Archived publication
This publication is no longer current or has been superseded.
Executive summary
Introduction
The purpose of this report is to investigate the long-term scale, viability and risks of developing a post collection waste reprocessing sector for used tyres, plastic and glass in the Wellington region.
Waste Stream Quantities
The existing and predicted quantity of recovered material for each individual waste stream is as follows:
Table: Quantities of glass, plastic and tyres landfilled and diverted in selected cities in Wellington region (tonnes)
| City | Glass Landfilled | Glass Diverted | Total Glass | Plastic Landfilled | Plastic Diverted | Total Plastic | Tyres |
|---|---|---|---|---|---|---|---|
| Wellington |
5,921 |
3,300 |
9,221 |
10,636 |
720 |
11,356 |
1,516 |
| Lower Hutt |
2,274 |
1,271 |
3,545 |
9,726 |
275 |
10,001 |
876 |
| Upper Hutt |
* |
999 |
999 |
* |
216 |
216 |
318 |
| Porirua |
1,246 |
1,058 |
2,304 |
4,986 |
229 |
5,215 |
424 |
| Total |
9,441 |
6,628 |
16,069 |
25,348 |
1,440 |
26,788 |
3,134 |
* Upper Hutt's waste stream is included in Lower Hutt landfill figures
Future changes in waste stream quantities were investigated along with the effect of waste minimisation programmes or initiatives. Changes in the total waste stream quantity are unlikely to be particularly affected by population dynamics or by changes in economic conditions, however, as more resources are directed towards specific waste streams increased diversion rates and improved economies of scale may be achieved.
Reprocessing Technologies For Tyres
The main reprocessing options for used tyres in New Zealand include:
- Energy Recovery
Waste tyres are a high grade energy source that may be used as an alternative fuel in cement kilns, however national collection and transportation infrastructure would be needed to secure a consistent quantity of feedstock. Used tyres may also be burned in a range of developed and developing technologies that include pyrolysis, gasification and polymerisation, with the end products including energy, carbon black and steel.
- Paving Applications
Crumb rubber may be used to produce rubberised asphalt concrete. It provides a variety of benefits that include a longer lasting surface, resistance to rutting and cracking, reduced road noise and reduced costs, and potentially it is a significant and viable end use for used tyres.
- Civil Engineering Applications
The use of shredded tyres to replace virgin aggregate in civil engineering applications is a significant potential end use market.
Reprocessing Technologies For Plastic
The main reprocessing options for plastics in New Zealand include:
- Mechanical Processing
Mixed or sorted polymers are cleaned and transformed into flakes or pellets and used in injection moulding or extrusion processes to manufacture products such as pipes, pots, buckets and mats. Mechanical processing is currently used across New Zealand and an opportunity exists to expand the current reprocessing capacity in the Wellington region.
- Chemical Reprocessing
Chemical reprocessing involves converting long chain plastic polymers into virgin resin, or breaking polymers into their constituent molecules for reuse in refineries or petro-chemical production. This may be achieved through technologies such as pyrolysis, glycolysis and methanolysis However, such technologies often require significant capital investment and are in various stages of development.
Reprocessing Technologies For Glass
The main reprocessing options for glass in New Zealand include:
- Container Manufacturing
Currently all crushed glass generated in the Wellington region is transported to Auckland for reuse in the container glass manufacturing process.
- Aggregate
Crushed recycled glass may be used in aggregate applications such as pipe bedding, drainage backfill and as a sub-base for flexible and rigid pavement. In addition it may also be used as a concrete aggregate or as decorative aggregates in landscaping.
- Filtration Media
Crushed glass of a suitable particle size distribution and quality can be utilised as a granular media for filtration applications such as potable and wastewater treatment and in swimming pools.
Template for Assessing the Regional Suitability of Waste Reprocessing Technologies for Tyres, Plastic and Glass
A template has been designed to summarise and assess the options available for the reprocessing of tyres, plastic and glass for any given region in New Zealand. The template has been used to assess the development of a reprocessing sector for each waste stream in the Wellington region and is included overleaf. The shaded area depicts information on various technologies and applies everywhere in New Zealand, while the non-shaded area (Barriers to Regional Suitability), varies across New Zealand and has to be determined for each study region. This template takes into account factors such as distance to reprocessors, existing regional reprocessing infrastructure, transport costs and volume. In order to increase the reprocessing capacity of the Wellington region the template identifies a number of complex but fundamental barriers that need to be addressed if advances are to be made.
