Recycling - Energy recovery - Composting – Vermicomposting - Maturity indices assessment - Standards and legislation

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Recycling - Energy recovery - Composting – Vermicomposting - Maturity indices assessment - Standards and legislation

Recycling is the process of converting waste materials into new materials and objects. It is an alternative to "conventional" waste disposal that can save material and help lower greenhouse gas emissions. Recycling can prevent the waste of potentially useful materials and reduce the consumption of fresh raw materials, thereby reducing: energy usage, air pollution (from incineration), and water pollution (from landfilling).

Recycling is a key component of modern waste reduction and is the third component of the "Reduce, Reuse, and Recycle" waste hierarchy. Thus, recycling aims at environmental sustainability by substituting raw material inputs into and redirecting waste outputs out of the economic system.

There are some ISO standards related to recycling such as ISO 15270:2008 for plastics waste and ISO 14001:2015 for environmental management control of recycling practice.

Recyclable materials include many kinds of glass, paper, cardboard, metal, plastic, tires, textiles, batteries, and electronics. The composting or other reuse of biodegradable waste—such as food or garden waste—is also a form of recycling.  Materials to be recycled are either delivered to a household recycling center or picked up from curbside bins, then sorted, cleaned, and reprocessed into new materials destined for manufacturing new products.

In the strictest sense, recycling of a material would produce a fresh supply of the same material—for example, used office paper would be converted into new office paper or used polystyrene foam into new polystyrene. However, this is often difficult or too expensive (compared with producing the same product from raw materials or other sources), so "recycling" of many products or materials involves their reuse in producing different materials (for example, paperboard) instead. Another form of recycling is the salvage of certain materials from complex products, either due to their intrinsic value (such as lead from car batteries, or gold from printed circuit boards), or due to their hazardous nature (e.g., removal and reuse of mercury from thermometers and thermostats).

Energy recovery

Energy recovery from waste is the conversion of waste materials into usable heat, electricity, or fuel through a variety of processes, including combustion, gasification, pyrolyzation, anaerobic digestion, and landfill gas recovery. This process is often called waste-to-energy. Energy recovery from waste is part of the non-hazardous waste management hierarchy. Using energy recovery to convert non-recyclable waste materials into electricity and heat, generates a renewable energy source and can reduce carbon emissions by offsetting the need for energy from fossil sources as well as reduce methane generation from landfills. Globally, waste-to-energy accounts for 16% of waste management.

Composting

Organic matter constitutes 35%–40% of the municipal solid waste generated in India. This waste can be recycled by the method of composting, one of the oldest forms of disposal. It is the natural process of decomposition of organic waste that yields manure or compost, which is very rich in nutrients. Composting is a biological process in which micro-organisms, mainly fungi and bacteria, convert degradable organic waste into humus like substance. This finished product, which looks like soil, is high in carbon and nitrogen and is an excellent medium for growing plants. The process of composting ensures the waste that is produced in the kitchens is not carelessly thrown and left to rot. It recycles the nutrients and returns them to the soil as nutrients. Apart from being clean, cheap, and safe, composting can significantly reduce the amount of disposable garbage. The organic fertilizer can be used instead of chemical fertilizers and is better specially when used for vegetables. It increases the soil’s ability to hold water and makes the soil easier to cultivate. It helps the soil retain more of the plant nutrients.

To make a compost, select a cool, shaded corner of the garden. Shred the organic waste into pieces. Add cowdung slurry at the ratio of 3:1 and heaped. The entire heap is moulded using mud plaster or cow dung slurry leaving air holes to develop aerobic bacteria. The content is turned at regular (15 days). Preferably the bed should be lined with granite or brick to prevent nitrite pollution of the subsoil water, which is known to be highly toxic. At the end of 45 days, the rich pure organic matter is ready to be used.

Vermicomposting

Vermicompost is the product or process of organic material degradation using various species of worms, usually red wigglers, white worms, and earthworms, to create a heterogeneous mixture of decomposing vegetable or food waste (excluding meat, dairy, fats, or oils), bedding materials, and vermicast. Vermicast, also known as worm castings, worm humus or worm manure, is the end-product of the breakdown of organic matter by species of earthworm. Vermicomposting can also be applied for treatment of sewage sludge

Maturity indices assessment

          Compost maturity was chosen as one of the parameters for determining the grade of compost because it is so important to product performance. Immature compost may stunt, damage, or even kill plants, rather than enhancing their growth. Maturity is not related to quality, but to what stage in the composting process the material has progressed

Matured compost is very beneficial to plants, some of the intermediate stages of maturity may temporarily produce compounds, such as organic acids, that can be harmful to plant growth. Immature composts continue to break down once they are incorporated into the soil. This can affect plant health by consuming or tying up two resources that growing roots need. The high level of microbial activity in unfinished compost requires a large intake of oxygen, and the microbes may pull this from the surrounding soil, essentially suffocating the roots. The high carbon to nitrogen ratio (C:N ratio) of immature compost also means that, as the carbon compounds continue to break down, microorganisms will draw on soil nitrogen to assist in the process, leaving the root zone temporarily nitrogen poor. It is therefore crucial that responsible compost producers ensure that their compost has time to fully mature before selling it to most customers, as compost that is still “hot” when it is applied can do serious damage to both customers’ plantings and your reputation. A Note on Stability: The term stability is often used interchangeably with maturity. They are not really equivalent, however, and you must be sure you are assessing maturity, rather than simply stability, when monitoring your own process. Maturity: biological activity has slowed, as most remaining molecules are difficult to break down any further

          The use of more than one test is recommended, since presently no single test exists that can reliably verify maturity.  The compost must conform to one of the following four tests.

1. Carbon/nitrogen ratio (C:N) less than or equal to 25. As carbon is broken down through composting, the C:N ratio drops. Oxygen uptake less than 150 mg O₂/kg organic matter/hour. Microbes require oxygen, so a drop in the O₂ required signals a slowing of microbial activity. Germination of cress or radish seeds in compost equal to more than 90% that of control sample, and plant growth rate in soil/compost mix not less than 50% that of control sample. Cress (Lepidium sativum) and radish (Raphanus sativus) are small seeds, quick to germinate and sensitive to phytotoxic (plant damaging) substances like the organic acids temporarily present in immature composts.

2. Compost must be cured for a minimum of 21 days, and must not reheat upon standing to greater than 20⁰ C above ambient temperature. Microbial activity produces heat. When pile is no longer heating up, the level of microbial activity has dropped.

3. Compost must be cured* a minimum of 21 days and organic matter must be reduced by at least 60% by weight. As composting progresses, water vapour and carbon dioxide are given off, resulting in a lighter, denser product.

4. Compost must be cured for a six-month period. In the absence of other tests, six months under proper conditions to promote effective composting is considered sufficient to achieve maturity

Standards for compost

The maximum permissible limit prescribed by Govt. of India for metals in the finished compost viz., As,Cd,Cr,Cu,Pb,Hg,Ni and Zn were 10, 5, 50, 300, 100, 0.15, 50, 1000 mg kg^-1, respectively.  This value holds good for both organic compost and Phosphate rich organic manure. These standards are similar to Fertilizer control order (FCO 2000) for organic compost and FCO 2013 for Phosphate rich organic manure. The C/N ratio for both the compost should be less than 20. pH values for organic compost should be between 6.5 to 7.5 where as phosphate rich organic manure should not exceed the pH value of 6.7. The moisture content for organic compost should be between 15 to 25 % where as for phosphate rich organic manure it should not exceed 25%. The bulk density of organic compost and phosphate rich organic manure should be less than 1.0 and 1.6 g cm^-3, respectively. Minimum total organic carbon for both the organic compost and phosphate rich manure on weight basis  should be 12 and 7.9%,  respectively. Total N, P of the organic compost and phosphate rich organic manure should contain a minimum of 0.8 and 0.4% as N; 0.4 and 10.4 as P₂O₅ , respectively. The organic compost should contain minimum total K of 0.4% as K₂O_5. There is no minimum standard for K for phosphate rich manure. The colour of the organic compost should be dark brown to black and it should not have fowl odor. Minimum 90% material of both the compost should pass through 4.0 mm IS sieve. Salinity/ Specific conductivity of the organic compost and Phosphate rich compost should not exceed 4.0 and 8.2 d S m^-1, respectively. The details regarding specification of the compost for safe application is given in Annexure I

Legislation

The Environment (Protection) Act (1986)

This act confers power to the Central Government to regulate all forms of waste. Under this act several rules has been framed.   

1.   Municipal Solid Wastes (Management and Handling) Rules, 2000

The Municipal Solid Wastes (Management and Handling) Rules, 2000 shall apply to every municipal authority responsible for collection, segregation, storage, transportation, processing and disposal of municipal solid wastes.

2.   The hazardous wastes (management, Handling and trans boundary movement) rules, 2008

3.   Plastic waste (Management and handling) rules, 2011

Rule 10 states that no retailer can provide plastic bags free of cost.

4.   Biomedical waste (Management and handling) rules 1998

This include wastes from various institutions like nursing homes, animal houses, veterinary houses, blood bank, dispensaries, pathological laboratories etc., It prohibit mixing of biological waste with any other type of waste. The general rule provided is that the biological waste can’t be stored for beyond the period of 48 hours without being treated.

5.   E waste management rules, (2016)

These rules channelize the e-waste generated in the country towards authorized dismantlers and recyclers in order to formalize the e-waste recycling sector.  The manufacturer has to collect back certain percentage manufactures electronic items and send it to authorized recycler or dismantler.

6.    New Solid Waste Management Rules (SWM), 2016

The Union Ministry of Environment, Forests and Climate Change (MoEF & CC) recently notified the new Solid Waste Management Rules (SWM), 2016. These will replace the Municipal Solid Wastes (Management and Handling) Rules, 2000, which have been in place for the past 16 years. These rules are the sixth category of waste management rules brought out by the ministry.

Emission standards are completely amended and include parameters for dioxins, furans, reduced limits for particulate matters from 150 to 100 and now 50. Also, the compost standards have been amended to align with Fertilizer Control Order.

Annexure-I

In order to ensure safe application of compost, the following specifications for compost quality shall be met as per Govt. of India norms.

Parameters	Organic Compost (FCO 2009)	Phosphate Rich Organic Manure (FCO 2013)
Arsenic (mg/kg)	10.00	10.00
Cadmium (mg/kg)	5.00	5.00
Chromium (mg/kg)	50.00	50.00
Copper (mg/kg)	300.00	300.00
Lead (mg/kg)	100.00	100.00
Mercury (mg/kg)	0.15	0.15
Nickel (mg/kg)	50.00	50.00
Zinc (mg/kg)	1000.00	1000.00
C/N ratio	<20	Less than 20:1
pH	6.5-7.5	(1:5 solution) maximum 6.7
Moisture, percent by weight, maximum	15.0-25.0	25.0
Bulk density (g/cm3 )	<1.0	Less than 1.6
Total Organic Carbon, per cent by weight, minimum	12.0	7.9
Total Nitrogen (as N), per cent by weight, minimum	0.8	0.4
Total Phosphate (as P205) percent by weight, minimum	0.4	10.4
Total Potassium (as K20), percent by weight, minimum	0.4	-
Colour	Dark brown to black	-
Odour	Absence of foul Odor	-
Particle size	Minimum 90% material should pass through 4.0 mm IS sieve	Minimum 90% material should pass through 4.0 mm IS sieve
Conductivity (as dsm-1), not more than	4.0	8.2