Trends in Food Waste Management

Food waste is an untapped energy source that mostly ends up rotting in landfills, thereby releasing greenhouse gases into the atmosphere. Food waste is difficult to treat or recycle since it contains high levels of sodium salt and moisture, and is mixed with other waste during collection. Major generators of food wastes include hotels, restaurants, supermarkets, residential blocks, cafeterias, airline caterers, food processing industries, etc.

In United States, food waste is the third largest waste stream after paper and yard waste. Around 12.7 percent of the total municipal solid waste (MSW) generated in the year 2008 was food scraps that amounted to about 32 million tons. According to EPA, about 31 million tons of food waste was thrown away into landfills or incinerators in 2008. As far as United Kingdom is concerned, households throw away 8.3 million tons of food each year. These statistics are an indication of tremendous amount of food waste generated all over the world.

The proportion of food waste in municipal waste stream is gradually increasing and hence a proper food waste management strategy needs to be devised to ensure its eco-friendly and sustainable disposal. Food waste can be recycled via:

  • In-vessel composting (IVC): A treatment that breaks down biodegradable waste by naturally occurring micro-organisms with oxygen, in an enclosed vessel or tunnel;
  • Anaerobic digestion (AD): A treatment that breaks down biodegradable waste in the absence of oxygen, producing a renewable energy (biogas) that can be used to generate electricity and heat.

Currently, only about 3 percent of food waste is recycled throughout U.S., mainly through composting. Composting provides an alternative to landfill disposal of food waste, however it requires large areas of land, produces volatile organic compounds and consumes energy. Consequently, there is an urgent need to explore better recycling alternatives. Anaerobic digestion has been successfully used in several European and Asian countries to stabilize food wastes, and to provide beneficial end-products. Sweden, Austria, Denmark, Germany and England have led the way in developing new advanced biogas technologies and setting up new projects for conversion of food waste into energy.

Of the different types of organic wastes available, food waste holds the highest potential in terms of economic exploitation as it contains high amount of carbon and can be efficiently converted into biogas and organic fertilizer. Food waste can either be used as a single substrate in a biogas plant, or can be co-digested with organic wastes like cow manure, poultry litter, sewage, crop residues, abattoir wastes, etc.

Enhanced by Zemanta
Advertisements

Vermicomposting

English: Freshly harvested worm castings Categ...

Vermicomposting is a type of composting in which certain species of earthworms are used to enhance the process of organic waste conversion and produce a better end-product. Vermicomposting is a mesophilic process utilizing microorganisms and earthworms. Earthworms feeds the organic waste materials and passes it through their digestive system and gives out in a granular form (cocoons) which is known as vermicompost. Like regular compost, vermicompost also benefits the environment by reducing the need for chemical fertilizers and decreasing the amount of waste going to landfills/dumpsites.

Vermicompost is primarily earthworm excrement, called castings, which can improve biological, chemical, and physical properties of the soil. The chemical secretions in the earthworm’s digestive tract help break down soil and organic matter, so the castings contain more nutrients that are immediately available to plants.

Earthworms consume various organic wastes and reduce the volume by 40–60 percent. Each earthworm weighs about 0.5 to 0.6 gram, eats waste equivalent to its body weight and produces cast equivalent to about 50 percent of the waste it consumes in a day. The moisture content of castings ranges between 32 and 66 percent and the pH is around 7.0. The worm castings contain higher percentage (almost twice) of both macro and micronutrients than the garden compost. About 2-3 kg of earthworms is required for 1000 kg of biomass, whereas about 1100 number earthworms are required for 1 m2 area.

There are nearly 3600 types of earthworms and they are mainly divided into two types: (1) burrowing; and (2) non-burrowing. Red earthworm species like Eisenia foetida and

Compost

 are most efficient in compost making. The non-burrowing earthworms eat 10 percent soil and 90 percent organic waste materials; these convert the organic waste into vermicompost faster than the burrowing earthworms. They can tolerate temperatures ranging from 0 to 40°C but the regeneration capacity is more at 25 to 30°C and 40–45% moisture level in the pile. The burrowing types of earthworms come onto the soil surface only at night. These make holes in the soil up to a depth of 3.5 m and produce 5.6 kg casts by ingesting 90 percent soil and 10 percent organic waste.

A wide range of agricultural residues, all dry wastes, for example, straw, husk, dry leaves of crops and trees, stalks, vegetable wastes, weeds etc can be converted into vermicompost. In addition, animal manures, dairy and poultry wastes, food industry wastes, municipal solid wastes, biogas sludge and bagasse from sugarcane factories also serve as good raw materials for vermicomposting.

Enhanced by Zemanta

Different Strategies in Composting

Compost Pile

The methodology of composting can be categorized into three major segments—anaerobic composting, aerobic composting, and vermicomposting. In anaerobic composting, the organic matter is decomposed in the absence of air. Organic matter may be collected in pits and covered with a thick layer of soil and left undisturbed six to eight months. The compost so formed may not be completely converted and may include aggregated masses.

Aerobic compostingis the process by which organic wastes are converted into compost or manure in presence of air and can be of different types. The most common is the Heap Method, where organic matter needs to be divided into three different types and to be placed in a heap one over the other, covered by a thin layer of soil or dry leaves. This heap needs to be mixed every week, and it takes about three weeks for conversion to take place. The process is same in the Pit Method, but carried out specially constructed pits. Mixing has to be done every 15 days, and there is no fixed time in which the compost may be ready. Berkley Method uses a labor-intensive technique and has precise requirements of the material to be composted. Easily biodegradable materials, such as grass, vegetable matter, etc., are mixed with animal matter in the ratio of 2:1. Compost is usually ready in 15 days.

Vermicomposting involves use of earthworms as natural and versatile bioreactors for the process of conversion. It is carried out in specially designed pits where earthworm culture also needs to be done. Vermicomposting is a precision-based option and requires overseeing of work by an expert. It is also a more expensive option (O&M costs especially are high). However, unlike the above two options, it is a completely odorless process making it a preferred solution in residential areas. It also has an extremely high rate of conversion, so quality of the end product is very high with rich macro and micronutrients. The end product also has the advantage that it can be dried and stored safely for a longer period of time.

Enhanced by Zemanta

Composting Guidelines

VACAVILLE, CA - APRIL 20:  Birds fly over a co...
Image by Getty Images via @daylife

It seems everyone is concerned about the environment and trying to reduce their “carbon footprint”.  I hope this trend will continue and grow as a nationwide way to live and not turn into a fad.  Composting has been around for MANY years.  Composting is a great way to keep biodegradables out of the landfill and to reap the reward of some fabulous “black gold”.  That’s what master gardeners call compost and it’s great for improving your soil.  Plants love it.  Check out 10 Rules to Remember About Composting.

  1. Layer your compost bin with dry and fresh ingredients: The best way to start a compost pile is to make yourself a bin either with wood or chicken wire.  Layering fresh grass clippings and dried leaves is a great start.
  2. Remember to turn your compost pile: As the ingredients in your compost pile start to biodegrade they will start to get hot.  To avoid your compost pile rotting and stinking you need to turn the pile to aerate it.  This addition of air into the pile will speed up the decomposition.
  3. Add water to your compost pile: Adding water will also speed up the process of scraps turning into compost.  Don’t add too much water, but if you haven’t gotten any rain in a while it’s a good idea to add some water to the pile just to encourage it along.
  4. Don’t add meat scraps to your pile: Vegetable scraps are okay to add to your compost pile, but don’t add meat scraps.  Not only do they stink as they rot, but they will attract unwanted guests like raccoons that will get into your compost bin and make a mess of it.
  5. If possible have more than one pile going: Since it takes time for raw materials to turn into compost you may want to have multiple piles going at the same time.  Once you fill up the first bin start a second one and so on.  That way you can allow the ingredient in the first pile to completely transform into compost and still have a place to keep putting your new scraps and clippings.  This also allows you to always keep a supply of compost coming for different planting seasons.
  6. Never put trash in your compost pile: Just because something says that it is recyclable it doesn’t mean that it should necessarily go into the compost bin.  For example, newspapers will compost and can be put into a compost pile, but you will want to shred the newspapers and not just toss them in the bin in a stack.  Things like plastic and tin should not be put into a compost pile, but can be recycled in other ways.
  7. Allow your compost to complete the composting process before using: It might be tempting to use your new compost in your beds as soon as it starts looking like black soil, but you need to make sure that it’s completely done composting otherwise you could be adding weed seeds into your beds and you will not be happy with the extra weeds that will pop up.
  8. Straw can be added if dried leaves are not available: Dried materials as well as green materials need to be added to a compost bin.  In the Fall you will have a huge supply of dried leaves, but what do you do if you don’t have any dried leaves?  Add straw or hay to the compost bin, but again these will often contain weed seeds so be careful to make sure they are completely composted before using them.
  9. Egg Shells and Coffee grounds are a great addition: Not only potato skins are considered kitchen scraps.  Eggshells and coffee grounds are great additions to compost piles because they add nutrients that will enhance the quality of the end product.
  10. Never put pet droppings in your compost pile: I’m sure you’ve heard that manure is great for your garden, but cow manure is cured for quite a while before used in a garden.  Pet droppings are far to hot and acidic for a home compost pile and will just make it stink.

Contributed by Roxanne Porter whose original blogpost can be viewed at http://www.nannypro.com/blog/10-rules-to-remember-about-composting/

Enhanced by Zemanta

Composting

Composting
Image via Wikipedia
VACAVILLE, CA - APRIL 20:  Birds fly over a co...
Image by Getty Images via @daylife

The composting process is a complex interaction between the waste and the microorganisms within the waste. The microorganisms that carry out this process fall into three groups: bacteria, fungi, and actinomycetes.Actinomycetes are a form of fungi-like bacteria that break down organic matter. The first stage of the biological activity is the consumption of easily available sugars by bacteria, which causes a fast rise in temperature. The second stage involves bacteria and actinomycetes that cause cellulose breakdown. The last stage is concerned with the breakdown of the tougher lignins by fungi.

Central solutions are exemplified by low-cost composting without forced aeration, and technologically more advanced systems with forced aeration and temperature feedback. Central composting plants are capable of handling more than 100,000 tons of biodegradable waste per year, but typically the plant size is about 10,000 to 30,000 tons per year. Biodegradable wastes must be separated prior to composting: Only pure foodwaste, garden waste, wood chips, and to some extent paper are suitable for producing good-quality compost.

 The composting plants consist of some or all of the following technical units: bag openers, magnetic and/or ballistic separators, screeners (sieves), shredders, mixing and homogenization equipment, turning equipment, irrigation systems, aeration systems, draining systems, bio-filters, scrubbers, control systems, and steering systems. The composting process occurs when biodegradable waste is piled together with a structure allowing for oxygen diffusion and with a dry matter content suiting microbial growth. The temperature of the biomass increases due to the microbial activity and the insulation properties of the piled material. The temperature often reaches 65 degrees C to 75 degrees C within a few days and then declines slowly. This high temperature hastens the elimination of pathogens and weed seeds.

Enhanced by Zemanta