– by Gaurav Tyagi
New Delhi, Sep 11, 2017: Rapid urbanization globally has led to large scale migration of people from rural to urban areas. This has resulted in huge waste disposal problem all over the world.
Ideally, food discards should be returned to the soil. Food leftovers fed to animals and the cattle shed waste put in a pit to decompose. It can then become a very good source for the planting season as NPK (Nitrogen, Phosphorus, Potassium) nutrients and micro-nutrients for the soil resulting in healthy crops.
The advent of plastic has led to a major problem. People throw the kitchen waste in such plastic bags. This mixed waste when put in the fields, results in the non-bio-degradable plastic film preventing the rain from entering the soil and stop seeds from germinating through them.
This assorted mixed waste presents a serious challenge for the city authorities. The municipalities usually dump them outside the city limits thus creating mountains of mixed waste.
These hills of garbage are denied oxygen from the air. They emit methane, ammonia, hydrogen sulphide and produce leachate, a black liquid oozing from the waste; for example, if a rotten tomato is left in the open air, it would dry to powder within days but the same tomato in a plastic bag would turn into a smelly liquid therefore, it is vitally important to aerate the garbage heaps.
Garbage heaps without proper exposure to air take decades to slowly decompose, continuously releasing methane and leachate. This leachate seeps into the soil and contaminates deep natural water channels.
The segregation of waste at source into wet (compostable), dry (recyclable), sanitary (disposable diapers as well as sanitary napkins) and hazardous domestic waste should be made compulsory in every nation.
The city authorities should ensure strict 100% compliance of the aforesaid norms with provisions of strict fines, for residents not adhering to these measures.
Once every household segregates its waste into separate categories, then it becomes very easy for the city councils to pursue scientific garbage management.
The dry waste can go for recycling. The hazardous material disposed of safely.
The food waste collected by the authorities must not be dumped in high heaps instead the pattern of windrows should be followed.
Windrows are long, low parallel heaps of waste not more than two meters high. They are designed to achieve the optimum conditions for aerating the waste.
The dumping trucks unload their waste load in a long row. Enough space is left between rows for a lifting tractor or an earthmover to drive through and periodically turn the waste.
The outer aerated waste forms the inner core of a new window and the airless centre of the old heap goes outside. A weekly turning of the waste repeated 3-4 times ensures that all parts of the waste get fully decomposed like leaves on a forest floor, turning dark brown with a sweet earthy smell.
This process can be further accelerated by adding composting bio-culture like fresh cow-dung. Fresh waste windrows heat up inside to about 55 degrees – 60 degrees Celsius in 3-4 days. After 4 turnings, there is about 40 % weight loss as the moisture content declines and also approximately 40% volume reduction.
After this, no leachate, methane and smelly gases get released. This fully stabilized waste turns into compost, which is rich in microbes as well as humus. Both of which are excellent for soil vitality.
This can be used as organic manure in agricultural fields thereby eliminating the need for chemical fertilizers for farming.
City authorities can ensure long term use of the same landfill site by following this approach for waste processing rather than continuously looking for new waste dumping grounds.
Poor homeless people in the cities can be trained and employed at such landfill sites thereby making them valuable contributing members of the society.
By strictly implementing this course of action globally; governments could easily ensure a healthier, cleaner, pollution-free planet thereby, effectively tackling the menace of ever increasing garbage in an environment- friendly sustainable manner. These measures would also greatly assist in urban poverty alleviation.
The author is a Master Degree holder in International Tourism & Leisure Studies from Netherlands and is based in China