The Freeze Dry Unit allow users to save money regarding energy, operation and transportation costs. In addition, the Freeze Dry Unit gives a valuable resource as a final product.
One of the drawbacks using today’s methods for sludge dewatering and drying is a high demand of energy. Sludge treatment can make up about ten percent of the treatment plants total energy use, which is significant.
The Freeze Dry Units energy cost is far below that of traditional sludge treatment methods on the market today. In comparison with a screw press for dewatering and a belt dryer for the final drying, the Freeze Dry Unit only uses a tenth of that energy, considering the mass of water removed.
As the Freeze Dry Unit can dry sludge to a dry substance of above 95 percent, the mass and volume of the sludge is drastically decreased compared to a lot of today’s methods. This results in up to 80 percent fewer transports which greatly affects transportation costs.
The Freeze Dry Unit is a robust and future proof solution designed for minimum and simple maintenance, dependability and long lifespan. The economic lifespan for the Freeze Dry Unit is 15 years.
A Swedish treatment plant for sewage waste produces about 20,000 cubic meters of sludge, with two percent dry substance and uses 12 cubic meters of polymers each year. Transportation of polymers are from France and the cost of polymers are € 24 221 a year. The sludge treatment is operational 5,200 hours a year. The treatment plant uses a screw press to dewater the sludge. The distance between the treatment plant and location for disposal is 80 kilometres. All dewatering and drying methods have an economic lifespan of 15 years and the discount rate is four percent. The price of energy is € 0,07 per kWh.
A screw press has an annual energy cost of € 678 and dewaters the sludge to a dry substance of 25 percent. Transportation costs are € 130 424 a year when the sludge is transported between the treatment plant and disposal location. In this case, maintenance is calculated to be € 9 316. Investment costs or costs for installment are not considered because the treatment plant uses a screw press today and therefore, does not have to make an investment or install anything. The total lifecycle cost is € 1 830 532. This is equal to € 4,38 per kg DS.
If the treatment plant would like to dry the sludge further, up to 95 percent dry substance, they could use a belt dryer after the screw press. The combination of a screw press and belt dryer has an annual energy cost of € 96 613. The investment of a belt dryer is € 1 257 662. In this case, due to decreased sludge volume, the transportation costs are only € 26 084. The installation cost is € 5 589 and maintenance costs are € 27 946 annually. The total lifecycle cost is € 3 301 343. This is equal to € 7,92 per kg DS.
If the treatment plant would use the Freeze Dry Unit to dewater and dry sludge to a dry substance of 95 percent, the energy cost would be € 67 820 a year. There is no need for a screw press and no polymers must be added to achieve dewatering and drying. This eliminates all costs associated with polymers. The transportation costs are only € 26 084, due to a decrease in volume a dryer sludge product results in. The installation cost is estimated to be € 931* and the maintenance costs are estimated to be € 9 316* annually. The total lifecycle cost for the Freeze Dry Unit is € 2 275 936, which equals € 5,5 per kg DS.
*These costs could change