What is Drip Dispersal?
The drip dispersal system for dispersal of effluent wastewater is a unique fluid handling system for distributing effluent in soil. The system incorporates filtration, time and level controlled application, and ultra low rate drip distribution. The drip dispersal system will accommodate virtually any type of pretreatment process, whether septic tank (anaerobic), aerobic, lagoon, or any type of treatment facility.
Only primary treatment (the removal of large settleable solids) of sewage is necessary. Pretreatment for excessive BOD and oil and grease may also be necessary if sufficient land area or suitable soil is not available. For domestic strength and volume of sewage, the same area is needed as used in conventional pressure distribution systems.
Since the installation of the field distribution lines results in little soil disturbance, and effluent discharge volume from each emitter hole is insignificant, installation of the system has minimal site impact even in established lawns or park areas. There are no visible indications that the installation site is being used for disposal purposes. This system is especially suited for landscaped or wooded areas near buildings, trailer parks, apartment complexes or residential subdivisions.
The drip dispersal system is operated via a programmable logic controller (PLC) which is activated by standard float switches located in a dosing tank downstream from a pretreatment process (typically a septic tank). When activated by the rising level of effluent in the dosing tank, the controller will enable the disposal cycle and pump the effluent through a 115 micron disc filter and then to final drip dispersal.
The pump control panel is equipped with four float switches to control the timed doses to be discharged. The water level must be high enough to overcome the “Redundant Off” (Bottom) float in order for the pump to be permitted to run. When the water level rises high enough to overcome the “Dose Enable” (second) float and the time clock has timed out the preset time delay of “rest” minutes the pump will activate. The pump shall continue to run for the length of time as adjusted on the pump run timer and shall then shut off. The pump run time may be increased or decreased by a manual adjustment. The pump shall remain off until the internal time clock times out the preset time delay of “rest” minutes after which the pump will activate the next zone dose cycle (as long as the “Dose Enable” float is still up). This process is repeated until the water level drops below the “Dose Enable” float and the pump run timer has timed out.
The control system is equipped with a Peak Enable circuit to manage peak flows and excess water use. If the water level continues to rise enough to overcome the “Peak Enable” (third) float and the Peak Enable selector switch is on “pump” or “pump & alarm,” the lead zone will be dosed regardless of the time clock position and the rest period between doses will be reduced to increase the daily flow to each zone to 100% of the design flow, up from the standard 60%. When the Peak Enable circuit has been deactivated and the complete final zone dose has occurred, the standard pumping cycle will resume. If the water level continues to rise enough to overcome the “High Level” (fourth) float, the audiovisual alarm shall activate until silenced by pressing the Test-Normal-Silence switch to the silence position. The alarm circuit shall latch until manually reset after the “High Level” float returns to its normal position.
The (PLC) controller is enclosed in an outdoor electrical control box near to and connected to the hydraulic unit. This microprocessor has DC inputs and relay outputs for automatic operation of the drip disposal system. The manual switches (H-O-As) on the door of the control panel completely bypass the microprocessor. This will allow manual operation of the entire system in the event of a microprocessor failure.
The submersible pump delivers unfiltered effluent to each filter. The filter backflushing schedule is triggered at the beginning of each dose cycle. One filter valve closes, thus blocking the flow of unfiltered effluent to that filter. After a short delay, the other flushing valve opens, thereby backflushing the unused filter. The accumulated impurities discharge back into the pretreatment unit. The closing and opening procedure of the filter and back flush valves causes a change of flow within the unit to provide filtered water from one filter to backflush the other filter. The backflush procedure lasts approximately fifteen seconds then the back flushing valve closes. Only after the first filter has completed its backflushing cycle, will the second filter begin its cycle of backflushing in the same manner as the first.
After the backflushing cycle the effluent passes through each filter main valve, the filter, the flow meter and outlet manifold and is discharged below the soil surface through a patented chemical-resisting pressure compensating self cleaning “drip” poly-tubing emitter. The emitters or “drippers” are located every two feet in the tubing and emit 0.65 gallons per hour per emitter. The dripper lines are automatically scoured (forward flushed) every 50 dosing cycles. This function is activated by the controller which opens the field flush valve, thus allowing the flushed effluent to be returned to the pretreatment tank. The duration of this cycle is approximately three minutes. The flushing action creates a high velocity of the effluent which produces a cleaning action over the inside walls of the dripper tubing, PVC manifolds and emitters.
The construction of the drip tubing is unique in that the internal diaphragm and labyrinth provided for an exact amount of effluent to be discharged from each of its emitters which are normally spaced at two foot intervals along the entire length of the drip tubing. Each emitter maintains a constant flow over pressure ranges of 7 to 70 psi. Because the effluent is distributed at an ultra low rate, large quantities of effluent may be economically distributed over large areas during controlled periods of time without saturating the surrounding soil.