The sludge treatment system consists of two integrated modules.
1) Spiral Filter Press Dewatering Module
The spiral filter press dewatering module dewaters liquid sludge with percent total solids between 0.5% and 5% to sludge cake with percent total solids between 15% and 25%. Energy requirements for the spiral filter press is 1.0 KWH per dry ton of sludge.
2) Dehumidification Heat Pump with Mesh Belt
The second is a heat pump Dehumidification module that dries sludge cake with percent total solids between 15% and 25% to 90% totals solids or higher with low energy requirements.
The dehumidification heat pump utilizes the refrigeration principal to cool and dehumidify hot moist air. Through the heat pump principal, the heat pump recycles the latent heat released from steam congealing to water liquid. A Dehumidification heat pump is equal to: the Dehumidification or moisture removal process plus a heat pump or energy recycling process. A Dehumidification heat pump can internally collect all the latent heat and sensible heat during air exhaust, bringing no waste heat outside the closed system.
The evaporation of sludge moisture absorbs latent heat; and the condensation of the generated vapor on the heat pump cycle releases latent heat. The evaporation process absorbs the same quantity of latent heat that the condensation process produces, according to the laws of thermodynamics and the law of conservation of energy. As a result, the drying process does not require additional heat capacity, resulting in the reduction of energy requirement and hence operational cost. The energy consumed during the process is only the electricity needed to operate the compressors and the fans or air handlers. The Dryer adopts a mesh belt type closed cabinet, which eliminates odor and gas buildup.
The Mesh Belts have variable frequency control to vary their speed. The speed of the Mesh Belts can be reduced to arrive at a final drier biosolids or it can be increased to arrive at a final wetter biosolids output product.