This article originally appeared in the Small Systems Spring 2020 supplement as "Instant Infrastructure"
When a car dealership in Pennsylvania found the perfect piece of land for an expansion project, the price seemed too good to be true. Turned out, it was. Daniel M. Early, PE, senior engineer for OriginClear’s Modular Water Systems and its subsidiary, Dallas-based Progressive Water Treatment, was approached about finding a solution for this real estate development.
While the location and acreage were exactly what the dealership was looking for, they discovered that the property had no public sewage access, and worse yet, the land would not percolate, meaning that a conventional onsite sewage disposal system would not work either. The cost to connect to the nearest sewer line, several miles away, was prohibitive. Easement acquisition, engineering and construction costs, even with the relatively low cost of the land, made the off-site sewer line extension unviable.
This facility offered an opportunity to utilize emerging water treatment and reclamation technologies that could be easily implemented to deliver a sustainable wastewater reuse system. Would it be possible to design, build and deliver an advanced treatment system that would provide a closed-loop, “black box” system to treat the car dealership’s wastewater? The proposed concept would capture the waste, treat it to a high standard, disinfect it, store it, and recycle it back into the facility for toilet re-flush.
A Huge Change
The economic pressure on the dealership to expand the facility was intense, so the developer and consulting engineer were willing to consider the proposal.
A car dealership might have 20,000 to 30,000 square feet or more under one roof, but the actual wastewater demand would probably be less than 2,000 gallons a day—primarily from toilets and urinals, hand sinks and similar sources that generate domestic wastewater. The situation was ideal for using a closed-loop, zero-discharge, recycling-wastewater-reclamation system.
The team at OriginClear worked with the dealer’s consulting engineer and with the permitting and regulatory agencies in the state to implement the solution. This approach brought what was basically a commercially useless property and turned it into a valuable plot of real estate, once the dealership met the required regulations and got the needed permits to implement.
As a side benefit, the dealership also recognized the positive contribution to the environment, a low utility bill, and the advantages of utilizing green technology for reuse and sustainability.
The closed-loop recycling system compared favorably with the cost of a commercial-grade septic system while avoiding potential groundwater contamination and reducing potable water demands.
Those benefits increased when looked at holistially and as a bigger picture. This kind of water reclamation approach represents a difference in being an environmental steward. Commercial businesses are no longer relying solely on civil infrastructure to provide the needed resources.
Moving to a Point-of-Use Model
OriginClear’s closed-loop, zero-liquid-
discharge (ZLD), blackwater recycling system treats a facility’s raw sewage to a tertiary level, compliant with current wastewater reuse standards that allow the reclaimed wastewater to be recycled in toilets and urinals. The factory-prefabricated system was delivered fully assembled for rapid installation.
The specifications of the system included:
- A 96-inch inner diameter by 102-inch-deep multi-compartment high-density polyethylene (HDPE) membrane bioreactor (MBR) vessel;
- A 120-inch inner diameter by 40-feet-long multi-chambered effluent pump station and sludge digester (EPS-SD) vessel;
- An 8-foot by 8-foot factory-assembled modular wastewater treatment plant (WWTP) equipment building; and
- Treatment capacity nominally rated at 1,500 gallons per day (gpd).
How the System Works
The dealership wastewater first receives treatment in a primary clarifier chamber where solids and non-digestible matter are settled from the raw sewage. This employs a flow equalization (FEQ) chamber and provides temporary storage of the pretreated water and wastewater that comes in surges throughout the day.
The stored wastewater is systematically dosed to the downstream membrane bioreactor (MBR) system for final biological treatment where an analog level sensor provides real-time monitoring of FEQ water levels, and auxiliary mechanical float switches provide redundant operational control.
The MBR system provides advanced biological treatment of organics still contained in the pretreated wastewater and enhanced liquid-solids separation. A continuous aeration process scours and clears the membrane, which allows for sustainable effluent filtration. Analog level sensors provide real-time liquid level monitoring and system control.
Next, the filtered water is pulled through the system by suction pressure. A dedicated pumping system provides precise flow control, and sophisticated flow metering is used to monitor the process. The membrane system is equipped with a backwash clean-in-place (CIP) feature, providing systematic backwash of the membrane filtration unit. These pump systems are controlled by an intelligent programmable logic control (PLC).
Biosolids are pumped from the waste point to a dedicated sludge-holding chamber. The sludge is aerated while held to digest any organics and, after digestion, is periodically pumped and hauled away for final disposal.
The recycling water then receives final treatment in the form of a redundant disinfection system that uses ultraviolet (UV) light and tablet chlorination, ensuring the treated waters are rendered sterile. The fully treated wastewater meets the required specifications for compliance with wastewater reuse standards, as demonstrated in the table to the left.
The highly treated effluent is temporarily stored in a 10,000-gallon storage chamber equipped with an auxiliary aeration system that contributes dissolved oxygen to the reclaimed water, further improving final effluent water quality. The master control panel automatically operates the effluent recycling system, and pumping is monitored in such a way that reclaimed water can be continuously and effectively resupplied to the dealership for toilet and urinal re-flush purposes.
A programmable logic controller-based panel provides automatic operation of the wastewater treatment system. The panel is equipped with a web-based internet alarming capability that permits remote monitoring and operation functionality in real time.