When wastewater enters the treatment plant, it first goes through a screening process and a grit removal process that removes debris/trash and grit (sand, gravel, etc.) from the wastewater that can interfere with the proper operation of the plant.  This material is then disposed at a landfill. 

Following the screening and grit removal processes, the wastewater is pumped through three settling tanks for primary treatment.  These tanks serve to remove the heavy organic solids and floatable solids (scum) from this flow.  The organic solids are pumped to the gravity thickener tanks for thickening, and the floatable solids are collected and disposed at a landfill. 

Following primary treatment the wastewater is pumped into two aeration tanks, which then flows by gravity into four secondary clarifiers for secondary treatment.  The RVSA’s secondary treatment system is a biological activated sludge process that utilizes fine bubble diffusers and is operated in a step-feed configuration followed by clarification.  This process serves to remove organic material from the flow.  The biological solids wasted from this process are pumped to the gravity thickener tanks for thickening, and the clarified treated wastewater then flows by gravity to be disinfected. 

Disinfection is accomplished by the addition of a 15% sodium hypochlorite solution to the clarified discharge from secondary treatment, and the disinfected effluent is released into the Arthur Kill. 

The sludges removed from primary treatment and from secondary treatment are first pumped to the three gravity thickener tanks and then to the two gravity belt thickeners.  These processes serve to concentrate the combined sludges through the removal of water. 

Following the thickening processes, the sludge is pumped to the three anaerobic digestion tanks.  The anaerobic digestion process serves to biologically stabilize the sludge in the absence of air.  It also dramatically reduces the total sludge mass, and inactivates pathogenic (disease causing) micro-organisms.  As a byproduct of the process, methane gas is produced, which is used by the RVSA to heat the plant and to drive the aeration system blowers. 

Following anaerobic digestion, the sludge is pumped to the sludge storage tanks and then to the dewatering facility.  At the dewatering facility, the sludge is mixed with a polymer and then pumped to one or more mechanical dewatering devices (belt filter presses and/or centrifuges) for the further removal of water from the sludge.  The RVSA is able to achieve a dewatered sludge of approximately 25% total solids through the use of these mechanical dewatering devices. 

The dewatered sludge is then discharged into trailers, for transport to sites where it is beneficially reused (i.e., in agricultural applications, for the reclamation of strip mining sites, or as landfill cover material)

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