Wastewater Reclamation and Reuse System

Developed over the course of the last three decades, Sheaffer & Roland’s Wastewater Reclamation and Reuse System (WWRRS) provides an environmentally sensitive and odor-free approach to wastewater management. In this system, the wastewater is first reclaimed in deep aerated cells, followed by filtration and disinfection. The product is reclaimed water which is reused to irrigate and fertilize agricultural crops, landscape vegetation or recreational turf. It is applied at a rate consistent with plant needs, climatic environment, and soil conditions. When wastewater is reclaimed and reused there is no effluent disposal or discharge site. Rather, there is a utilization site where reclaimed, pathogen-free water containing basic plant nutrients like nitrogen, phosphorous and potassium are used to irrigate and fertilize growing plants. The water is cleansed further by the living filter of plants, soil, and geology to help to recharge local groundwater supplies.

Elements of the Deep Cell WWRRS

The following elements typically comprise the treatment and reuse train for a deep-cell WWRRS in an urban setting as designed by Sheaffer & Roland, Inc. (S&R).

• The comminutor grinds up sewage solids before the wastewater enters the aerated cells. The comminutor is covered to prevent odors.

• There usually are two deep aerated treatment cells with a total retention time of two to five weeks. Wastewater enters at the bottom of the aerated cells to prevent odors. The cells are designed to allow for the settling of solids, which collect in the containment area where final decomposition occurs. The small volume of residual solids may be removed once every 20-40 years.

• Storage reservoirs provide reclaimed water during cold weather, precipitation, or other non-irrigation periods.

• Filtration increases the efficiency of the disinfection process (see below) and minimizes clogging of irrigation equipment. It is not needed for agricultural irrigation. Intermittent slow rate sand filters or gravity sand filters normally are used.

• Disinfection is commonly used in situations where there is a high degree of human activity in the irrigation area such as with golf courses, public parks, sports fields or other recreation or picnic areas. Disinfection is typically accomplished by chlorination.

• The Operations Building is a small structure that houses the air blowers, all electrical controls, telemetry equipment, and disinfection equipment.

Public Health Aspects of the S&R WWRRS

Within the S&R design, aggressive aeration - along with filtration, disinfection, and redundancy - provide the highest level of protection against potential public health problems. The resulting high level of purity presents no threat to human contact. The following treatment processes are part of S&R’s system:

• More than a month's total detention in the aerated treatment cells.

• Up to 150 days of retention in the storage reservoir also provides for significant pathogen reduction.

• Sand further assures removal of suspended solids and to break up biological "clumps" prior to disinfection.

• Chlorination assures a pathogen-free irrigation water supply.

Odors in Wastewater Treatment Processes

Under certain conditions, offensive odors are produced when organic compounds decompose and are exposed to the atmosphere. Odors are prevented in the S&R exclusive deep-cell system under nearly all conditions.

• Untreated sewage is not exposed to the surface; it is introduced near the bottom of the cell, where it is covered by from 15 to 25 feet of heavily aerated water. During the ongoing treatment process the organics are decomposed by oxidation.

• The residual solids are deposited on the bottom in a storage area where the remaining organics decompose in the absence of oxygen (anaerobically) for years. The S&R system is designed so that even under highly variable wastewater flows and characteristics there will be no difference in treatment effectiveness.

• Reserve aeration capacity is just one of the keys to this quality. S&R systems solve the sludge odor issue by not producing sludge in the first place. Thus, unlike conventional sewage treatment plants that produce sludge which must be removed as part of their regular operation, there simply are no odors associated with sludge removal.