Highland Cattle 23

Wastewater treatment and mixing

Dryden Aqua manufacture air diffusers for the treatment of farm slurry waste, the systems are applicable to any animal waste.  In the UK the majority are cattle, swine and chicken waste water.

Parameter  

(the waste water should be screened with a sludge pump or filtered down to 1000 micron) the data presented is for screened waste water

typical values           Performance
COD 4000 >95%
BOD 3500 >99%
Ammonium,  the ammonium will be removed by assimilation as well as nitrification, so nitrate concentrations will increase 1000 >99%
suspended solids  (if AFM is installed on the system then performance is improved to 99%) 1000 >90%

The animals produce a solid as well as a liquid waste.  The solid waste should be separated from the liquid waste by using a screened sludge pump.  The solid waster can then be composited and the liquid waste sent to treatment.

Air diffusers

The standard diffuser is one of our 3m long diffusers rated at 9 to 10 cubm/hr of air. The diffuser is fitted with a 1/2" hose tail, for connection on to 1/2" flexible hose. If a number of diffusers are required to treat a tank, a large diameter polyethylene pipe is fitted around the perimeter of the tank. The 1/2" hose is connected onto the air ring main, and the other end to a diffuser. The diffuser is then dropped into the tank.  If there is a lid on the tank, you can drill a 50mm diam hole and drop the diffuser through the hole.  The Dryden Aqua diffuser has its own internal ballast so it will stay on the bottom of the tank.  There is no need to empty the tank or secure anything to the base of the tank. Installation and maintenance is therefore quick and simple.

Aeration in the shed

The diffusers may be located in the cattle shed to aerate and mix the slurry below the floor of the shed. The air diffusers will keep the slurry aerobic and will eliminate many of the the noxious gases, this will improve the health and wellbeing of the animals as well as reduce respiratory disease and improve FCR (food conversion ratio).  1 x air diffsers and 10 m3/hr of air will mnix the slurry from 20 cattle or 100 swine.

Treatment of the waste water

Stage 1, dewatering

The first stage involves the removal of the solid matter.  The waste must be screened using a filter or a screened sludge pump to remove all solids above 1000microns.  The pump generates a solid waste and a liquid waster.

Stage 2, aeration activated sludge

The wastewater exits the shed and enters a series of tanks or open lagoons connected in series. The tanks / lagoons are operated as sequencing batch reactors (SBR), this helps to keep the good bacteria in the system, and clarifies the effluent at the same time.  If the system is not operated as an SBR but as a simple serial flow arrangement then a decantation tank is required as the last stage for sludge collection / disposal or bacterial solids recycling.

A typical system for 1000 cattle would comprises of 100 diffusers code 6.2.10 and two air blowers fitted with a 22 kw motor.  There will be two or more tanks connected in series, and the total volume in the tanks should give as long a residence time as possible, we recommend 40 + days for best results.  

For water treatment 1 x diffusers  and 10m3/hr of air is required for 10 cattle or 20 swine.

Stage 3. AFM tertiary treatment

The effluent from the SBR or decantation tanks should be below 100mg/l.  This effluent can be clarified with floculants and then filtered by AFM to reduce the solids content down to a suspended solids load of <5 mg/l.


Some additional information

animals Number of air diffusers required to treat the effluent
swine 5 diffusers and 50 m3/hr of air is required to treat the wastewater from 100 swine. The solids will have been removed, from the wastewater by screening down to 1000 micron prior to water treatment.
cattle 20 diffusers and an air flow of 200 m3/hr is required to treat the wastewater from 200 cattle. The solids will have been removed, from the wastewater by screening down to 1000 micron prior to water treatment .

Slurry (de-sludged)

The solid matter should be remove from the liquid component. The solid matter can be composted and the liquid matter treated.

A typical cattle farm raw waste will have the following characteristic

  • 56 litres of  waste liquid per day at 6% solids
  • 600 g/bod and approx 1.2 kg COD
  • 100 g of ammonium nitrogen30 g of phosphates
  • 30g of phosphates

Residence time of slurry in aeration tank 40 to 50 days, summer - winter

The system may require additional calcium and pH correction using Magphlow, to stop the system from becoming acidic. However, at the start up of a new system with high ammonium levels acid may need to be added to bring the pH down to 7.5. Once the bacteria established, the pH will start to fall, and this is when you need to add the Magphlow media.

Note.

The system will not only eliminate odour, and mix the waste, but with the addition of AFM you have class 1 irrigation water / fertilizer

 

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