MUNICIPAL PLASTIC WASTE MANAGEMENT SYSTEM

INTRODUCTION

Use of plastics in the form of packaging materials, wrappers, carry-bags and other commodity items has become integral part of daily life. While plastics items waste having relatively low volume and reasonable weight and bottles are readily picked-up by rag pickers and kabariwala system, the low weight – high volume items become the part of municipal solid waste and get transported up to dumping yard. The thin, low density (High Volume-Low Weight) plastics become not only eye soar but also cause great nuisance to public at large. It flies all over and creates pollution. The quantum of solid waste is ever increasing due to increase in population, developmental activities, changes in life style, and socio-economic conditions, Plastics waste is a significant portion of the total municipal solid waste (MSW). It is estimated that approximately 10 thousand tons per day (TPD) of plastics waste is generated i.e. 9% of 1.20 lacs TPD of MSW in the country. The plastics waste constitutes two major category of plastics; (i) Thermoplastics and (ii) Thermoset plastics. Thermoplastics, constitutes 80% and thermoset constitutes approximately 20% of total post-consumer plastics waste generated in India. The Thermoplastics are recyclable plastics which include; Polyethylene Terephthalate (PET), Low Density Poly Ethylene (LDPE), Poly Vinyal Choloride (PVC), High Density Poly Ethylene (HDPE), Polypropylene(PP), Polystyrene (PS) etc. However, thermoset plastics contains alkyd, epoxy, ester, melamine formaldehyde, phenolic formaldehyde, silicon, urea formaldehyde, polyurethane, metalised and multilayer plastics etc. The environmental hazards due to mismanagement of plastics waste include the following aspects: ❯ Littered plastics spoils beauty of the city and choke drains and make important public places filthy; ❯ Garbage containing plastics, when burnt may cause air pollution by emitting polluting gases; ❯ Garbage mixed with plastics interferes in waste processing facilities and may also cause problems in landfill operations;

COMPOSITION OF MUNICIPAL SOLID WASTE

 

 PLASTIC WASTE RAISES THE FOLLOWING ENVIRONMENTAL ISSUES:

  • Indiscriminate dumping of plastic waste on land makes the land infertile due to its barrier properties.
  • Burning of plastics generates toxic emissions such as Carbon Monoxide, Chlorine, Hydrochloric Acid, Dioxin, Furans, Amines, Nitrides, Styrene, Benzene, 1, 3- butadiene, CCl4, and Acetaldehyde.
  • Lead and Cadmium pigments, commonly used in LDPE, HDPE and PP as additives are toxic and are known to leach out.
  • Non-recyclable plastic wastes such as multilayer, metalised pouches and other thermoset plastic poses disposal problems.
  • Sub-standard plastic carry bags, packaging films pose problem in collection and recycling. Littered plastics give unaesthetic look in the city, choke the drain and may cause flood during monsoon .
  • Garbage mixed with plastics interferes in waste processing facilities and also cause problems in landfill operations.

 

3 R PRINCIPLE OF WASTE MANAGEMENT :

 Reduce   Recycle  Reuse

 3-R Principle is well accepted and recommended principle of waste management.

The present technology is also based on 3-R principle. The volume of the waste is reduced by 85 to 90% which makes the waste recyclable for reuse.

 PROCESSING METHODOLOGY :

          Following steps are involved.

  1. The plastic waste is collected in bags or hopper from waste dumping yard.
  2. About 1 m3 (Weighing 40 to 50 kg) of plastic waste is put into the holding chamber of compaction / bale machine in two steps.
  3. The heating system is put on up to 5 minutes as required.
  4. The heating system is put off when plastics gets heated up to its softening point (50 to 600C)
  5. The hydraulic system is put on and compaction of heated plastics takes place.
  6. The volume gets reduced by 85 to 90% say from 1m3 to 0.15m3.
  7. The hydraulic cylinder is kept in place (compaction condition) and side doors opened.
  8. The wire is inserted to tie the compacted bundle mechanically too.
  9. The hydraulic cylinder is released and taken to initial position.
  10. The bale is taken out for storage. The plastics gets densified from 40 kg/m3 to 265 kg/m3

 

PLANT AND MACHINERY

 Hydraulically Operated Plunger type of Compaction Machine.

 Machine Size : 2 m x 2 m x 2.5 m

 

 

 CAPACITY OF MACHINE :


S.N.

Particular

Capacity

1.

Bulk density of loose plastics about

45kg/m3

2.

No. of trucks arrival with waste

40

3.

Capacity of each truck

200 cubic feet

4.

Total volumetric quantity of waste received

40 x 5.4

= 216 m3

5.

Total volumetric quantity of plastics waste received @20%volume

43.2m3

6.

Hold-up capacity of compaction machine

0.65m3

7.

Processing capacity of one cycle

1m3

8.

Cycle time of machine

10 mins.

9.

No. of cycles

6 per hrs.

10.

Volumetric quantity of waste compacted

6 m3 per hour

11.

Time required to handle total plastics with one machine

7 hrs.

 

RECOMMENDATIONS :

In the first phase 1 No. of machine be installed.

In the second phase 1 more machine should be installed.

 

ADVANTAGES

  1. The process is only for physical change of plastics from loose flying material to compact densified bale, hence environmental friendly.
  2. The nuisances of flying plastics is over come.
  3. Thermal and mechanical locking ensures compactness of bale during further transport.
  4. Further transportation cost is reduced to large extent.
  5. Value added dense plastic bale is produced from harmful nuisance causing municipal plastic waste.

 

LIMITATIONS

  1. Glass, Ceramics, metal pieces should be avoided to put in the system.
  2. Bio-medical / hazardous waste like insecticides should not be put in plastic waste reduction unit.
  3. Hydraulically operated system works at high pressure due safety precaution be taken.