Contact stabilization Contact stabilization is a modification of the conventional activated sludge process. In contact stabilization, two aeration tanks are used. One tank is for separate reaeration of the return sludge for at least four hours before it is permitted to flow into the other aeration tank to be mixed with the primary effluent requiring treatment. 

Return of the phosphate-stripped activated sludge to the aeration basin for reuse in a new cycle, where the phosphate-stripped activated sludge microorganisms are again induced to take up dissolved phosphorus in excess of the amount required for growth under aerobic conditions. 

Plant 000012 produces 3.9 x 10" kkg/year (8.7 x lO lb/year) of emulsion crumb rubber, primarily neoprene. The contact wastewater flow rate is approximately 8.45 m /day (2.25 X 10 gpd) and includes all air pollution control equipment, sanitary waste, maintenance and equipment cleanup, and direct contact wastewater. The treatment process consists of activated sludge, secondary clarification, sludge thickening, and aerobic sludge digestion. Noncontact wastewater, with a flow rate of approximately 1.31 x 10 m /day (3.46 x 10 gpd), is used on a once-through basis and is remrned directly to the river source. Contact wastewater is also returned to the surface stream after treatment. 

---