Solid waste management is challenging and complicated due to the increasing categories of materials coming in the waste stream. Conventional method adopted in developed countries so far is land filling which has lesser requirement of understanding the composition. Currently a better strategy for solid waste management with maximum resource recovery and recycling is being adopted by most of the countries. For this, up-to-date and comprehensive waste composition and generation data is necessary. Although those data can be used for a primary assessment, the waste stream is directly linked to the culture, disposal and collection facilities, economic background and climatic conditions. Case-by-case audit is therefore essential for a strategic output oriented assessment.
What is waste audit?
Waste audit is a systematic and quantitative approach to determine the composition of a waste stream from a particular location or activity. Waste audit may be conducted at any levels such as household, individual business, industrial/commercial to a municipal/ council level. Audit should ideally be conducted to incorporate seasonal and daily variations and repeated after every major change in the business or activity or after every intervention. This can provide quantitative and qualitative data on the individual components and audits results can be analysed for multiple outcomes.
Audit is needed for
• General SWM planning including the design of waste facilities (e.g. landfills & collection systems)
• Designing a waste collection program
• Developing sorting system for better recovery of specific components
• Exploring the potential to recover a particular resource
• Assessing the suitable technology for handling individual waste stream
• Legislative and administrative intervention
• Revising waste management strategy, technology or strategic changes for overall efficiency and
• Business development and feasibility studies around waste management
Waste audit reports also throw light on the general lifestyle and activities in the community. This helps develop job opportunities and other infrastructure for the community.
Conducting a waste audit
Questionnaire or data collection sheet needs to be set up based on the specific reasons for conducting the audit and what information in particular is sought by that audit. However, it is ideal to monitor and audit the waste stream in detail to make use of the effort to the maximum. The waste audit team should include officials from the administrative department, the auditor who understands the technical aspect of data collection, the organisers that facilitate sample collection, and the group that sorts the waste according to the categories in quantitative or qualitative manner. Organising sample collection will require some intervention in the routine waste collection process. A prior understanding of the waste collection day, frequency of collection, waste disposal methods used and of the general community and activities will be necessary to facilitate sample collection. Audits on peak and off peak waste generation days will be useful for technology implementation and better precision in the process.
The audit process should maintain good hygiene and work safety procedures as it involves manual handling of a waste stream that could contain hazardous materials of physical, biological and chemical nature.
The audit team should be supplied with and be ensured that they use disposable facemasks, coveralls, rubber gloves (cover up to the elbow) waste picking tools such as tongs/scoops, required number of bins/bags and closed footwear.
Municipal waste is more complicated due to the diverse kind of materials that come in the waste stream while commercial waste stream has lesser components but in larger quantities. Planning meetings to discuss the need, process and expected outcome of the waste audit should be conducted and well established before the audit is conducted. These meetings should be used to collect baseline information on the structure of the audit region and waste handling practice. Preparation meetings for waste audit should ensure that the process takes the right sample for assessment.
In the sample collection method, sample quantities and sampling location should be representative of the whole system under study. A practice or demo audit before the actual audit is ideal for a group that is new to conducting audits to prevent confusion on the day that could affect data collection.
Audit for technology selection
Resource recycling strategy implementation requires a thorough understanding of the composition, quality and quantity of the materials that can be recovered from a waste stream. This data forms the baseline to assess the feasibility of resource recovery of a particular component in a waste stream. For the application of technology, in a feasible manner, a minimum quantity of raw material in the required quality will have to be recovered from the waste stream. Therefore, technology selection and application should be based on the information gathered through a waste audit. Depending on the availability of raw materials, business opportunities can be assessed for different waste streams whether it is for organic or for non-degradable materials such as plastics, aluminium, metals etc.
Waste audits could provide innovative ideas on technology and business opportunities. Therefore, audits should be planned to get as much detailed data as possible and the values entered in an excel sheet. This will provide options of combining and splitting various data as required for further applications.
The following case studies were conducted with a specific purpose of developing a treatment and recycling strategy either onsite or off site. The solid waste generation directly reflects the activities around the place. They were conducted at different locations but within the same overall political and regulatory arrangements of Australia. The case studies reflect a general municipal waste generation from Councils in the mainland, an Island under the administration of Australia, a remote mining village and a lifestyle village in the suburb. The purpose of all those audits were specifically different, but with a general interest for exploring options for onsite treatment, recycling and waste reduction strategy.
Percentage of different components from various audits in Western Australia
|Material||Bridgewater lifestyle village (Nair&Anda, 2007)||City of Stirling 1999 (WMB, 2003)||City of Canning
|Mining Village Canteen/food serving. (Nair et al., 2008)|
Christmas Island is located 2600km North West of Perth in the Indian Ocean with a population of less than 5000 of which, only one sixth is local and the rest transient population. This implies on the high accommodation and food catering needs, all of which sourced from outside the Island. Similarly having a detention Centre on the Island that can accommodate about 3000 people at one time, food waste and packaging waste were higher than a normal Shire waste. This was reflected in the waste audit conducted at the landfill site on the Island. As there were no resource recovery strategies before the waste got to landfill, the percentage of mixed waste contaminated with food waste was also high. As some diversion of cardboard had occurred, the total quantity could slightly vary.
Results of waste audit conducted at the Christmas Island landfill site (Nair, 2011)
|Components||Percentage by weight|
|Contaminated food waste||18.72|
Lifestyle Village, Council and Minesite village audits
A lifestyle village (Bridgewater Lifestyle Village) for retired and semi retired people in Perth, Western Australia was audited for strategic planning and system development for onsite sorting of waste, first level recycling and treatment of organic waste . On comparing with the general municipal waste, audit results conducted by Murdoch University in 1999 for the City of Stirling (WMB, 2003), the, lifestyle of such a village was clearly demonstrated with higher percentage of newspaper and magazines, glass bottles (more time to relax) and lesser food waste.
Minesite village has a different social set up with only adults, no family or children and comprised 100% shift workers. The audit results may not be truly comparable as the conditions under which the audits were conducted were different concentrating mostly on kitchen and cabin waste. The data provided in the table above, is percentage composition that mostly reflects the activity and lifestyle and does not provide a data for onsite treatment or recycling opportunities. The data should be presented in quantitative form to work out the technology feasibility assessment. The reports have presented the data quantitatively.
A systematic purpose oriented waste audit can provide vast amount of data for administrative, technical and commercial strategies in waste management. The quantitative audit will provide information on capacity development while qualitative assessment mostly reflects the activities the community/business is engaged in as well as the social and cultural lifestyle of the society.
RAUM International Pty Ltd, Australia
Adjunct Faculty, Murdoch University, Western Australia
Paper presented at the International Conference on Waste,
Wealth and Health organised by IIWM