The Caltex Refinery in Lytton, Brisbane has implemented substantial changes in its solid waste management system since commissioning of the refinery in 1965. A number of new initiatives have been introduced within the solid waste management program and the integrated environmental management system. These initiatives were based on the cleaner production elements and in particular "at source" wastes reduction and recycling of waste products. This program resulted in a considerable reduction of waste generation and substantial savings in waste handling and disposal costs.

Construction and commissioning of Ampol Refinery ( now Caltex Refinery ) was completed in 1965. It is an integrated refinery with two crude processing units, fluid catalytic cracking, HF alkylation, polymerisation and catalytic reforming. The refinery has an advanced waste water treatment system which includes segregated oily, contaminated water and storm water systems, and secondary biological treatment plant.

Solid waste management in the refinery’s early days was comparable with the petroleum industry standards at the time. However, these standards and the refinery waste management practices along with them, have undergone substantial changes over the last three decades. These changes occurred due to a variety of reasons namely company policies, economic conditions, regulatory and licensing requirements, health, safety and changing public attitudes. This case study aims to present a detailed description of improvements in the refinery’s solid waste management over the last decade and some of the results achieved.

A number of solid wastes from various sources are generated in the refinery manufacturing process. The majority of these wastes are of a hazardous nature due to contamination with hydrocarbons and other contaminants. These wastes have been categorised and tested and, for most of them, Material Safety Data Sheets have been developed. Table 1 characterises major wastes generated at the present time.

Table 1. Solid Waste Inventory

Source	Material Characteristic
FCC unit	Catalyst fines Al2O3, SiO2
Alky unit	Lime sludge CaF2, Ca(OH)2
Storage tanks	Oil contaminated solids
Oily water sewer	Oily sludge
Various sources	Contaminated soil
Process units	Drums Oil/chemicals

There is also a variety of uncontaminated, recyclable solid wastes which have a considerable impact on overall management and costs. Table 2 summarises these wastes.

Table 2: Inventory of Uncontaminated Recyclable General Wastes.

Material	Generation t/year
Clean drums	20
Scrap metal	450
Waste paper	6
Cardboard	10
Aluminium cans	2
Green waste	1

Earlier Upgrades

Before the late 80’s solid waste management involved "end of pipe" solutions ie. primary treatment, stockpiling on site and off site disposal to local authority disposal site.

With changes of economic conditions, higher environment and industry standards, these practices no longer met the company environmental requirements, and had also become very expensive. A number of initiatives were undertaken to improve the waste management in the early 90’s. These initiatives included some elements of emerging cleaner production techniques, putting the refinery ahead of other refineries in Australia:

• the refinery commissioned an external study to determine the suitability of FCC catalyst for recycling in the cement industry. The study resulted in positive recommendations for recycling and this was followed-up by a successful recycling program. This program continued for almost 3 years reducing waste disposed and the refinery manufacturing costs until the local cement plant started closing down. The off-site landfill disposal of catalyst was reduced by 85%, as some of the catalyst still had to be disposed of that way.
• A new storage tank cleaning procedure was introduced. This procedure reduced considerably the generation of oily sludge as well as its level of contamination. The process is based on use of "cutting stock " ( usually diesel or clarified oil ), circulation of mixture to maximise dissolving hydrocarbons and finally separation of solids and water. The oily phase is directed to crude units for processing. Waste water separated in the process requires treatment; it is therefore drained to the waste water treatment facilities for final treatment and disposal. Hydrocarbon contaminated solids are collected in a storage container and transported for disposal at the local authority disposal site. Using this procedure up to 80 % reduction in quantity of disposable material was achieved along with significant reduction in its contamination.
• An on-site landfill for clean waste was closed down improving general site conditions.
• Some on-site locations were cleaned-up. Accumulated solid waste and contaminated soil from these sites was removed and disposed of at the local authority disposal site.

Progressive Improvements

In recent years the rate of change has accelerated, pushed by the company’s changing policies and a drive to implement best practice standards. This was ahead of changes in the regulatory requirements, anticipated closure of the local authority disposal site and rapidly increasing costs of waste disposal.

The new situation required a more systematic approach. A site environmental audit was conducted by an external contractor and resulted in a number of recommendations for improvement. These improvements included review of solid wastes management and development of a waste management program. Both these programs became a part of a wider environment upgrade program under the site’s integrated environmental management system developed in 1994.

The basis for the waste management program was the introduction of cleaner production elements to the manufacturing process. These elements included:

• Inventory of solid waste streams and testing of waste quality.
• Identification of waste reduction and opportunities for minimisation.
• Market research to find waste recycling technologies in other industries capable of absorbing refinery wastes.
• Development of suitable and acceptable on-site treatment options. This includes construction of hydrocarbon contaminated soil bioremediation facility.
• Economical evaluation of all alternatives
• Evaluation of all new projects for waste generation and possibility of minimising through Cleaner Production techniques.
• Development of solid waste handling procedures.
• Awareness training of refinery personnel.

Development and implementation of the waste management program resulted in a number of process related projects aiming to reduce/minimise waste generation. These projects are being implemented now and it has become clear that considerable reduction in waste generation is being achieved. A full assessment of the reduction is to be done when more data becomes available. The projects listed below are the examples of process related improvements.

Projects

• Feed dryers and catalyst rerun column were installed in the Alkylation Plant. This equipment allowed reduction of spent caustic generation and subsequent reduction in lime usage and spent lime generation. On average, 30% reduction of spent lime was achieved.
• Study of the site soil erosion was commissioned to determine measures to control the erosion and prioritise required work. The erosion has been contributing to accumulation of silt in the wastewater storage ponds and subsequently adversely affecting operation of the waste water treatment facility. This material needed to be excavated on a regular basis from the ponds and therefore contributed to excessive cost of waste water treatment and accumulation of contaminated solid waste. The study recommended a number of measures to control erosion with priority on a hill located on a boundary of the site. This site was reprofiled to reduce slope, vegetated, and the excess of excavated soil has been used as an earth fill in another environmental project (Green Barrier zone ). The effect of the hill erosion work on quality of stormwater has yet to be finally assessed however it is believed that at least 40% reduction in silt generation will be achieved. Implementation of other recommended erosion control work will continue this year.
• Crude storage tank waterdraw facilities were upgraded to Best Practice standard. This project resulted in installation of an enclosed tank waterdraw system which allows collection of waste water in collection tank and subsequent final treatment in the waste water treatment facilities. Water drawing into bunds practised earlier has ceased, reducing contamination of soil in bunds.
• Replacement of 205 litre chemical drums used in the process area with bulk storage tanks. The use of these tanks reduces the number of drums for disposal and contamination of wastes with chemicals.
• Tank maintenance procedures were developed for cleaning of all refinery storage tanks. These procedures are based on best practice standards and ensure application of sludge minimisation, hydrocarbon recovery, processing and treatment of waste water.

Recycling initiatives

These initiatives resulted from an intensive research of external industrial technologies capable of reuse of the solid material. This research was conducted by refinery personnel and external contractors resulting in a number of identified alternatives. Most of the recommended options have been implemented:

• An earlier study to determine the suitability of the FCC catalyst in the cement industry recommended use of this material in the cement manufacturing process. The catalyst was successfully recycled in 1995-1997. Due to the shut-down of the local plant, other alternatives are being explored, some of which are promising a successful outcome.
• A number of recycling options have been identified for alky spent lime. These options include recycling in the cement industry and use as soil conditioner in the agricultural industry. At present, the option of utilising the material in the manufacturing of soil substitute is the best and most economically viable. This option was actively implemented in 1997 resulting in the utilising/recycling of 3000 tonnes of material.
• Drum recycling was intensified during the last three years. Initially only clean drums were sold for recycling, however later, the contractor installed cleaning facilities and obtained an environmental licence, contaminated drums have been included in the recycling program.
• A general refuse audit conducted in 1995 identified that a substantial reduction could be achieved by the implementation of waste segregation and recycling programs. These programs involved aluminium cans, waste paper, cardboard and glass recycling. Financial benefits included revenue from sale of recyclable wastes and reduction in costs of handling and disposal of general refuse. Recycling of other wastes such as scrap metal and waste electric cables have been in place for a long time. An estimated revenue of $20,000 per year was generated as a result of total recycling of general wastes.

Advantages of the Process

The average annual rates of reduction in solids wastes over the last decade are shown below.

Waste	Reduction %
FCC catalyst usage disposal	20 80
Alky spent lime generation stockpile	30 25
Tank sludge generation disposal	up to 80 up to 80
Disposal of other sludges	80
Drums	40
General refuse	40

These results show considerable reduction in generation and disposal of solid wastes.