Construction waste involves construction, roadwork, and demolition materials, as well as complex waste such as plastics, metal, ceramic, and cardboard. Construction materials including wood, shingles, asphalt, concrete, and gypsum make up more than half of the construction waste produced annually.
‘Reduce, reuse and recycle’ policies are required to regulate the amount of building waste, but inadequate funding, lack of standardisation, thin profit margins, political apathy and lack of awareness on the issues prevent this from occurring. The Asia-Pacific region is projected to produce a majority of building waste in the coming year, followed by North America.
Construction and demolition materials consist of debris created during construction, home renovation contractors, and demolition of infrastructure such as buildings, roads, and bridges. Heavy and bulky materials like the following are some examples of construction and demolition materials. The construction sector is struggling to find suitable building materials for the booming cities in Asia and businesses are now vying for toxic waste to replace some of the resources they use, experts claim.
Land reclamation in Lantau
The artificial reclamation scheme for the island of Lantau in Hong Kong does not rely on imported sand but rather will use local building waste. The scheme involves the development of 1,700 hectares of artificial islands off the island of Lantau in west Hong Kong, through sea reclaim.
Construction waste will be a major component and will shape a significant percentage of fill rather than sand. Each year Hong Kong generates 15 million tons of building waste, enough to restore 60 hectares of land, he added. Building waste was also used for the reclamation of the third runway at the Hong Kong International Airport.
Illegal dumping in China
The Shenzhen landslide that collapsed nearly 40 buildings highlights the difficulties that China faces as it digs and constructs subway networks and underground facilities to handle construction waste.
The tragedy was blamed for the illegal dumping of building soil that locals say has gone on behind the Hengtaiyu industrial park in the city for two years. Chinese media reports have highlighted that since 2008, when the city started constructing a network of subway lines, finding places to dump constructing waste soil in coastal Shenzhen was a problem.
Although the problem for Shenzhen, which has small land in comparison with Beijing or Shanghai, is more severe, construction waste is a problem for all China. The situation is worsened by the rush of Chinese cities to create subway lines, which contain more soil waste than normal buildings. At least 38 cities are expected to have one subway line by 2020.
Underground dumping grounds
Cities even tend to go underground as land gets scarce. Hubei’s Wuhan has started constructing the largest underground city in China, announced yesterday by a Chinese state news agency.
According to one state media study, in northern Jinan, less than half of waste dumps have enough capacity to take in construction waste. Since the cost of operating a proper dump was high, it said that illegal ones flourished. After the tragedy Shenzhen stepped up assessment of other dump sites.
Processing waste into construction materials
The Ministry of the Environment and Water Resources (MEWR) in Singapore will soon begin a field trial to evaluate the real-life performance of potential NEWSand materials derived from bottom ash incineration (IBA), the thicker and heavier portion of incinerated ash and that derived from slag, the by-product of solid waste gasification.
The initiative was born out of the push of Singapore to solve constraints and create a valuable waste resource. Since two-thirds of Singapore are designated water catchment areas, the agency said the environmental requirements for NEWSand must be sufficiently strict to ensure that the material can be used at any location in Singapore without compromising the water supplies and environment of the country.
NEWSand implementation comes at a time when Singapore is seeking to reduce the amount of waste that is sent to Semakau. At the time, about 2,100 tons of waste were transported daily to the landfill.
We look at the models Asian governments are employing in order to manage crippling levels of waste – a major challenge that has been overlooked for too long.
Rising levels of waste
The world is more waste producing than ever before. Asia Pacific wastes are expected to grow from about 802 million tons in 2016 to 1.1 trillion tons in 20301. The volume of waste has increased rapidly in Southeast Asia alone since 2000, reaching around 150 million tons in 2016. By 2030 the expected sum will be more than double.
We see this happening around us, and feel it happening. Take for example the distribution online. With only a few taps on our smartphones, the introduction of e-commerce made it much easier to get products shipped to our doorsteps. With no understanding of what happens to them after they end up in the landfill, we dispose of the packaging and the leftovers. While some of our waste can be recycled, a significant portion of it will end up in landfills.
Unfortunately, some waste persists for years and makes waste management a serious issue that deserves no less attention than the likes of eliminating poverty and climate action. Poorly handled waste will result in far too serious consequences to bear. Solid waste clogs rivers, exacerbates flooding and encourages vector breeding. Waste builds up in nature, washes out and contaminates rivers and ultimately ends up in the oceans. Open burning releases toxic pollutants and respiratory related allergens. Landfills take up considerable land space and, in many cases, may not be viable in the long run.
No wonder that numerous countries have stepped up their efforts to reduce the amount of waste by recycling and handling solid waste better. Many of us are contemplating waste-to-energy (WTE) technologies, such as incineration, which takes solid municipal waste into an eco friendly combustion process and retains the heat value of the combusted waste for steam and electricity production. Second, less waste management to landfills means less methane and other greenhouse gases (methane is more environmentally damaging than carbon dioxide, at least 20 times more). Secondly, energy is now generated from waste instead of burning fossil fuels which further reduces greenhouse gas emissions.
Yet it is not without their difficulties to build a waste treatment facility. Below are just some of the most important considerations when a waste management facility is built.
Selection of the technology would depend on factors such as form of waste, quality of waste moisture and calorific value, regulatory framework and proximity of waste facilities. The technology needs to be defined early, for instance at the pre-feasibility study phase of a waste management project, because selection of technology will affect the project’s viability and bankability.
A basic rule is if the waste has a calorific value of about 6 MJ per kg, it can be classified as WTE using grate-based combustion. In Southeast Asia, the problem with municipal solid waste is that it is mostly fairly wet and thus has a calorific value of below 6 MJ per kg. There’s a few choices for handling this. One may consider pre-treating the waste to extract moisture thus enhancing its calorific value, or simply designing the bunker to remove free water for pre-storage of the wastes. This will be enough in several cases to extract sufficient water to combust the waste.
Biological treatment such as anaerobic digestion or aerobic composting may be considered for very wet waste and waste which comprises mainly organic fractions. The residue from such processes can often be used as a fertiliser, but it can be very difficult to achieve the sanitation necessary for agricultural use, due in particular to micro-plastic and other contaminants. The further separated and cleaner the fractions of incoming waste are, the higher performance can be achieved. Another option is mechanical waste treatment to sort high-calorie fractions of waste to be used as a fuel, typically in cement kilns, called Refuse Derived Fuel (RDF). The challenges facing these initiatives include securing long-term off-take agreements and meeting the high technical demands for RDF quality to be produced. The potential revenue sources provided by the Power Purchase Agreement (PPA) are easier to predict for the electricity-producing treatment methods.
In Southeast Asia where usually the waste fractions are co-mingled, an incineration plant, a mixture of combustion and anaerobic digestion, an RDF plant or hybrid with the other technologies may be considered. In a circular economy strategy, initiatives can often be seen, where waste is recycled to the degree that it is technologically and economically feasible. When deciding the technology, technical advisors must weigh all aspects, including the waste management mechanism and economics, as both of these aspects are interconnected. Eventually, the customer will end up with a good long-term equipment, and a price-effective and safe electrical services customised to local requirements and legislation.
Economic waste considerations
First, if one considers a WTE plant based on incineration, then a minimum amount of waste is required to make economic sense. A general rule is to have at least 500 tons of waste every day – the better, particularly when it is supposed to have low calorific value. This does not mean plants below 500 tons per day will be unfeasible. There are plants with outputs as low as 50 tons per day, such as airport waste management plants, so WTE can be adapted to local requirements, but it may be more difficult to make them bankable.
Second, in the case of a public-private partnership project, the developer in the private sector will need to be told that they would obtain enough waste daily to earn enough tipping fees and have enough waste to generate energy for sale. Developers, after considering the large capital outlay, would unlikely accept risk if the waste provision is unknown. That’s why Singapore’s National Environment Agency (NEA) received just one bid when, in 2001, it first called for a proposal for the fifth WTE plant in Singapore. NEA required the developer to take risks related to financing, architecture, service and demand.
A report was commissioned then, and the proposal was re-tendered in 2005 with improvements in terms of content. One of the biggest improvements was the introduction of the “take-or-pay” strategy, where either the government buys 100 per cent of the developer’s incineration capability or charges a cost to the developer. This means the government must bear “market” risks by providing maximum capacity payment to the manufacturer, irrespective of the WTE plant’s actual usage rate.
The tender had drawn positive business responses, and eventually processed 800 tons of solid waste daily to produce about 22 MW of renewable energy. It is fitted with a single condensing turbine generator with two incinerator-boiler units.
Not all policymakers will be able to follow the “take-or-pay” strategy and bear maximum risk of demand. The WTE plant developer and/or the structuring advisor will need to be innovative in these circumstances and find assured sources of waste and revenue. That can be achieved by, for example, signing waste supply treaties with mills, farms around the WTE facility, or waste collector businesses, and signing off taking agreements with local industries for refuse derived fuel (RDF) and electricity.
Legislation and necessary frameworks
Clear enabling legislation is critical if waste management programs are to get off the ground. Second, specific legislation provides clarification as to how the equipment used and discharges from plants comply with the applicable regulations and pollution requirements, which are vital to developers and funders. Second, legislation requiring higher tariffs to be paid on electricity generated by a waste-management facility would increase its financial sustainability and reduce dependency on tipping fees.
The Philippines has tabled the Waste-to-Energy (WTE) Act, and believes that clarifying the related WTE legislation is a positive step.
First, it demands the incorporation of a WTE policy in the solid waste management strategies of state, regional, and local governments. Furthermore, it offers assurance that WTE plants will be regarded as solid waste treatment facilities and exempted from the prohibition of incineration as long as they follow the pollution requirements set out in the Clean Air Act. Third and more significantly, local government units (LGUs) would be authorised to cluster and enter into long-term contracts, joint ventures, PPPs, and cooperative undertakings to build WTE projects. It not only solves the problem of one LGU not having adequate waste supply for a WTE plant, but also brings the LGUs together to reap efficiency gains.
Vietnam has pushed in the same direction, too. The government has adopted various policies for businesses that are interested in WTE programs. The major regulations provide for the support mechanism for WTE project growth.
The bill deals with investment opportunities and initiatives in different sectors like the building and collection, storage, recycling, and waste recovery in concentrated solid waste storage zones. Vietnam also stipulated tariffs applicable to WTE plants.
Commercial arrangements and structuring
Unlike a water treatment plant where the investment cost based on the generated MLD13 can be accurately calculated, a solid waste management facility is entirely a different ball game. This depends on a variety of variables, such as land-to-country and seasonal waste characteristics, climate, soil, water quality regulations, quantity of waste to be collected, space limitations, and overall solid waste treatment and state support regulations, to name only a few. Waste management is currently heavily based on the PPP and Build-Operate-Transfer (BOT) models, making revenue streams such as tipping fees, feed-in tariffs, and RDF rates, recyclables, and compost vital to successful implementation.
Strong waste management is already a major concern of local governments in South Asia. It constitutes one of their greatest costs and as urban populations increase, the issue increases year after year.
Logistics and space
There are two factors that have a major effect on a waste management system’s expense and feasibility as it relates to collection and transportation: first, the distance traveled between collection and disposal point; and second, the degree to which wet kitchen waste can be kept separate from dry waste, all of which can be recycled. Separating waste in this way ultimately decreases manual processing costs and raises recyclable material rates.
Distances are too big in many larger towns for door-to-door users to dispose of waste directly at the dump site. Arrangements are made for disposing of waste provided by the municipality at the secondary storage points (large skips). Where these are not drained periodically, however, the waste is likely to spread outside the containers, creating a further environmental danger.
Ideally, and if suitable land can be identified, this issue can be avoided by a variety of smaller waste disposal sites scattered around a community. Through major public awareness campaigns on our part, and ongoing regular reminders to homeowners, we were able to lift the household separation rate to about 60%, but as such reminders were less frequent, the rate quickly fell down to about 25%. Across larger towns, the problem is compounded by the unavailability of separate secondary storage containers, and at this stage all is mixed up anyway, given householders’ best efforts.
To maintain levels, long-term continuous and continuing promotion is required. The cost of this needs to be weighed against the financial benefit of cleaner separate waste and decreased cost of sorting. Local authorities play a significant role in helping to encourage healthy, household-level, solid waste management activities.
Limits to composting
Our experience with home composting indicates that complete coverage is very difficult to be reached, for every household using the device. Where we have promoted it extensively and we have seen the regular usage of around 65 per cent of the bins in collaboration with the Local Authority. However, even this level of reporting may have a huge effect on the amounts of waste which need to be collected and disposed of. Around the same time it can provide major, organic inputs to home growing, providing poor householders with a more diverse and healthy diet.
The range of innovations we’ve been showcasing have various benefits and drawbacks. Maintenance is more difficult for others and clogging problems will occur. There is a need for a daily supply of fresh waste which has not already been decomposed for the dry-fermentation chambers. For other water-intensive systems, very large quantities may be needed. All these technological problems can be solved with good operating and maintenance practices, but when choosing the right technology for a given area, considerations need to be considered.
The biggest challenge for producing compost was to achieve daily sales. The compost market is seasonal, generating an erratic cash flow which has to be factored into the business model. In Bangladesh the need for the drug to be legally approved was a major obstacle. Product quality specifications are stringent to ensure farmers purchase a product they can trust.
The need for on-site testing facilities, however, could be too prescriptive, creating a obstacle to these smaller-scale operations. A second tier of license could likely be generated for waste compost which would make selling easier but with lower guarantees for farmers.
Sustainable food production
The idea of sustainable food using compost created from organic waste was very much welcomed by community people. In Sri Lanka, women have been practicing vertical gardening which has become a source of extra income for the family to meet the daily consumption needs.
In Bangladesh, female organic fertiliser entrepreneurs cultivate seasonal vegetables and fruits with compost and produce more quality goods. We offer these goods at higher prices in local and national markets, because this is still the country’s niche segment. To boost and maintain market demand, the healthy food producers need financial and regulatory support from the government and related certification and quality control agencies.
Solid waste management is a field which has not earned the attention it needs from policymakers in the nations of South Asia. This could change with its inclusion in the SDGs and in other INDCs that are the basis of the Paris Climate Agreement. To meet the challenge, we will need new collaboration strategies, and the implementation of different types of systems and technologies. This will require increased awareness and capacity building at the level of the local authority. If national climate or SDG targets are to be met, localisation through municipalities will be needed. An significant part of this would be greater exchange of expertise at the national and regional level through municipal associations, regional bodies and regional local authority associations.
Waste Met Asia
Waste Met Asia