Watching the waste line

Although there has been a delay in UK electrical and electronic waste legislation, effective management in civil engineering is playing a key role in prestige construction projects. Paul Gay reports.As European legislation deadlines draw nearer, the need for waste management and recycling becomes more important.Government plans to transpose the waste electrical and electronic equipment (WEEE) […]

Although there has been a delay in UK electrical and electronic waste legislation, effective management in civil engineering is playing a key role in prestige construction projects. Paul Gay reports.



As European legislation deadlines draw nearer, the need for waste management and recycling becomes more important.


Government plans to transpose the waste electrical and electronic equipment (WEEE) regulations into UK law, originally scheduled for the next few weeks, have now been delayed by six months.



After careful consideration, the government has decided to implement the producer responsibility and retailer takeback obligations in respect of WEEE in June 2006, instead of in January.



The reason for this is that the government wants to ensure that an adequate UK network of facilities for separate collection of WEEE is in place for householders. This is a key practical requirement for the implementation of the directive. While much progress has been made, it is clear that a UK-wide network of WEEE collection facilities will not be ready by the start of next year.



The registration of producers has also been a stumbling block; this is now expected to take place in January and February 2006. The detailed arrangements for registration should now be published this autumn, in order to give producers time to prepare to submit their registrations.



The deferral of producer responsibility may have implications for local authorities due to the Landfill Regulations Waste Acceptance Criteria. These now apply to any waste, including products containing cathode ray tubes (such as televisions and computer monitors) and fluorescent lamps. Such waste may be collected separately and classed as hazardous, then sent to hazardous landfill.



The DTI, DEFRA and the UK environmental agencies will provide guidance to stakeholders and seek to minimise the level of any additional costs. The DTI has undertaken to meet any additional costs to local authorities in relation to this hazardous WEEE in line with the ‘new burdens’ principle and is taking forward practical arrangements for this.



Around one million tonnes of WEEE is sent to landfills in the UK each year, and 85 per cent of the total weight of this consists of IT and household appliances. It is growing at around eight per cent a year, much faster than regular waste, driven by the increasing global demand for new appliances and IT equipment with shorter lifecycles.



The costs of replacing scarce resources must also be considered, with the amount of energy required to extract copper being six times that needed to recycle the same material.



The directive requires producers to meet the financial costs of collecting and recycling WEEE, and encourages them to re-design their products for ease of recycling, and re-use.



WEEE will be separated from other waste streams, with specific targets for recycling in place, and clear responsibilities set out for all stakeholders. Initially, while the costs of affected products may increase, with re-design for easy disassembly and recycling, and good supply chain management, the price increases if any should be negligible.



WEEE is only one small part of waste management. Civil engineering and construction projects generate massive amounts of waste which has to be managed and recycled.



Portable weighing platforms, supplied by industrial weighing specialists Weightron Bilanciai, have been playing a small, yet vital, role during the development of London’s CanaryWharf. The special platforms were incorporated as part of innovative waste recycling equipment developed by Leyton company Bywaters for speeding up waste recycling during the construction of two 45-storey buildings in the heart of London’s docklands, including the prestigious HSBCTower at

Canada Square
.



Processing building waste during the construction and fit-out of multi-storey buildings in confined spaces poses a tricky problem. During the building of the 12-storey Citibank building, waste varying from brick to cardboard was brought down by hoist in 150 wheelie bins. Analysis showed that this took up more than 12 per cent of construction hoist working time. When planning the 45-storey towers, it was clear that moving several hundred wheelie bins up and down would be impractical.



An alternative solution was to use a chute system with entries at each floor. Such a construction needed to be sufficiently robust to handle the weight of the waste and control its speed as it reached the bottom, and designing it needed more than a flash of inspiration.



Bywaters’ solution involved a robust chute system, with two quadrant control gates and a lower deceleration zone. This arrangement slowed down the material before it entered the compaction chamber and the waste could then be pushed into the closed container sitting on the weighing platform.



The platforms are designed specifically to weigh roll-on roll-off type waste containers during filling operations on site. Their robust construction ensures these portable modules can withstand the arduous conditions found at waste sites, building sites and factories.


They are designed to have significant overload capability, in excess of their 30-tonne working capacity, and the steel deck is supported on four 25-tonne capacity load cells. The units are fully portable and have lifting eyes on the side of the platforms. Adjustable self-aligning pads attached to the load cells provide a secure base — even on unlevel ground.



The decks have guide rails along their 6.3m length and a V-shaped end locator. This ensures the precise positioning of the containers as they are off-loaded and lined up with the compactors. The container wheels run along easily replaceable steel strips.



Weighing the containers provides vital information and ensures the containers are filled to their optimum 15-tonne capacity.



Under-filled containers are uneconomical to remove, while overweight ones mean that the waste vehicles are over their legal load limit.



In addition to the standard weigh display, each system is fitted with a klaxon, which sounds if containers continue to be overloaded.


Recycling usually means materials segregation, or screening. Vibratory feeders, both fixed or variable speed, were complimented by vibratory conveyors, all capable of handling large, volumetric and where necessary heavy products. In addition to the ability to feed and convey products, the Rotex range of direct drive and gyratory motion screeners can separate dry product by size, either simplistically or very accurately.



Typical industries where this has been successful include rubber, glass, municipal waste, plastic, ferrous and non-ferrous.



Glass seems to be an ideal screening product as the larger industries and general recycling companies specialise in recovering glass properties for new uses. Sandblasting is becoming more difficult to justify due to the silica content and legislation regarding the percentage allowable in local water treatment systems.



As such glass has become a new acceptable product. Aggregates, building blocks, decorative uses, cement and paint are among the potential uses.