Environment industries archive
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|A. Raptis & Sons has introduced simple conservation measures to cut their water usage by up to 50%, saving the company some $40,000 per year and achieving a significant reduction in the pollution load on the sewer. Through these simple measures, the company was able to defer investment in the more expensive - although economically viable - option of treating and recycling water. This remains a potentially profitable option for the future.
Saving water conserves one of Australia’s most precious, scarce and increasingly expensive resources. It is a major goal of cleaner production.
A. Raptis & Sons processes and distributes seafood, operating a large prawn processing factory in Hindmarsh, Adelaide. It has 180 employees and an annual turnover of $65M. The major process is defrosting, cleaning, sorting and packaging of frozen prawns. Some fish processing is also done at the site.
The company evaluated its water usage with the assistance of the University of South Australia's Food Science and Technology Centre. The evaluation brief was to find water treatment and waste minimisation strategies that were commercially viable. Raptis obtained a grant for the project from the SA Environment Protection Agency, with support from Environment Australia.
The company currently uses reticulated town water for processing, as a medium for moving products through the process, as make-up water for cooling towers and for preparation of ice. These processes generate large quantities of waste water, with contaminants including fish and prawn solids, detergents, dissolved organic matter and salts. The excisting waste-handling involved coarse filtering of the waste water, with liquid going to the sewer while solids going to waste disposal.
Water usage and costs under this system were as follows:
|Total annual consumption of water||90 000 kL|
|Cost of water consumed||$83,000 p.a.|
|Cost of solid waste disposal||$30,000 p.a.|
The breakdown of this water usage is set out in the Table below:
|Use||Period of use||Rate (kL/hr)||Rate (kL/day)|
|Process Water||6.00am - 3.00pm weekdays||30-40||~300|
|Wash down water||3.00pm - 5.00pm weekdays||~25||~50|
To investigate how savings could be made, the company’s site personnel monitored the plant’s four water meters during operations. A fifth water meter was also installed to monitor chilled water flowing from the cooling towers into the plant. (The company decided against a full audit of water and waste flows because of the wide fluctuations in usage, depending on the type and quantity of seafood being processed.)
The observed data focused attention on the critical issues affecting water consumption in the various parts of the plant. They shed light on falsely held impressions of where the most significant water-use occurred, forcing the company to re-evaluate its thinking on water consumption. The data also pointed the way to some easy and simple ways of saving water and reducing the waste load that went to the sewer.
The company cut water usage by:
The company also reduced the waste load that went to the sewer by :
The company and consultants had also evaluated a number of options for wastewater treatment to allow recycling of water. These include membrane filtration, flocculation filtration and biological treatment and filtration. However, only the biological treatment and filtration was proven to be technologically feasible. At a cost of $200,000, the treatment would have a payback of only two years, given the excisting water usage. Despite this attractive payback, the company found the simple measures even more attractive. The biological treatment and filtration option remains a potentially attractive investment for the future, especially if production increases and/or if waste disposal charges are introduced. The wastewater treatment options evaluated are included as an Appendix at the end of this document.
One of the sub-consultants used in the evaluation of wastewater treatment options, ADAS Pty Ltd, identified an opportunity for the company to improve operational efficiency by introducing ultra-violet and sand filter treatment of cooling tower recycle water. Installation of UV lamps to control microbial slime in the cooling towers may be economically justifiable through savings in biocide chemicals and the availability of excisting sand filters currently not being utilised.
A. Raptis & Sons and the environment benefited by:
A. Raptis & Sons was motivated to implement cleaner production methods because it wanted to cut costs by improving the efficiency of the operation. It has now positioned itself for the future by identifying a water-recycling method which is already feasible and will become more attractive if water costs rise, or if waste disposal charges are introduced.
The solutions employed were simple and easy and the payback was immediate. They could be undertaken by any company in this field. The only barrier to the other option - water recycling - is the significant investment involved, although it remains a positive option for the future.
A number of wastewater treatment options were investigated.
|WASTEWATER TREATMENT OPTION||TESTING||RESULT||COMMENTS|
|Membrane Filtration (Memtec Ltd)||Not trialed or analysed||Unsuitable||Chlorine content of wastewater makes membrane filtration impossible.|
|Flocculation and filtration (Q.E.D. (Aust.) Pty Ltd)||Trialed the Tangential Flow Separator (TFS)||Unsuitable||TFS treated water would, at best, only be suitable for plant wash down. While reducing COD, it retains a high concentration of dissolved solids and has a pH>8.0. High running costs and maintenance.|
|Biological treatment and filtration
(ADAS Pty Ltd)
|Trialed (with follow-up use of backwash sand filters and chlorine addition)||Suitable||Approx 80% of plant process water could be recycled.|
An economic evaluation of the biological filter option was also undertaken:
Summary of costs of the biological filter option:
|Buffer and storage tanks||20,000|
|Piping and electrical||15,000|
Based on a normal consumption of 90 000 kL/per annum, this option would have an expected payback period of two years (assuming 80% of water is recycled and saved water costed at 93c/kL).
ADAS Pty Ltd also proposed an opportunity for improving operational efficiency through introducing ultra-violet and sand filter treatment of cooling tower recycle water. Installation of UV lamps to control microbial slime in the cooling towers may be economically justifiable through savings in biocide chemicals and the availability of excisting sand filters currently not being utilised.
At 2001, as a result of a change in the seafood products being processed (i.e. introduction of oysters and increased processing of fish), single use washing of the products has had to be introduced for hygiene purposes to minimise bacterial loads. This has resulted in increased water usage compared to when the cleaner production initiatives were first implemented, although the benefits of mechanical flueing over water flueing continue to be realised.
The company continues to be conscious of water and electricity consumption and has trialed several new cleaner production initiatives, but none have been found to be highly successful. An off-peak icemaker was introduced to take advantage of off-peak energy, but this has been partially offset by the need for an ice storage room. Also lighting levels were reduced through the removal of some light bulbs but these were later replaced to reinstate brighter lighting levels.
The biological treatment and filtration option has not been implemented, primarily because it is not considered to be an investment priority.
The high variability of the seafood processing industry is considered to hamper efforts to minimise resource consumption and waste generation. During slower times, consideration is given to cleaner production options but during busy periods, the cost savings that can potentially be made are not considered to be sufficient compensation for the effort involved and loss of convenience.