Better Waste Management: Alternative Fuels & Raw Materials

Daily 0.2 million tonnes of waste is generated in India. Waste collection efficiency ranges between 20 and 25 per cent out of municipal waste collected. Of this 94 per cent is dumped in land and 5 per cent composited. Waste will increase between at phenomenal rate. between 2005 and 2025. This can be recycled to generate new products, such as cement and not just a waste incineration.Alexander Koshi is a chemical engineer with 39 years experience in cement industry in India, Saudi Arabia, UAE, Oman, Bahrain, Bangaladesh and Kuwait. He is a major international conference speaker.Cement manufacturing is a large scale industrial process with high energy consumption and a potential for co-processing of high quantities of alternate fuel and raw material (AFR). AFR can be recycled to generate new products, such as cement. It is not just a waste incineration. The co-processing of AFR in the clinker manufacturing process is environmentally-friendly.Evaluation Of AFRCharacteristics:

• Thermal substitution of coal with waste up to 40 per cent in 1 million tonne cement plant will reduce the CO2 emission by 100,000 tonne.
• Saves fossil fuel considering India’s kiln capacity of about 300 million tonnes 5 per cent substitution will save 2.5 million tonnes of coal annually.
• It is the most environment-friendly way to dispose hazardous waste as it recovers energy from waste and leaves no residue.
• Saves money. There is no need to invest in incinerators and landfills to dispose the hazardous waste that India generates. India’s present cement kiln capacity is good enough for the next decade or more.

Advantages of the clinker manufacturing using waste fuelsFirst of all, a utilisation of secondary or waste derived fuels, so called WDF?s in the clinker manufacturing process is a real recycling. It is not just an incineration. Moreover, due to the strict alkalinity of the process practically all inorganic compounds, like heavy metal elements are immobilised in the clinkers minerals without negative influence on the quality of the product as those compounds are diluted below as significant values. In addition these elements are not re-mobilised during the hydration process of the cement and hence no pollution, for example of the ground water is possible, as this is a serious problem of landfills.As proven by intensive investigations, the organical compounds of WDF’s are completely ed down to a methane-like base molecule by an extreme high temperature profile of the thermal system of up to 1550 ?C. This methane-like compound is easy to ignite and to combust.Furthermore, due to the high gas velocities and the related short retention time in the thermal system the window of de novo synthesis of dioxins and furans is very short and no significant reformation of those hazardous compounds takes place. In waste incineration plants, tremendous technical provisions are necessary in order to cover this problem.Liquid Waste Firing Through Burner

• Injection of the liquid waste should be done through the centre of the burner and coal as a primary fuel can be injected through the outer annulus. Higher velocity at the burner tip is required in case of multi fuel firing and hence necessity of an axial blower is envisaged in case the primary air quantum is low.
• Two phase injection nozzle for hazardous liquid waste firing is recommended to achieve sufficient fineness of the droplets
• Atomisation of the primary air is envisaged and hence any kind of compressor along with an air vessel is necessary to assure stable injection of the liquid waste. Air pressure of the compressor should be in the range of 6-8 bar for an atomisation viscosity of 25-40 cSt.
• Opening size of the nozzle diameter is of prime importance for firing of liquid waste due to its solid content (possibility of the nozzle to get plugged). Hence, required opening would be determined after having the detailed analysis of the solid content in the hazardous liquid waste.
• Precautions are to be taken to avoid any damage due to back pressure generating from the system during upset condition of the kiln, if any.

The Indian Waste Management ScenarioIndian population is 1.2 billion in roll and increasing. Daily 0.2 million tonnes of waste is generated around in 28 states and 7 union territories with total 38 million tonnes annually. Waste collection efficiency ranges from 20-25 per cent out of municipal waste collected 94 per cent is dumped in land and 5 per cent composited. Waste will increase between 2000 and 2025 at phenomenal rate. In 2009, about 67 million tonne of hazardous waste was generated.The waste collection will undergo the following changes.

• Organic waste will go up from 40 to 60 per cent.
• Plastic will rise from 4 to 6 per cent
• Metal will escalate from 1 to 4 per cent
• Glass will increase from 2 to 3 per cent
• Paper will climb from 5 to 15 per cent
• Others (ash, sand, grit) will decrease from 47 to 12 per cent

Action To Improve AFR

• India emerging as developed country must consider use of AFR in cement industry to improve quality of life of its growing population.
• The conditions in rotary kilns guarantee that the use of AFR is ecologically safe.
• The hazardous waste, more than 1,80,000 tpa is available. This can be used in cement kiln to produce 38 x 105 GJ of heat energy. This will help to reduce CO2 emission and solve land filling problem. Use of AFR in cement plants is both ecologically and economically justified.
• The barriers to AFR use in India are technological and economical barriers. But the critical issue who pays and globally it is found that the polluter pays. There is complete disconnect between the user and giver. The government has to setup laws and regulations followed by integrated solid waste management hierarchy (ISWM) with a strong legal frame work. Economical incentives have to be provided for RDF production and utilisation such as offering tax free and soft loan for machinery lower taxes for companies, those use RDF. The cement manufactures association with National Council of Building materials and central pollution control board (CPCB) with central and local governments must work in synergy to solve the problem.