Turning wastewater into an economic resource

by Editor
0 comment

Economic optimisation of wastewater treatment is vital for Australian manufacturing and processing facilities aiming to curtail costs, writes Steve Edwards of pitt&sherry.

Today, cost management has become a leading indicator in ensuring a viable future, creating a tenser situation within what was already a difficult environment for manufacturers. In an effort to contain costs, a growing area in manufacturing facilities focuses on the economic optimisation of wastewater treatment.

Economic optimisation of wastewater treatment is vitally important for Australian manufacturing and processing facilities aiming to curtail costs. What we traditionally regard as wastewater can be a misleading concept, as wastewater is in fact a resource that must be accounted for in terms of its energy output, if nothing else, so sometimes there is an upside.

Manufacturers need to identify where they can reduce wastewater discharge and how the remaining resource may then be reused in an economic and sustainable manner. More often than not, the best economic outcomes can also be the best for the environment.

Capital spend

The big question for manufacturers is how to find the right balance on capital spent creating wastewater treatment assets before funds are paid to the local water authority for treatment.

pitt&sherry has worked with companies in the dairy and mining industries by analysing the economic case for different wastewater treatment methods. For one dairy facility development, pitt&sherry looked at the contractual requirements to provide a perspective between sending wastewater to the local authority and the required spend to treat the water to a higher condition on-site.

It was found the dairy manufacturer had several technology options. An approach that stood out was to move the waste through up to three stages of treatment for it to reach the required condition of the water authority. In this case, the treat-on-site option was a better economic outcome.

As part of this process, the manufacturer also needed to decide how to spread its capital between these three stages.

The key economic questions were: does the company heavily focus on spending its budget on stage one? Or is it more economical to spread the capital evenly over three stages? It can be difficult for clients to assess these questions, however, as there is a lot of information that needs to be processed.

First, there are manufacturing claims that are often based on industry averages and norms for a treatment type. The company must know whether the claims being made are realistic. It also needs to understand the implications of the possible scenarios for its wastewater management, which is unique for each facility.

It will also bring up issues with peak flows and average flows of wastewater, which can add costs to the client because of charges on a number of different areas.

For this case, elements like peak flows and concentration of wastewater were analysed and included in recommendations to the client. Though the claims still have to be sorted through to ascertain what works and what impact each option has on life cycle cost.

For the dairy company, analysis was provided showing a 15-year net present cost difference of up to $4 million between options.

Risk analysis

On another dairy project, pitt&sherry’s focus was more on the risks involved with the economic decisions the manufacturer had already applied to its wastewater treatment. The manufacturer was taken through a comprehensive hazard and operability study (HAZOP), including considering various risk scenarios by analysing what would happen if the Environment Protection Authority (EPA) raised these situations, as well as the potential costs involved in these instances.

A system capable of holding the water leaving the plant was designed, taking into account that the facility has a 24-hour cycle, which produces small amounts of wastewater during the day then peaks at night.

Depending on the costs involved, a facility might look at the risks and say, ‘If a tank bursts we’ve contained the spill on the other side from the water authority and from an environmental perspective.’ This still raises questions from the water authority regarding what would be done with the contained waste after the spill. The client did not want these risks or the excess costs of building and maintaining complex holding and disposal systems.

To accommodate this, a system was designed with surges and flows that allowed for the wastewater to be contained in the factory for a short while when spilled, but then released once it reached the parameters of the wastewater authority.

The design allowed for additional tanks, which may not be used, but have been installed to take all of the extra water and have it properly treated by sensing the pH and pumping the water slowly back into the existing outlet mostly without additional chemical treatment cost.

Manufacturers can optimise their economic choices when treating and recycling wastewater by investigating a variety of options.

A wastewater treatment plant may form part of a greenfields project, it can be an element of a facility upgrade to improve efficiencies or it can become a part of meeting the rigorous standards water authorities have applied to the area in recent years.

The principles don’t change despite the change of industry. They are still the principles of sustainability: reduce use and recycle where possible. If these principles are applied to each unique situation, the economic gain will follow. It’s just a matter of receiving payback in reduced disposal charges, compared to the cost of the equipment and the process.

Dr Steve Edwards is principal consultant of pitt&sherry.

This website uses cookies to improve your experience. We'll assume you're ok with this, but you can opt-out if you wish. Accept Read More