SPECIFICATION OF A WASTE WATER TREATMENT UNIT FOR FAST FOOD RESTAURANTS
"High-Speed Bio Tec" Biological treatment plants. Advantages for restaurants; No need for grease trap, extremely compact and efficient compared to regular systems, clog free, handles shock loading, extremely compact, ready to be operated, fully automatic, skid mounted, and up front central control.
The Wastewater Treatment System is based on the Moving Bed biodegradation technology, which is unique due to its compactness and performance in respect of volumetric efficiency.
These technologies are combined with an airlift flotation system and a sludge re-aeration system in a modular tank that is prefabricated in the workshop and ready to be installed and hooked up to wastewater, power and outlet at the site.
Any treatment plant must be based on actual measurements of the waste stream with respect to hydraulic and organic load. The critical parameters are daily average flow, peak flow and influent/effluent COD, BOD5 and TSS.
Additional information on TDS, alkalinity, nitrogen and phosphorous are important for supply of chemicals and operation of the plant.
Wastewater from restaurants and other commercial food service facilities differs significantly from residential wastewater. In addition to higher surge volumes during busy periods and generally higher temperatures, restaurant wastewater is typically higher in strength than residential wastewater. This is due to higher levels of solids, oil and grease, which cause a higher chemical oxygen demand (COD).
Designs for new applications should be based on a full wastewater analysis and followed up by a test program in order to verify the design and guarantee the effluent. Such tests may range from biodegradability testing in lab scale to pilot testing on site.
The standard units specified below are based on the following parameters:
Any other effluent and sludge digestion requirements may be obtained
The treatment system comprise of the following major components.
Wastewater Collection Tank/Coarse Screen
It is assumed that restaurant and toilet wastewater piping ends in a customer provided wastewater collection tank with a coarse screen. The holding capacity should be approx 3 hours to level out extreme peak flow. An overflow exit to drain is to be provided.
A customer provided submerged feed pump should provide 2 m lifting head at the unit inlet flange, against closed valve.
ALF Primary Treatment System
An air lift flotation (ALF) treatment devise is integrated in the digester tank. It shall remove most of the oil and grease before wastewater enters into first MBBR.
In ALF system, air bubbles are formed by introducing air directly into the waste water through a disc shaped microbubble diffuser, with air supply from blower. This will lift the floating scum (oil and grease) out of the wastewater and overflow into the digester tank
The biological treatment system is consisting of two reactor tanks:
Biological Treatment System
A first Moving Bed Biofilm Reactor (MBBR) is acting as a roughing reactor to shave peak loads and remove most of the BOD.
A second Moving Bed Biofilm Reactor (MBBR) is acting as a polishing reactor to degrade the remaining BOD, down to the effluent BOD concentration required by the customer.
The MBBRs are filled with a specially designed biofilm carrier elements (BCE) which is free floating and moving around in the reactor with the flow. The medium provides an effective biofilm surface of 500 m2 per m3 bulk material. Simultaneously, biomass is trapped inside the carrier elements, providing additional surface for the bioculture.
The BCE filling rate may be varied from 33 % to 67 % to fit a specific BOD design load or accommodate for larger load variations.
Both reactor tanks are aerated through a coarse bubble air distribution system at the bottom of the tanks, with air supply from a side channel air blower.
Settling Tanks and Sludge Digesting System
The biodegraded water is flowing by gravity into the clarification stage where the suspended solids settle by gravity.
The settled sludge, thus being removed from the clarified water, is transferred into the integrated sludge digester tank with four days holding time, by the airlift provided by the ALF devise. The digested sludge are to be pumped into a customer provided container for dewatering and final disposal as food waste.