The ABC of waste collection

Advances in bags and containers What are the options for temporary storage of waste prior to collection or treatment? The design of the waste container is a vital aspect of waste handling and a valuable tool in promoting source separation. Designing a receptacle to hold waste prior to its treatment and disposal might sound like the simplest stage of waste management, with far more complex issues to be faced further downstream. Yet we should not overlook the growing range of solutions available for containing waste, with innovative designs and informed strategies contributing to a more sustainable infrastructure. Let¿s first consider the role played by bags. A recent report from the ISWA working group on transport and collection states that bags offer high collection performance and avoid the need for special-purpose vehicles. However, bags tend to provide low levels of comfort for the user and, importantly, themselves increase the amount of waste being discarded. Furthermore, bags conventionally place high physical strain on workers and have to be opened at the sorting plant. "There is scope for demanding more from your bin bag¿ HOW A BAG AND MODERN WASTE MANAGEMENT TECHNOLOGY INTERACT ...Can bags be made to work harder? This may sound like a strange question, but there is scope for demanding more from your bin bag. New materials are lessening the environmental impact of bags and new answers are emerging to support effective bag opening and the separation of different waste streams. What¿s in your bag? Making bags biodegradable is an important development in environmental terms, particularly for handling biowaste. A leading company in the distribution of 100% biodegradable and compostable products is PolarGruppen AS ¿ or since 1 January 2006, BioBag International AS. Its BioBags are made of a material called Mater-Bi¿, the main component of which is cornstarch. This material allows the bag to "breathe¿ ¿ reducing the weight of its contents by up to 20% over five days ¿ and to biodegrade after 10¿45 days depending on the composting method used. BRT¿s technology enhances the efficiency of the bag-opening process An alternative biodegradable bag is made by EcoSack, part of the Korsnäs Packaging Group. This company supplies biodegradable paper sacks for the collection of garden, kitchen and paper waste. According to the company¿s new website, the sacks range from the 8-litre kitchen bin liners through the 75-litre garden and paper waste to the 240-litre wheelie bin liners. Differing paper specifications are used to ensure that the sacks fully meet the specific recycling requirements. What about making plastic bin bags from recycled products? In California, plastic bin bags sold by local bag manufacturers must contain a quantity of recycled plastic post-consumer material (RPPCM) equal to at least 10% of the weight of the regulated bags. Alternatively, at least 30% of the weight of material used in all of the manufacturer¿s plastic products must be RPPCM. However, manufacturers have indicated that the potential for recycling in this way is limited by poor availability of post-consumer resin that meets their quality standards and is compatible for use in their manufacturing processes. Opening up new possibilities Turning to bag handling, if the bag is non-biodegradable, then it must be opened. Companies such as BRT Recycling Technologie GmbH are enhancing the efficiency of bag opening. BRT¿s new bag opener model Schlitz-O-Mat MSW 1-21 can open 40 tonnes/hour of bags containing heavy household waste. The machine has already been launched successfully in Italy and more machines are destined for operation in the United Arab Emirates early this year. Optibag in Sweden breaks open its bags with EnviFlex technology, which tears the material into approximately 35¿50 mm pieces. Thin and leathery materials such as plastic bags remain relatively large and can then be separated on a screen. The additional key element in Optibag¿s approach is that optical sorting technology is used to differentiate different waste streams by the colour of the bag into which the waste is placed. As a result, greater recovery is possible during the handling process. Stefan Holmertz, Optibag¿s Managing Director, commented: "Bags offer low-cost logistics; they help to teach source separation, improve environmental conditions for workers and promote recycling¿. WASTE CONTAINERS AND SOURCE SEPARATION There are various advantages to using more rigid containers in collection, according to the ISWA report. These include high performance, enhanced hygiene, greater variety and an accepted basis for a collection fee system. However, the disadvantages perceived include high initial investment costs and a need for maintenance and special training for workers. Case Study: the Compostainer SSI Schaefer was one of the first companies to develop and manufacture the wheeled bin system of refuse collection over 30 years ago. Today, the product range includes bins from 120-litre capacity to 8.0 m3, and the company¿s products can be found all over the world.Compostable "green¿ and kitchen waste can prove difficult to handle, particularly when there are long gaps between municipal collections. Concerns about odour and hygiene can arise quickly. To address these concerns, SSI Schaefer developed the "Compostainer¿ bin. Efficient ventilation of the bin enables the contents to remain aerobic. Ventilation is achieved through spacer ribs inside the body, ventilation holes in the body and lid, and a grating in the bottom of the container. Maintaining aerobic conditions enables the composting process to begin as soon as organic waste is placed in the bin. This results in a rise in the temperature within the bin and a weight loss of up to 13% of the bin¿s contents due to water evaporation. Temperatures of more than 50°C have been reached and this results in maximum aerobic decomposition of the material and the inhibition of the development of maggots and flies, according to the company. Furthermore, a pH of 7.6 can be achieved, which eliminates the unpleasant smells that can occur with pH values of 5 or less. The bin has already proved highly successful, particularly in Germany, France, Canada and the US. Cities and regions worldwide continue to implement new initiatives promoting source separation, and container design is an important aspect of this strategy. Since different wastes exhibit a wide range of characteristics, it is not surprising that containers are modified to suit the waste being collected. Interestingly, multi-material containers for paper and plastic waste have been introduced in many cities to reduce the number of containers on the city streets but, generally speaking, one type of container is designed specifically for one type of waste. Container design is an important aspect of strategies to promote source separation WASTE CONTAINERS AND COMPACTION Having recognized the value of designing the container with a specific waste stream in mind, it is also important to consider the need to optimize the space available. This means compaction. Developments in the field of waste compaction offer support for municipalities keen to optimize their waste collection services as well as reduce transport costs. There are various options available. In the US, two recent examples are BigBelly ¿ a cordless, solar-powered waste compactor from the Seahorse Power Company ¿ and the Tornado Trash Can from the Greenshift Corporation. The Tornado Generator technology accelerates compressed air to supersonic speeds in a closed cyclonic chamber. The company claims the air is powerful enough to grind, flash-desiccate and atomize solid and liquid wastes almost instantly into micro-size powders. The product line is designed to reduce the volume of waste shipped off-site by up to 90%. In Europe, containers with compaction facilities are also emerging for public use. Examples include Ecology¿s éureka, which is small enough to be used for household waste compaction, and the Superlizzy from CMS SpA, Italy. The Superlizzy, which is being trialled in a fast food restaurant chain, is equipped with an opening automatic door for waste introduction. The inserted material is then compacted, solid waste is collected in a plastic bag, and liquid waste is sucked into an adjacent tank. CMS SpA believes that its approach satisfies the customer ¿ not least in enabling the clean disposal of potentially "mucky¿ food and drink waste ¿ and benefits both the businesses employing this technology and the local authority responsible for waste collection. What colour is your bin? According to the ISWA report, "Overview of Household Collection Systems in Different Cities and Regions¿, there is no universally accepted colour code to differentiate various waste streams (see Table 1). It recommends developing an internationally standardized approach. TABLE 1. The colours of waste containers in different cities. SOURCE: ISWA \t\t A new creature in London Zoo The merits of such an approach are obvious but, as an aside, one wonders how such a scheme would cope with the growing trend to make waste containers more decorative. An example is the ACM Waste Management plc compactors supplied to London Zoo, which are painted in a giraffe pattern and designed to handle over 10 tonnes of animal dung ("zoo poo¿) each week. GOING UNDERGROUNDThe need for compaction is particularly apparent on our busy streets, but what if you look beneath the surface? A growing movement in waste collection is happening beneath our feet. A growing movement in waste collection is happening beneath our feet.Starting literally at the tip of the iceberg, one can consider the Sulo "Iceberg System¿ of galvanized steel waste collection containers, which are available in 3, 4 and 5 m3 modules for storage within an underground pit lined with watertight, reinforced cast concrete. All that is visible at ground level is a steel walkway platform with an integral compact receiver unit through which the refuse is deposited. The system can be used to collect recyclable glass, plastics, paper and cans. To empty the system, a crane mounted on the collection vehicle engages with concealed hooks at the top of the receiver unit which is then lifted, complete with platform and container. The contents of the container are emptied into the collection vehicle through base flaps activated via the crane lift mechanism. "The Iceberg is infinitely more attractive, cleaner and tidier than the freestanding bins or skips that are usually used in recycling bring sites,¿ said one user. Superlizzy compacts fast-food waste at the source of separation Adding an extra dimension to underground waste containment is the Gaia system from northern Italy, which consists of a platform holding eight 800-litre bins, standing on a rotating base that places the appropriate waste bin below the disposal column. Users activate the system with a personal ID card by selecting the type of waste they intend to deposit. The waste is then weighed and compressed, with compression applied to one waste type at a time (organic waste and glass do not require compression). Software communicates the state of the system to a service centre. This approach is intended to enable citizens to pay only for the differentiated waste they produce. By switching from a taxation system to a tariff one, states Gaia, city administrations will be able to incentivize citizens to optimize their waste collection. On an even larger scale, it is possible to install an underground network of pipes for waste collection. This concept is potentially a step toward treating waste removal as a utility, akin to removal of wastewater sewage, or the supply of water, gas and electricity. Two key players in this field are Envac and Oppent. Almere in the Netherlands has become the first city in the world to connect public litter bins to an underground collection system in its centre, thereby collecting street litter and conventional municipal waste in three separated fractions. The technology has been supplied by Envac, a Swedish company responsible for 600 underground installations across Europe and Asia. Users insert waste into a hatch. The waste is then contained temporarily in a chamber, to be released at regular intervals into a network of pipes connecting to a central collection station. The waste is transported via suction, enabled through the management of air pressure in the pipe system. According to Jonas Törnblom, Marketing Director, blockages are rare and only a few times a year do blockages need to be cleared manually. "If the air velocity goes down suddenly, we know there is a blockage. The fans (used to create suction) are automatically stopped and restarted at a higher speed. This normally clears the blockage. In the rare cases when the blockage is not cleared by this operation, an alarm is sent to the service organization and the blockage is cleared manually at the inlet or via a manhole¿. Oppent offers a similar system. The whole process is completely automated through electronic monitoring systems that control and set all operations. The system can be arranged to encourage sorting, whereby the user is faced with different hatches for different waste types. Oppent is currently focusing on the healthcare sector, but the company expects this technology to be adopted more widely in city areas in the future. Oppent serves a small community THE IMPACT OF CONTAINER DESIGN So what is the impact of this growing range of solutions? Here are a few examples where high- and low-tech container design has affected recycling activity or reduced the financial burden of waste processing: Cascade Engineering In September 2005, following a successful trial in Philadelphia, US, Cascade Engineering launched a waste container equipped with electronic tags that transmit key data on the container¿s use to sanitation personnel. While this information is primarily used to optimize waste collection, the data can also be used to reward recycling activity. Preliminary results have shown overall participation rates at more than 50%, with rates as high as 80% in some neighbourhoods. Henkel New on the UK market through Recwaste is the roundbottom bin from P. Henkel GmbH. According to Henkel, containers with hemispherical bottoms are a true innovation for the waste disposal market. The rounded form ensures that the container is emptied completely with optimum results. At the same time, the container is self-cleaning on account of the waste being pushed out by the emptying/rotating movement. It is claimed that municipalities can save up to 20% of their disposal costs on account of faster emptying. The Gaia collection system Valpak Valpak in the UK has found that its rescape¿ bin has had a positive impact on recycling rates. "Rescape banks aim to change the recycling landscape by making recycling more user-friendly for the both the public and the operators,¿ explains Nicola Jones, rescape business manager. The rescape banks were launched in 2004 and are already making an impression in Glasgow, Sheffield, Canterbury and Rhyl. According to Valpak, feedback so far has been positive: footfall (the number of people using banks) increased, with almost 20% of visitors to the banks saying they had not used the previous facilities the amount collected has increased, doubling in some waste streams, with glass, plastic and textiles greater than expected less fly-tipping has occurred around the banks as a consequence of their smarter design. Molok Oy In Finland, Molok Oy has teamed up with a nationwide paper collection company, Paperinkeräys Oy, to increase the amount of paper reclaimed to 75% in two years. Their goal is to make Finland the world¿s leading country in the recycling of paper and they hope that Molok Oy¿s underground waste collection technology will help them to achieve this. Envac¿s underground approachTaylor Taylor has joined forces with design agency Tonic Wonder Remedies to use street art to help increase recycling rates. Based around the Taylor 1280-litre Continental container, the Friesian-cow-style finish has a serious message that will later be aimed at schools to encourage recycling at an early stage. Patricio Forrester of Tonic explains: "Cows are seen as friendly animals and the principal of rumination and its production of milk are positive examples of recycling.¿ Reverse Vending Corporation The importance of education is resonating within other companies too. Reverse vending machines (RVMs) available through the Reverse Vending Corporation are automated machines that utilize advanced technology to identify, sort, collect and process used beverage containers. RVMs are used in markets that have deposits on beverage containers; they offer an efficient method of identifying the deposit amount for each container returned and providing a refund to the customer. The Reverse Vending Corporation states it is the first UK company to provide this technology to the UK education sector. In terms of functionality, the recycler places the empty bottle, can or vending cup into the receiving aperture. The recycler is guided through this process by instructions illustrated on the RVM colour monitor and then receives an incentive voucher, which is dispensed automatically. The security-printed voucher can be used to introduce original incentive schemes. For example, schools have also used these incentive vouchers to reward good behaviour and homework handed in on time. Smart card technology can also be used. CONCLUSIONSWe are continuing to generate more waste. As noted in the ISWA report, the target in Europe of stabilizing household waste generation at a level of 300 kg/year/person has clearly been missed. In many countries, the necessary decoupling of economic growth and waste generation has not yet taken place and the ISWA study suggests that collection systems must be flexible enough to master rising waste streams in the future. While container design is evolving, the most sustainable way to tackle the increasing amount of waste is to reverse the trend and decrease the amount of waste being generated. Guy Robinson is Commissioning Editor of Waste Management World.e-mail: wmw@jxj.com