Municipal,Industrial sludge (MS-IS) disposal faces significant environmental problems related to air emissions, threat to public health and contamination of soil and water resources, requiring therefore an appropriate treatment and careful management.
While world’s sludge production is on a relentless growth curve, environmental quality requirements for sludge are becoming increasingly stringent, disposal outlets are decreasing and economic pressures require low-cost solutions.
Disposing sewage sludge to landfills is considered a beneficial use only when such disposal includes methane recovery for energy production. However, use of sludge on land in the EU will not change dramatically in the future due to legislative restrictions. The proportion of recycled sludge to agriculture will remain almost constant despite to the growth in MS generation.
So that the incineration of the MS and recover the energy that generated in the incinerator become the most important and feasible solution in Sludge Management.
The ‘‘sludge-to-energy’’ approach is feasible with substantial benefits similar of those that any renewable energy source presents: decreasing the energy dependency of the WWTP and greenhouse gas emissions.
Fluidization is a method of mixing fuel and air in a specific proportion, for obtaining combustion. A fluidized bed may be defined as the bed of solid particles behaving as a fluid. It operates on the principal that when an evenly distributed air is passed upward through a finely divided bed of solid particles at low velocity, the particles remain undisturbed, but if the velocity of air flow is steadily increased, a stage is reached when the individual particles are suspended in the air stream. If the air velocity is further increased, the bed becomes highly turbulent and rapid mixing of particles occur which appear like formation of bubbles in a boiling liquid and the process of combustion as a result is known as fluidized bed combustion.
In fluidized bed combustion, rapid mixing ensures uniformity of temperature. The main advantage of fluidized bed combustion system is that municipal waste, sewage plant sludge, biomass, agricultural waste and other high moisture fuels can be used for heat generation.
A simple flow diagram of the structure is as above. Sludge will be stocked in the Bunker and pumped to the FBR. Sludge will burn in 2 stages and reaches to the boiler. Boiler generates pressurized saturated steam. Stack gas will be cleaned from ashes and solid particles in the filter. An inverter driven fan regulates the flow. Stack will be scrubbed and chemically treated and exhaust from the chimney. On the chimney emission control and monitoring will take place and records the emission parameters.