Cheap use and throw plastics have replaced traditional glassware, paper bags, and metal utensils. Single-use plastic bags, containers, straws, cups, cutlery, etc. litter our entire landscape, water bodies, and seas. Burning garbage heaps produces obnoxious, pungent, toxic gases and smoke that damages our lungs and internal organs. Left exposed to weathering, these plastics fragment into harmful fine microplastics. Microplastics are now present in the air, water, food, and even in our lungs, blood, body, and brain. Avoiding plastic water bottles, and food containers especially for salty and acidic foods can block a major source of microplastics. We should adopt the 5Rs of waste management sincerely: Refuse single-use plastics; Reduce waste production and resource utilization; Reuse by substituting disposables with reusable items; Repurpose useless items into something useful; Recycle used materials into useful new goods. Cardboard boxes and aluminium foils should be cleaned of all food particles and dried before sending for recycling.
BUILD, DEMOLISH, AND DUMP: Debris from construction sites and demolished buildings are often dumped recklessly on vacant lands, abandoned open mines, dried lakes, and river beds. Broken and defective ceramic tiles and other construction waste materials can be crushed and used as a replacement for traditional aggregates or cement in concrete, or as a precursor for building blocks, or geopolymers (alkaline-activated materials AAMs), an alternative to Portland cement. Co-processing in a cement kiln uses solid waste, used tires, sewage sludge, waste oils, and construction and demolition waste as fuel. The ash and mineral residue form part of the cement clinker. Silicon carbide from ceramic polishing waste can be used as a foaming agent to produce foam ceramics. Preventing hazardous material content will ensure less environmental exposure and safe recycling of construction materials. Some hazardous construction materials like asbestos, PCBs in joints, seals, and thermal insulated windows have been phased out.
MINE, MANUFACTURE, AND SCRAP: Mine wastes, scraps, effluents, and smoke from factories and industries pollute land, water, and air. Strict enforcement of pollution regulations and legal action can force them to reduce environmental and health hazards.
WASTE SEGREGATION IS IMPORTANT FOR RECYCLING: Waste segregation at the source is essential to prevent all waste from landing in a landfill. Moisture compromises the structural integrity of cardboard, making it difficult to pulp and re-create into new cardboard. Wet cardboard needs to be dried before mixing it with dry cardboard. Oil, grease, and food stuck to take-out cardboard boxes are difficult to clean. They bind the cardboard fibres together, hence are difficult to process. If mixed with uncontaminated cardboard the entire batch has to go to a landfill. All organic matter should be separated and composted, with contaminated paper and cardboard and used as fertilizer later. Butter paper and disposable coffee cups coated with silicone, wax, or plastic are incinerated. Recycling plastic conserves petroleum and reduces soil and water pollution by leachates and microplastics.
RECYCLABLE SOLID WASTE: Organic waste, uncontaminated paper and cardboard, wood, glass, metals waste, and aluminium cans, uncontaminated thermo-plastics (PET or Polyester, PVC, polyethylene, Polypropylene (PP), Polycarbonate (PC), Nylon or polyamide, Polystyrene (PS), acrylics, and ABS) are recyclable. PET is lightweight, strong, transparent, and is used in food bottles/jars, and fabrics (polyester). PVC is hard, rigid, a good insulator, and resistant to chemicals and weathering, hence is used in the building and construction industry, for wire & cable insulation, and in IV fluid bags, medical tubing, and oxygen masks. High-Density (HDPE), Low-Density (LDPE), and Linear Low-Density (LLDPE) Polyethylene, have multiple uses. HDPE is strong and resistant to chemicals and is used for food and beverage containers, bottles, crates, pipes, and cutting boards. LDPE is softer, clearer, and more flexible and is used for cling wrap, bread bags, bubble wrap, garbage bags, grocery bags, and beverage cups. LLDPE is flexible, has high tensile strength, and good puncture resistance, and is used in packaging, construction, and manufacturing. Polystyrene or Styrofoam is used as cups, takeout food containers, packaging, cartons, cutlery, and building insulation.
RECYCLING SOLID WASTE: Material Recovery facilities sort recyclable non-biodegradable dry waste. Recycling units then turn waste into usable raw materials. Non-recyclable, non-biodegradable combustible fraction of waste having a calorific value exceeding 1500kcal/kg is supplied as refuse-derived fuel (RDF) feedstock to solid waste-based power plants or cement kilns in India as per the guidelines of Swachh Bharat Mission. The Solid Waste Management (SWM) Rules, 2016, in India, allow for the treatment and disposal of non-recyclable, non-biodegradable waste with a calorific value of less than 1500 kcal/kg, through sanitary landfills or applicable specified guidelines. Glass can be recycled endlessly by cleaning, crushing, blending, and melting it together with sand and other starting materials. A ton of glass recycled saves about 580kg of CO2, reducing air pollution by 20% and water pollution by 50%. Glass recycling is challenging due to cost and operational difficulties, including breakage, contamination, and high transportation costs, leading to its exclusion from some recycling programs.
RECYCLING PLASTICS: Commonly recycled plastics are PET, HDPE, and PP. PVC and polystyrene are dangerous plastics that can easily leach harmful toxins such as lead, dioxins, vinyl chloride from PVC, and styrene (a neurotoxin) from polystyrene into food in containers made with them. Specialist facilities are required to recycle PVC, LDPE, and PS. Specialized machines can separate the plastic and aluminium components of blister packs. Composites like CDs and DVDs have a clear plastic polycarbonate substrate, a reflective metallic layer (aluminium, gold, or silver), and a thin protective layer of acrylic or lacquer that need specialized recycling. Bioplastics are biodegradable. Recyclable mixed thermoplastics require meticulous sorting according to their resin type since most of the thousands of chemically distinct varieties of plastic cannot be recycled together thus recycling can be very expensive. In mechanical recycling, the plastic is washed, ground, melted, and moulded into a new object. In chemical recycling, the plastic is broken down into monomers to form new polymers to be reused. Recycled plastic degrades each time it is reused, and can generally be reused once or twice only.
NON-RECYCLABLE SOLID WASTE: Plastic-coated wrapping paper, cling film, plastic food packets, and bags, composite plastic like tetra packs and blister packs and polycarbonate, Rexene, rubber items, packaging especially Styrofoam and Thermocol, fabrics and clothes are difficult and expensive to recycle. Thermoset plastics like epoxy, silicone, polyurethane, and phenolic resins form irreversible chemical bonds and cannot be recycled. Energy from the incineration of plastics is not permissible as it releases harmful gases. An estimated 91% of plastics aren’t recycled, ending up in landfills or the environment, due to complex compositions, lack of infrastructure, and economic considerations. Plastic can take hundreds of years to biodegrade, in landfills and pollutes for longer.
HAZARDOUS WASTE: Paint, scrap batteries, mercury thermometers, tyres, broken glass and mirrors, light bulbs, electronic waste, expired medicines and medical waste, and other hazardous materials require special handling and disposal. Scrap electric & electronic appliances, cars, and machinery are recycled to recover valuable materials. Sewage sedimentation or settling tank allows suspended solids to settle as sludge at the bottom for later removal, treatment, and use as fertilizer or for soil amendment (improving soil quality for plant growth).
SOLID WASTE MANAGEMENT: Solid waste management involves the collection of residential, slums, settlements, commercial, and institutional garbage, industrial waste, construction and demolition debris, agricultural waste, timely transportation, efficient treatment, and safe disposal by composting, incineration generating energy, recycling or landfilling. Waste-to-Energy is converting waste into usable energy through various processes like combustion, gasification, or anaerobic digestion. Efficient and safe solid waste management protects the environment and public health, conserves resources by recovery and reuse of valuable materials, and has economic benefits such as waste management jobs and reduced costs of pollution mitigation and healthcare.
PREVENTION, AND MOTIVATION: Engaging the public in waste management efforts through education, awareness campaigns, and participation in recycling programs is essential. Adequate waste collection, treatment, and disposal infrastructure is crucial for effective management. Strong regulations and effective enforcement mechanisms are necessary to ensure compliance with waste management standards.
Dr. P.S.Venkatesh Rao is Consultant Endocrine, Breast & Laparoscopic Surgeon, Bengaluru.