Municipal solid waste (MSW) is a major problem the world-over due to the increase in the volume of household waste which is a direct result of the changes in lifestyle. Our environment and resources are challenged by doorstep collection and transportation to the landfill; the ever increasing methane and carbon emissions; rotting garbage; deteriorating air quality; the menace of birds, rodents, mosquitoes and flies; and the perennial problem of overflowing landfills and shortage of new locations. Fire hazard is another problem which adds to the deteriorating health of the local population.
Increasing opposition from residents, increased cost of land and landfilling, contamination of aquifers, and others are forcing industries and governments around the world to transition from centralised to decentralised methods of managing waste. However, the crux of the problem is the way waste is collected. Typically, the collected waste is unsegregated and, in many cases, even the segregated waste gets commingled during the course of its journey.
The dreaded “black bag”, the nightmare for all processors, contains commingled wastes containing organic matter, plastics, rubber, sanitary napkins, used adult and baby diapers, multi-layered plastics and numerous other things containing high levels of moisture. Conventional methods of treating MSW such as composting, would work only on organic matter over a period of time, but emits obnoxious odours. Post composting, the refuse derived fuel which includes plastic and rubber, remains a challenge.
The current method of reforming waste is simply inadequate. To address the issues of waste reformation, decentralised waste management at the source level would be the answer.
One such technology is at the heart of this and can be the most significant contributor in achieving zero landfill status for the country as it does not need segregation or drying of waste. Polycrack is the world’s first heterogeneous catalytic process that can reform wet, commingled MSW into usable energy like water, gas, carbon and light diesel oil on the same day as the waste generated. Thus, it leaves much less waste to be transported, stored or processed at a future time, or at a landfill.
The main advantages of Polycrack over conventional methods are:
- Pre-segregation of waste is not required to reform the MSW. Waste as collected can be directly fed into Polycrack
- Polycrack has high tolerance to moisture, hence no drying of waste is required
- Waste is processed and reformed within 24 hours
- As Polycrack is an enclosed unit, the working environment is dust free, resulting in excellent air quality
- Biological decomposition is not allowed as the waste is treated as soon as it is received
- Small footprint of the plant suggests that the area required for installing the plant is minimal when compared with conventional methods of processing.
- All constituents are converted into valuable energy thereby making it a zero discharge process
- Gas generated in the process is re-used to provide energy for the system thereby making it self-reliant and bringing down the operating cost
- There is no atmospheric emission during the process unlike in other conventional methods, except for combustion gases that have pollutants lower than the prescribed norms the world over
- Operates at approximately 450 degrees C, making it a low-temperature process
- Safe and efficient system with built-in safety features enables unskilled users to operate the machine with ease
- Low capital and operating costs
- Fully automated system requires minimum manpower
Environmental considerations of Polycrack
Polycrack is a closed loop system and does not emit any hazardous pollutants into the atmosphere. The combustible, non-condensed gases are re-used for providing energy to the entire system and thus the only emission comes from the combustion of gaseous fuels and is lower than the prescribed environmental norms.
The water recovered from MSW during the process is essentially steam condensed water and is clean and re-usable. The water is used for cooling water requirements and for horticulture purposes. There is no effluent water to be discharged from the plant.
The solid carbon residue is dry and powder-like and it can be compacted into briquettes and re-used as solid fuel in power plants. There are no solid residues disposed of from the plant. The process assists in achieving zero discharge and is environmentally friendly.
Plants working worldwide
A plant operating in the public sector processing industrial waste which was hitherto landfilled and gas from the unit is fed to their industrial kitchen.
A plant installed by a major aluminum manufacturer is using the plant to process kitchen and garden waste and the gas generated is used by their kitchen.
A plant installed at an international refinery location is converting automobile fluff and plastics to light diesel oil.
Several major plants are in the pipeline in New Zealand, Australia, Canada, Jordan, the Netherlands, and India for converting MSW, waste plastics, oil shale, etc. Similar plants are also envisaged for agro waste to provide organic carbon as a soil nutrient.
Various technologies at a glance: