Options for Kerbside Collection of Household Organic Wastes

Acknowledgements

Executive Summary

1 Introduction

2 Issues to Consider When Selecting Kerbside Organic Waste-Collection Systems

3 Assessing and Comparing Organic Waste Collection Systems

4 Conclusions

Appendix 1: Kerbside Kitchen Waste Collections in New Zealand

Appendix 2: Overseas Kerbside Kitchen Waste Collections

References

2 Issues to Consider When Selecting Kerbside Organic Waste-Collection Systems

This section outlines the issues that a council should consider when selecting a kerbside organic waste-collection system. These include:

• the household organic waste diversion targets that need to be met
• the type of waste to be collected
• whether bags or bins will be used, and which size of bin is appropriate
• the capacity and type of waste treatment facilities available
• the capital and operating costs of the collection system
• any operational constraints (eg, health and safety considerations, multi-tenanted dwellings)
• the markets for the compost produced
• the frequency of collection (eg, climate considerations)
• the ability to monitor the system (eg, conduct household surveys, waste audits)
• householder co-operation
• convenience
• whether the scheme will be voluntary or compulsory.

Sections 2.1 to 2.8 address these issues using the case studies appended to this paper by way of example (see Appendix 1 and Appendix 2). Examples of two collection systems are outlined in section 2.2.3.

2.1 What will be collected?

A kerbside collection system needs to provide for the types of household organic waste that may be collected, which will in turn depend on diversion targets and the acceptance criteria of the treatment facility.

To maximise diversion of organics from the municipal waste stream, collection of both kitchen waste and green waste would be required. Aside from land-filling and incineration [New high-temperature hazardous waste incinerators have been banned as a method of waste disposal by the Resource Management (National Environmental Standards Relating to Certain Air Pollutants, Dioxins, and Other Toxics) Regulations 2004.] , anaerobic digestion is a feasible treatment for kitchen waste and green waste, with its associated benefit of biogas production for energy. Outdoor, in-vessel or vermiculture composting as well as anaerobic digestion may be used where kerbside organic waste collections only cater for kitchen scraps and green waste. These options still provide for substantial diversion of organics from landfill.

2.1.1 Separate or combined collection of food waste and green waste?

Options for collecting green waste and/or food waste are:

• collecting food waste only
• collecting green waste only
• collecting both food waste and green waste but in separate containers
• collecting combined food waste and green waste.

The combined option was most common in the kerbside collection schemes investigated for this desktop study, basically because this system increases the yield of organic material collected/diverted and only one collection receptacle is required. It is also more user-friendly to collect both waste streams together, saving time for the user and potentially helping to reduce odour and leachate from the food waste.

However, possible drawbacks of this approach are:

• the potential economic impacts on existing private green-waste collection operators, through loss of revenue
• less control of the material mix at the treatment plant compared with separate green-waste and food-waste collections, or only collecting food waste
• the ratio of food waste to green waste may vary substantially between seasons, affecting the material mix at the treatment plant
• a secondary system for food-waste collection may be required from properties where there is no green-waste generation (eg, apartment dwellings).

2.2 Kerbside organic waste-collection systems

2.2.1 Food-waste handling

The URS report on food-waste market issues identifies the following ways that residents can manage handling food waste before it is collected (URS New Zealand Ltd, 2004b: 9.2):

• place kitchen waste in a small kitchen bin, which is supplied by either the householder or the collection provider, then transfer to a larger outdoor bin when full
• wrap the food waste in newspaper (this improves handling and helps control odour and leachate)
• freeze the food waste until collection day (this also improves handling and helps control odour and leachate).

2.2.2 Bins or bags?

The two main receptacle options for organic waste collection are bins (typically mobile garbage bins - MGBs) and bags. Each has its own advantages and limitations. The URS report on food-waste market issues (URS New Zealand Ltd, 2004b: 9.3) identified the following issues.

• Mechanical collection is possible for MGBs, whereas bags require manual collection. Manual collection can improve detection of contaminated organic waste, but has more associated health and safety issues.
• Bags as bin liners reduce cleaning requirements, odour potential and spillage. They may be made of paper, biodegradable corn starch or non-biodegradable plastic. However, they are an additional cost and may require distribution to householders.
• Bags for use at kerbside are a lower-cost system than bins, but they can have a higher cost and/or more complex administration. Bags used without bins are more susceptible to animal strike and may need to be split open and removed at the waste-treatment facility. This can increase the risk of contamination of the end product.
• MGBs come in a variety of volumes to meet different capacity requirements but, like plastic non-breathable bags, can cause accumulation of odours and leachate if not used correctly. Aerated MGBs are designed to alleviate these problems.

Paper bags used as bin liners have been found to have the following benefits (see also Appendix 1[c]).

• There is less accumulated odour due to greater exposure to and diffusion by air (oxygen).
• Collection frequencies can be reduced due to reduced accumulated odour.
• There is greater weight reduction of organic waste due to greater evaporation rates.
• Paper bags do not have the same contamination issues as plastic bags when fed into an organic waste-treatment facility.
• They are user-friendly, with a reduced need to rinse bins as leachate is partly absorbed by the paper bag.
• Bags can have information printed on them.

Biodegradable corn-starch bags used as liners have been found to have the following benefits (see also Appendix [a]):

• 100% biodegradability and compostability (so long as the required temperature and moisture requirements are met)
• completely biodegraded after 10 to 45 days, depending on the composting method (so long as the required temperature and moisture requirements are met)
• moisture reduction in food wastes
• odour control
• bags can have information printed on them.

2.2.3 Systems for kerbside organic waste collection

Detailed case studies of several collection systems are presented in the appendices. This section summarises two of these case studies as examples to illustrate how these quite different collection systems have been designed. The systems are operated by Lismore City Council (New South Wales, Australia) and Mackenzie District Council.

The Lismore City Council combined food-waste and green-waste collection system has been operative for more than five years (see Appendix 2[a] for details). The council supplies 120 or 140-litre MGBs for weekly organic waste collection. Residents are expected to provide their own kitchen tidy bin, wrap their food waste in newspaper and rinse out their MGB. This approach is currently being trialled by Christchurch City Council (Appendix 1[a] for details), although kitchen bins are being provided for convenience and also as a way to educate residents on what they can recycle via a sticker on the bin.

Residents in the Mackenzie District Council's collection areas pre-purchase non-biodegradable plastic bags for their food waste and green waste (see Appendix 1[b] for details). These bags are manually split open at the resource recovery centre to allow the organic waste to be fed into the in-vessel composting system. Households are not provided with a kitchen tidy bin.

Some more sophisticated kerbside organic waste-collection systems use a combination of an MGB, kitchen food-waste bin and either paper or biodegradable bags (see Appendix 1[c] for details). These systems consist of a kitchen container specially designed to maximise airflow around the bag (maintaining the waste's exposure to oxygen reduces odour and water content). Once full, the kitchen bag is placed in a flip-top MGB, which is also designed to promote air flow around the waste. The bin is then placed on the kerbside for collection. Because specially designed containers are provided, these systems are expected to be more expensive than standard MGB or bag systems.

2.2.4 Organic waste collection systems for multi-tenanted dwellings

Flats, apartments and other multi-tenanted dwellings need special consideration for recycling services, because space on the kerbside is more limited and environmental impacts such as odour and leachate from putrifying organic wastes may be more significant.

The United Kingdom's Department for Environment, Food and Rural Affairs (DEFRA) commissioned Waste Watch to "produce case studies of recycling and composting schemes in housing areas where design, layout or management considerations make the provision of conventional kerbside collections difficult or inappropriate (for example, flats in estates and high-rise blocks)" (Waste Watch, 2004: 4).

These case studies, although not always specific to organic waste collections, should be considered as part of any investigation into the provision of recycling services (including organics) to multi-tenanted dwellings. The key findings of the study, covering 16 local authorities and three European authorities, are as follows (Waste Watch, 2004: 3).

• A number of different approaches to including flats in recycling schemes have been adopted, including the provision of communal containers at central and near-entrance locations, door-to-door collection and conventional kerbside collections.
• The overriding concern in selecting collection methods for recycling schemes for flats is to provide convenient and secure services at a reasonable cost. There appears to be wide variation in the interpretation of this objective.
• Container location is determined by taking into account factors such as convenience, storage space constraints, other pressures on land space, vehicle access, existing refuse collection arrangements, and acceptability to residents (in terms of, for example, noise, visual intrusion or the potential for vandalism).
• Container choices are influenced by the number of households served, the material segregation arrangements, space availability, bulk purchasing opportunities and vehicle constraints.

2.3 Frequency of collections

It was apparent in the case studies that weekly kerbside collection of organic waste was the preferred frequency, often paired with a fortnightly collection of commingled recyclables and residual waste. The main impetus for weekly collection of organics is to avoid generating unacceptable odours.

Hutchinson City, Minnesota, was able to vary its collection frequency according to season due to having particularly cold, dry winters. Summer collections of household organic waste were weekly but dropped to fortnightly collections in winter (see Appendix 2[c]). Potentially, this approach could be used in the southern parts of New Zealand if the climate is consistently cold and dry enough in winter to keep odour generation from food waste at low levels. Fortnightly collections would be inappropriate in areas of New Zealand that are warmer and more humid.

2.4 Trialling and monitoring kerbside organic waste collection systems

Any kerbside organic waste collection system should be trialled before full-scale implementation to identify any local issues or knowledge gaps. The results of such trials can be used to design the final kerbside organic waste collection service in a way that manages any local effects. Another option is a staged implementation of the collection system to iron out any problems, although detailed research on the type of system is still required beforehand.

The ability to easily conduct waste audits and household surveys should also be considered in the design of any kerbside organic waste collection system. This is particularly important if a key driver for implementing a separate organic waste collection is to meet targets for reducing wastes to landfill, because without the means to easily collect data on waste diversion rates the success of the trial cannot be measured. Similarly, reliable local waste collection data are required before a separate organics collection is introduced.

Key factors you should take into account in the design of a food-waste collection trial are:

• factors affecting the participation rate (see following sections)
• operational issues (eg, in-house and kerbside containers, collection efficiency, odour, consideration of appropriate services for multi-tenanted dwellings)
• contamination (what is considered to be contaminants depends on the intended method of treatment for the organic wastes)
• diversion rates (eg, the rate of domestic composting, seasonal influences).

Christchurch City Council, North Shore City Council and Timaru District Council have all undertaken kerbside organic waste collection trials. These examples are detailed in Appendix 1.

2.5 Participation and contamination rates

High levels of participation by householders can be encouraged through:

• well-defined communication plans implemented before the trial through local community networks, including schools, community boards, residents and ratepayers groups
• ensuring convenience (ie, minimising the effort required to separate wastes)
• minimising the cost to the householder, and/or charging more for residual wastes and less for separated wastes
• ensuring the collection system is easy to keep clean
• special incentives to promote participation in the trial.

Contamination can be managed or reduced by:

• visual assessment by waste collection staff at the kerbside (eg, leave contaminated bins uncollected)
• separation at the waste-processing facility
• householder education, such as leaving householders a "contamination card" following kerbside audits.

The kerbside organic waste collections and trials reviewed for this study are characterised by very high levels of participation (usually greater than 85%) and very low levels of contamination once the service has been established (usually lower than 5%). The exception was the Australian Capital Territory 10-month trial (see Appendix 2[a]), where participation of greater than 90% and low contamination of 1.3% was encountered for the first five months, after which both participation and contamination declined markedly in the second half of the trial. North Shore City Council (see Appendix 1[d]) found in their kerbside organic waste collection trial that contamination was "relatively easy to detect" (North Shore City Council, 2003: 5).

2.6 Voluntary systems or legislation?

None of the municipalities considered in this paper have a bylaw prohibiting residents from putting organic waste in their residual rubbish. In other words, the organic waste diversion schemes are voluntary at the household level. The difference between the participation, yields and contamination rates in municipalities that require segregation compared to those that use only voluntary measures are not known. This outcome confirms that a voluntary approach may be an appropriate mechanism for achieving separation of organic waste at the household level.

In some countries, especially Europe and North America, compulsory targets for waste diversion from landfills, or landfill bans on organic waste, are set out in legislation. In these cases responsibility for meeting targets or preventing organic waste from entering the landfill generally rests with the municipal authority or landfill operator. This means that source separation of organic waste by householders is not compulsory. [See the following internet sites for information: Italian and Dutch management of organic waste, see country reports at European Compost Network http://www.compostnetwork.info; New Brunswick, Canada, Waste Reduction and Action Plan, http://www.gnb.ca/0009/0372/0005/0001-e.asp]

Because there is currently no proposed national legislation to require the separation of organic waste, and because there are limits to the availability of processing systems and composting markets, voluntary systems that combine householder education with other mechanisms (eg, direct service options and economic incentives) may be an effective way to get participation in kerbside food-waste collection schemes in New Zealand. However, this does not rule out introducing bylaws prohibiting organic waste in council-collected household refuse if circumstances change. A locally regulated approach would have to be considered on its merits at the time if the voluntary approach was not working.

Issues to take into account in this case would be:

• the design and implementation of an enforcement regime
• the existence of an adequate range of service options, such as home composting, kerbside collection or drop-off centres
• perverse outcomes, such as householders switching from public to private waste collection if the bylaw only applies to public waste collection
• the legal implications of a bylaw applying to private waste contractors.

2.7 Householder education

The content and type of household education and/or informational material that would accompany the introduction of a kerbside organic waste collection scheme will depend on the option chosen. The URS report on food-waste market issues (URS New Zealand Ltd, 2004b: 9.4) recommends that information presented to residents should include:

• the reasons for providing the organic waste collection service
• the environmental benefits of composting
• instructions for the use and storage of collection receptacles
• a list of acceptable and unacceptable wastes for collection
• instructions for handling food waste
• collection details - frequency, day, placement of kerbside receptacle.

Informational material could take the form of brochures, letters, stickers or fridge magnets. Councils may also want to consider how to expand their marketing beyond direct householder information leaflets and consider alternatives such as presentations and demonstration sessions through local community networks.

2.8 Market issues

Section 2.1 notes the issue of investigating the impact of a publicly operated kerbside collection for organic waste on existing private green-waste collection operators. Other market and economic matters associated with the implementation of kerbside organic waste collection include:

• the extent to which householders would switch to private waste-collection services if a bylaw was introduced prohibiting organic waste in residual household waste, and how this could potentially be remedied through legal or economic instruments
• the development of a suitable market for the compost produced from organic waste collected at the kerbside
• the cost of providing a collection system, and the cost of processing the materials.

Some further work may be required where there are existing organic waste-collection providers that will be affected by a rates-funded collection system and/or a regulatory approach. Key questions include whether Local Government Act bylaws enable a local authority to control material in private waste-collection receptacles, and the competition regulation implications of a rates-funded system competing with the private sector.