Kitchen organics trial

• Introduction
• Aim of the trial
• Reasons for the trial
• How the trial worked
• The kitchen organics collected
• Summary of results

Introduction

Organic waste entering the landfill is considered a priority for management in Christchurch because of the sheer amount of organic matter and its environmental impact.

Organic waste is the largest component of the Christchurch waste stream - totalling around 76,000 tonnes per year, or 32% of the total waste going to landfill in Christchurch. Garden organics make up around 51,000 tonnes of this, with kitchen organics making up around 25,000 tonnes. Organic matter breaking down in the landfill is also largely responsible for the production of leachate and the release of methane, a powerful greenhouse gas, into the environment.

Each year the Christchurch City Council composts around 32,000 tonnes or 39% of the garden organics produced yearly. The Council is looking to increase this by a variety of means, including through the purchase of an enclosed composting facility that will allow the composting of a greater range of organic material including kitchen organics (CCC 1999). Before such an investment is made, the feasibility and social implications of collecting organic material needs to be established and this study is part of that process.

Aim of the trial

The aim of this trial was to investigate the feasibility of the kerbside collection of domestic kitchen organics in Christchurch. In particular, to investigate:

1. A collection system most suited to Christchurch
2. The community acceptance of the collection system
3. The likely costs and benefits of a city-wide service
4. Future courses of action

Reasons for the trial

Before outlining the benefits associated with collecting kitchen organics it is important to be clear about which kitchen organics the Council collected at the kerbside during the trial. Domestic kitchen organics included food related items that are produced during the storage, preparation, or consumption of food.

Examples of kitchen organics

The benefits of managing kitchen organics
The source separation, kerbside collection and composting of kitchen organics provides new opportunities to address a number of social, environmental and economic objectives.

Such efforts can:

• Recover a resource from the waste stream and produce a useful compost product
• Reduce the economic and environmental cost associated with the collection, transport, and disposal of solid waste in the landfill, by diverting significant volumes of material to composting
• Reduce the negative environmental effects associated with organic matter in the landfill, such as leachate and methane emissions
• Reduce the quantity of material entering the wastewater system and lower the nutrient loading into the environment from the wastewater treatment plant
• Provide a quality service and an alternative disposal option for material that is produced regularly by households.
• Provide an alternative disposal option for material that is seldom composted at home (e.g. meat and bones)
• Provide an alternative disposal option for people who find it difficult to compost at home (e.g. not enough space to compost)
• Minimise problems associated with composting kitchen organics at home (e.g. odour and pests)
• Reduce the incidence of black refuse bags being interfered with by animals
• Reduce the organic contamination of other recyclable materials (e.g. cans, glass, and plastic)
• Promote an environmental ethic in the Christchurch community

Council strategic imperatives
Taking kitchen organics out of the waste stream not only provides these benefits, it also fits with national policy and targets set by the Christchurch City Council. The Council is determined to reach the targets set out in the Solid and Hazardous Waste Management Plan 1998.

These demanding targets are that, taking into account the real costs, the disposal of waste per person is reduced by:

• 65% of the overall waste stream going to landfill by 2020
• 80% of the domestic waste (domestic refuse bags) collected by the Council by 2010
• 90% of green and kitchen waste going to landfill, by 2010 (The base year for these targets is 1994)

The kerbside collection of kitchen organics will greatly influence the achievement of each of these targets and consequently is a priority area for action.

Collection systems elsewhere
The kerbside collection of domestically produced organic matter has been established in a variety of communities around the world.

Germany
Waste diversion has increased in Germany from 10% to 80% in the last decade. Generally three 120 litre wheeled bins are provided to each household for the separate collection of:

1. residual refuse
2. inorganic recyclable material
3. organic material

Collection is typically fortnightly although seasonal variations are common practice. Organic collection typically includes both garden and food waste and the collection frequency increases during the summer season to cope with increased volumes and to minimise odour problems. A 10 litre bucket to transfer food waste from the kitchen to the larger wheelie bin is often provided.

Italy
In northern Italy an average of 55–80 kg of food waste per inhabitant per year was achieved through the separate twice-weekly collection of food waste in a small 10 litre container and biodegradable bag liner. 150 kg per inhabitant per year was achieved where food and garden waste were collected together in a wheelie bin. However, it was recognised that this increase did not correspond directly to a decrease in waste to landfill as organic material was being diverted from home composting.

Japan
In Japan micro-organisms have been used to reduce odours produced from food waste and assist with the collection and processing of organic waste collected from households and industry. Dr. Higa, Professor of Horticulture at University of the Ryukyus in Okinawa, discovered Effective Micro-organisms (EM) in 1980 and released the findings in his book An Earth Saving Revolution.

Collection options for Christchurch
The domestic collection system preferred internationally is three wheelie bins:

1. For the recyclable materials (paper, plastic, metals, etc)
2. For organic material including garden and kitchen organics
3. Generally a smaller container for the residual refuse

This system could be adopted in Christchurch longer-term. However, there are some limitations in the collection of organic matter that could influence its success in Christchurch.

Home composting of organic matter is the Council’s preferred option and efforts to encourage home composting will continue. Other options available to residents for the “disposal” of organic matter include taking the separated material to the refuse stations for composting by the Council or by paying for a commercial (green waste only) collection service. A Council run organic collection service will detrimentally influence these other options.

A recent survey of Christchurch households found that around 57% of people compost at home, that 40% of households use the Council’s composting facility, and around 15% have their garden organics collected commercially. Introducing a “free” (rates funded) Council collection service of organic material would greatly impact on the amount dealt with in these other ways. Such a service would maximise the organics the Council is required to process, increasing operating costs, while substantially reducing the income or material for these other existing options.

The same survey found that 60% of household dispose of their kitchen organics in either refuse bags or waste disposal units in the sink. This is reinforced by the fact that kitchen organics make up the single biggest component in the Council refuse bags. It also found that kitchen organics were less likely to be composted or collected by the commercial services. Consequently the Council is looking to introduce a small container (20 litre) that focuses on collecting kitchen organics, that would normally be disposed of in the landfill or enter the waste water system. This smaller container would not be used to collect material (garden organics) that are commonly dealt with in other ways (i.e. home composted, dropped off for Council Composting, or collected commercially).

The composition of materials in domestic refuse bags and wheelie bins

How the trial worked

Domestic kitchen organics were collected at the kerbside over an eight week period (May to July 2002) from two areas in Christchurch (Fendalton and Burnside). Collection was weekly, on the same day as the refuse and recycling collection. Involvement in the trial was voluntary and each household received all the information and materials required for the trial.

Each household received two buckets. One bucket was to place the kitchen organics directly into and could be kept in the kitchen. The other bucket was to store the kitchen organics throughout the week and was to be placed at the kerbside by residents for emptying on the collection day. Half of the households in each area received biodegradable bags to line their kerbside bucket and half of the households received EM Bokashi to help control odour.

The areas chosen
The trial was performed in two areas in Christchurch, Fendalton and Burnside. These two areas were chosen because they are distinctly different (socioeconomically), yet close in proximity. Fendalton is one of the more affluent areas of Christchurch, whereas state housing is quite common in the less affluent Burnside area, as indicated by the following pictures.

Fendalton	Burnside

The areas also fall in the Tuesday refuse and recycling collection area, which enabled the Council to prepare and respond to problems on the other days of the week. The Tuesday collection was also important because it allowed the kitchen organics to be composted and mixed in with the large volume garden organics dropped off at the refuse transfer stations over the weekend. Each area was divided in two and the households in each area were provided with either biodegradable bags or EM Bokashi.

Gathering volunteers
Two thousand letters of introduction from the Mayor and promotional flyers were mailed to selected households in the Fendalton and Burnside areas. Both asked the residents if they would like to be involved in the trial and the flyer provided a free post way to reply. From this initial mail out we received around 200 replies from households interested in taking part. A follow up letter reminding the residents to reply was sent to the households that did not respond. This letter enabled the residents to reply over the phone and took the total number of households willing to participate to 475. Taking the overall participation rate to 23%.

Materials and information provided
The Council provided all the materials and information necessary for the trial to the households. The 'starter packs' containing the materials were distributed by Onyx over the weekend (11/12 May 2002). In some cases during the trial households required additional containers because they were stolen and these were distributed as quickly as possible by Council staff.

All the households in the trial received two buckets:

1. A small kitchen bucket (4 litres) designed to be in the kitchen, either under or on top of the kitchen bench to receive the kitchen organics. This bucket had a twist top lid, intended to make it easy to open. This bucket also had a sticker clearly stating what items to place in the bucket and what items to keep out.

2. A large kerbside bucket (20 litres) to be kept in the laundry, shed or garage and to store the kitchen organics throughout the week. This bucket was placed at the kerbside by the residents each week and emptied by the Council. This bucket had a suction down sealable lid that stayed on even when knocked but came off easily, by lifting a tag on the side of the lid. This made it easy for the collectors and kept the animals or odour at bay. This bucket was labeled with the standard New Zealand food scrap label.

Households either received EM Bokashi or biodegradable bags:

	Half the households received bags of EM Bokashi to help control odour. The households were provided with instructions on how to use the EM Bokashi in the trial and were provided with additional information on what EM Bokashi is, how it works and what to do if there were any problems.
	The other half of the households received biodegradable bags. These bags were made of cornstarch and were completely biodegradable. Toward the end of the trial the Council was kindly given an alternative degradable bag (plastic composite) to test. Instructions about the storage and use of the bags was also provided.

All the information provided contained contact details (telephone, e-mail) and referred people to the website for additional information or help.

Field measurements
Council staff took measurements at the kerbside each week during the trial (come rain, hail and snow - literally!). The measurements taken were to gauge the household participation, hygiene, the suitability of containers (bucket and bag), the effectiveness of EM Bokashi, and the level of contamination. A summary of the measurements taken in is provided below.

The measurements taken in the field:

• Street name
• House number
• Bucket Weight
• Bucket Volume
• Was the bucket tipped over (yes/no)
• Insects present (yes/no)
• Offensive smell (on a scale of 1-5)
• Amount of liquid (on a scale of 1-4)
• Type of contamination (paper, plastic, metal, glass, twisty ties)
• State of biodegradable bag (intact, minor defects, major defects, totally rotten)
• Use of EM Bokashi (no EM, not enough EM, too much EM, not mixed in)
• State of bucket (washed or not washed/dirty)
• The total weight of kitchen organics collected by Onyx
• The weather at the time of collection

Collection
The kitchen organics were collected by Onyx in a sealed (water tight) refuse collection truck. The buckets were tipped into the back of the trucks and banged to knock out any loose organic material. The buckets were then placed back onto the person's property (as much as possible) to avoid buckets being stolen or knocked around on the street due to wind or animals.

Telephone survey
A telephone survey was performed immediately after the collection trial finished. The calls were made by the Council, to participants during the evenings and in the weekends. Each household was rung back until an answer was received. A total of 316 households completed the survey.

The kitchen organics collected

Overall the Council collected 12 tonnes of kitchen organics from around 300 homes. The total number of buckets emptied over the 8 week period was 2490 buckets. Some households set out buckets every second week (8%) while most placed them out every week (87%). Roughly 20 households received buckets and decided not to start the trial. Another 14 households joined the trial during the first few weeks of collection. The participation was highest in the first week, and then declined only slightly over the 8 weeks.

In the first week, the amount collected was high because people had stockpiled their kitchen organics in the preceding week, in anticipation of the collection service commencing. The amount collected and the participation in week 6 was also high because residents were catching up after a snowstorm that occurred on the collection day in week 5. (Note that all other collection days occurred in fine frosty weather, typical of winter in Christchurch and would not have adversely affected the results). Residents were given a reminder that the trial was about to end during the last week and this would have boosted the figures for the last collection. So, excluding extraneous impacts (as just mentioned) the participation fell by 20% over 6 weeks (between weeks 2 and 7) for both areas.

There was no difference in participation rates between the two areas indicating that a similar proportion in both socioeconomic areas would be willing to separate kitchen organics for collection.

Summary of results

Conclusions
The kerbside collection of kitchen organics was a resounding success. Those involved were overwhelmingly supportive of the service and were not only willing to continue to use it in its current form but were also willing to pay for the service in the rates.

Nearly all the household involved used the service on a regular basis, and most noticed a reduction in the waste that they produced. The organic material collected was generally odourless, was relatively dry and free of contaminants. The biodegradable bags used kept the kitchen organics well contained and kept the buckets clean throughout the trial. EM Bokashi minimised odours and the materials collected composted well in an open air windrow system.

The cost of a similar service city-wide in Christchurch was estimated at around $1.5 million or $140 per tonne. Such costs place this service in the order of the kerbside recycling service ($160 per tonne, excluding processing costs) and the domestic refuse collection service ($95 per tonne, including disposal). However, the costs also need to be weighed up against the economic and environmental benefits that such a service will provide.

The benefits of diverting this material chiefly relate to the avoided landfill costs ($84 per tonne), the reduction in costs associated with treating leachate and landfill gas, and the beneficial use of the material as a compost product. Taking these 'savings' into account, along with the relative ease of the collection operation and the overwhelming public support from those involved, gives confidence in the viability of such a service in Christchurch.

Recommendations
The following recommendations are based on the findings of the research:

• An enclosed processing facility for putrescibles material should be established in Christchurch so the material collected from a future kitchen organics collection service can be adequately processed.

• A kitchen organics collection trial should be performed during Summer to assess the impact of higher temperatures on the collection system and the impact of season on the amount of material collected and on the participation. This trial should continue for a longer time to allow those involved to establish a routine and to become totally familiar with the service. Lining the buckets (with biodegradable bags, paper or plastic bags) would be crucial for the collection service to be acceptable to the public. A future trial could test a range of lining options.

• The container design needs further consideration:
  a) the kitchen container should have a detachable flip-top lid to make it easier to place food scraps into it
  b) The kerbside container needs to be wide and squat, it should have an attached flip-top lid and the container needs to be a distinctive colour to stand out from the other kerbside collection containers.

• Consideration should be given to providing a similar collection service to businesses - for example, small cafes or outlets where kitchen organics are typically disposed of to landfill. This should also be done in consultation with pig farmers who provide another avenue for this material.

• Home composting should be promoted further to encourage people to take greater responsibility for the waste that they produce.

• Support should be provided to commercial green waste collection services to maximise their uptake, as apposed to mixed refuse wheelie bin collection services.

• Supermarkets and retail outlets should be encouraged to move towards degradable carry bags issued at the point of sale, as these can easily feed into a putrescible collection system.

Overall, the collection system used was a success, with good participation and was highly regarded by those involved. The City Council should instigate a kitchen organics collection system in Christchurch as soon as processing technologies allow.