Company ProfileCase Study: Dinmore Meatworks Abattoir—Dinmore, Australia
The Problem
The Dinmore Meatworks was looking for the safest and most economical method for emptying an anaerobic lagoon. The lagoon was 50m x 50m and was filled to a depth of 3.5m (8.75 million litres). A crust had formed to some depth, and heavy vegetation had grown over most of its surface. It had been taken out of service some 3 months previously.
A preliminary inspection by Hanson Sykes Pumps, Ltd., exploring the possibility of pumping the sludge from the lagoon, showed that the material was too thick to be economically pumped without some form of treatment to reduce the viscosity. Disturbance of the crust caused the sludge to release considerable odor, a major drawback to the plan to land spread the lagoon contents adjacent to the abattoir.The EversTech Solution
A preliminary test using bio-cultures and treating a small corner of the lagoon showed that this form of biological treatment rapidly modified the black, odorous, highly viscous sludge, to a brown, healthy biomass, easily pumpable and completely odor-free.
On the basis of the preliminary tests and other investigations, Dennis Evers of EversTech, along with the company's engineer, developed a strategy for a full-scale pilot project involving the following:
- Biological treatment of the whole lagoon by:
- injection of specially-formulated bio-cultures throughout the lagoon
- mixing by pumping and aeration
- Removal of the surface vegetation to a nearby pasture, once the sludge odor had been eliminated by the bio-culture treatment.
- Complete pump out of the sludge to adjacent fields, which had been rutted to assist drainage.
The overall project was completed within schedule (6 weeks), the land spreading was contained in the allocated area and conformed with the guidelines set down by the Water Quality Control Council of Queensland. A summary performance chart of the project is available.
After the initial short treatment and mixing period (five to seven days), all odor was eliminated from the pond for the duration of the program, also from the vegetation/sludge mixture spread on the pasture, and during land spreading and subsequent drying in the fields.
The treated sludge was positively flocculent, released water very quickly, stayed where it was spread, and dried in two to three days, after which it was possible to spread secondary layers of treated wet sludge. The treated sludge had significant fertilizer value, as indicated by an analysis of N:P:K at 5.0%:3.0%:2.0%, and by substantial grass growth stimulated on the areas where the sludge was spread.
Financial Benefit
Costs
The overall cost of Bio-Culture treatment, plant hire and labor for the project described was:
£3.00 per cubic meter
Costs of alternative strategies
If the lagoon had been treated with bio-cultures and then taken by tanker truck onto adjoining land and spread by slurry spreader, this would have cost:
£5.20 per cubic meter
If the sludge from the lagoon had just been trucked away and dumped at a certified disposal site, the dump fee plus transport and removal charges (at a distance of approximately 10 miles) would have been a total of: £45.00 per cubic meter
Conclusion
It was clear that the strategy adopted to empty the lagoon was the most economic and environmentally acceptable alternative. A complete Lagoon System Maintenance Program with bio-cultures was put into operation to reduce still further the costs and nuisance of waste disposal. The potential for a resource recovery system to eliminate the costs of waste disposal altogether has been investigated, and considering the value of the sludge spread on the land in this particular case study, the net benefit was in excess of £420,000.