Turning Waste into Water – Abattoir Effluent
Today we were running some abattoir wastewater through the VSEP in our lab.
The feed water was effluent from the abattoir’s secondary waster water treatment ponds(anaerobic followed by aerobic) and had a TDS of 2,280 ppm. While a small volume of effluent is currently being resued for stockyard washdown some 250 kl/day of the effluent is being discharged to the sewer.
This abattoir is at the volume limit of what they can discharge under their trade waste permit. Applying to increase the limit is not that easy as the local sewerage treatment plant does not have the spare capacity to accept the additional volume.
Syngineering Water has proposed to use VSEP to separate the effluent into two streams, one of crystal clear clean permeate and the other a concentrated stream of all the contaminants. The cleaned water can be recycled and made available for use in production. This will not only reduce the volume of water being discharged but also decrease their consumption of municipally supplied potable water.
The operator of the sewerage treatment might be happy with the reduction in volume but they are not going to be happy to receive the concentrated stream. What to do with the concentrated waste steam is often a challenge. This is where things get really interesting. We are going to return this to the aerobic pond where we will introduce an algae and let mother nature work her magic on the nutrient rich water.
Using the VSEP with an RO membrane we can recover 88% of the abattoir wastewater as permeate. The bottles pictured above are samples of the before and after water and the volumes in each bottle represent the relative amounts of starting feed water, and final permeate and concentrate.
The permeate had a TDS of 105 ppm. The resulting concentrate had a TDS of 20,200 ppm.
The Business Case
In terms of costs, to treat one kilolitre of water the consumables (electricity, membrane wear, chemicals for cleaning and maintenance) comes in just under $1/kl. The cost of disposing of and then resupplying water is $7/kl. This represents savings of $350,000/year yielding a payback on the total project of less than 2 years.