Plant & Works Engineering
Ensuring water flows sustainably
Published:  08 April, 2015

Efficient water and wastewater treatment is essential from both a legislative and operational perspective. Nick Simpson, sales and marketing director from SUEZ environnement Industrial Water UK looks at the technologies and solutions available to ensure your water flows more sustainably.

For many busy manufacturers, water and wastewater treatment processes can sometimes be seen as a distraction from core activities. However, failure to comply with legislation or meet targets related to wastewater disposal and treatment can have a detrimental effect on the stability and profitability of a business. Reduced manufacturing productivity and potential punishment in the form of fines by industry regulators are just two examples of costly, yet avoidable consequences. Therefore, in order for businesses to protect themselves, effective water and wastewater treatment must be implemented.

Completing the groundwork

There is a cost to industrial effluent treatment and if poorly managed, operational issues may occur. Carrying out site-wide feasibility studies or audits before modification or building a new water or effluent treatment plant is crucial, particularly when monetary investment is required or legislation needs to be met. This identifies the right treatment and technology for your process, which meets both current and future drivers, such as an increase in production or expected change to discharge consent. A study also recognises possible areas of weakness, and ensures operations and maintenance facilities are developed in accordance with best practices.

Older sites will often have unknown and potentially complex factors to consider below ground. To ensure these subterranean issues are addressed ahead of work, and to guarantee every element of installation is as cost-effective and efficient as possible, it’s expedient to partner with an experienced water management company who can use their site and sector knowledge to evaluate the best course of action. By offering an integrated solution, a credible water and energy balance can be reached, with opportunities for saving money and methods for optimising performance.

Once the audits and surveys are complete, the plant operator, together with the water management company, can assess the size of the water system needed to meet process requirements and ensure all materials and fittings both maximise lifespan and minimise maintenance. This is also an excellent opportunity to see if a water stream can be re-used elsewhere on the plant.

Reducing Risk

Inevitably incidents can occur, but any risk can be reduced with good communication between all operational staff. For example, if the production team are able to pre-warn the effluent treatment plant team that an unexpected waste stream is heading their way, appropriate fail-safe action can be taken to avoid a major incident such as a discharge breach.

Modern water treatment technologies

There are of course an array of innovative water technologies on offer when installing or upgrading a water treatment plant; with considerations of running costs, energy efficiency and sustainability being part of the final selection process. By collaborating with a trusted water management company and understanding the processes on offer, the best treatment to suit the application can be agreed.

Many production facilities are looking at ways to become more sustainable and one method is by recycling or re-using wastewater. This involves some level of treatment and there is a range of tried and tested systems available in the market place that can achieve this. One method is a Membrane Bioreactor (MBR) which recovers water for reuse in non-production applications such as cleaning or combined with Reverse Osmosis for direct reuse. More reliable than more traditional treatments and providing better water quality, it meets stringent effluent discharge standards while addressing challenges such as variable influent flows, space and time constraints.

A biological treatment process uses a mixed culture system; ideal when refurbishing existing water treatment plants. This can be used as a preliminary biological treatment process or as a global treatment line specifically for removing carbonated contaminates from industrial effluent by treating BOD (Biochemical Oxygen Demand) and COD (Chemical Oxygen Demand). A space-saving, simple and flexible biological treatment system can provide reliable facilities, even when faced with large variations in influent quality. It also offers flexibility in terms of variable influent quality while helping to minimise operating costs; ideal if looking to extend existing capacities.

A high-performance aerobic biological reactor uses bacteria attached to a specific, submerged fixed-bed single-layer material with an upward water flow and airflow. It can be used as a turnkey solution or finishing treatment process, providing one of the best technical solutions for treating industrial effluent. It can cope with high flows and high load variations, even working within strict size constraints.

Aerobic treatment is an effective solution for the biological treatment of diluted effluent from refineries and petrochemical sites and other types of water produced by the oil industry, as well as for the biological treatment of high-flow diluted effluent from the pulp and paper industry, with an improved reduction of COD (Chemical Oxygen Demand) and suspended solids. It can also offer a combined treatment of both carbon and nitrogen, while also tolerating toxic compounds.

An anaerobic biological treatment works by breaking down organic carbon, generating methane that can be recovered and cleaned to produce energy. Typically, removing 1 ton of COD (Chemical Oxygen Demand) has the potential to produce around 3 500 KWh.

There are a range of anaerobic biological digesters to choose from, each producing recoverable by-products with a small footprint. A Contact Reactor, for instance, is suited to chemical, pulp and paper residue, and the treatment of complex food juices. A Fluidised Bed is used to treat evaporation condensate and alcohols, while Granular Sludge (UASB) is a process generally utilised in treating effluent from sugar refineries, wine producers and breweries. There’s also an integrated end-to-end solution, incorporating the reuse and recycling of treated water, as used in particular by the biofuel industry.

Mobile water treatment units

Hiring a mobile water treatment unit on a long term basis enables the business to produce high quality water quickly with no high capital investment. In addition to their value as a temporary solution during planned maintenance shutdown periods, mobile water treatment units are a highly efficient and cost-effective option for sites that experience variation in process water requirements throughout the year in terms of quality and quantity.

Mobile units can also meet seasonal increases in demand, or fluctuations to where raw water is generated. This can also overcome delays in the delivery of a demineralisation chain, as well as the need to access large quantities of high quality water for steam-blowing, which can be addressed while avoiding costly capital investment in permanent facilities.

The energy factor

Energy consumption is a big issue for water treatment plants, and adapting water quality and quantity to suit your specific site needs can generate considerable savings within your water cycle as well as reducing energy output.

For example, the most energy-intensive component of an effluent treatment plant is aeration, accounting for 40 to 70% of the energy used. However, new solutions such as continuously adjusting the airflow delivered to the biological sludge treatment stage are helping to reduce this amount.

The solution and specialist best suited to your water needs

To ensure the best possible water and wastewater infrastructure at a plant, selecting an appropriate specialist contractor is essential. They should be able to provide the services of a full engineering design team with a depth of experience to resolve specification issues quickly and reliably. This will ensure the correct specification for materials and fittings to maximise lifespan and minimise maintenance, keeping vital water systems online and preventing costly downtime.

A supplier with a breadth of expertise can deliver exceptional technical and practical knowledge. And this level of experience means the right solution can be identified from the outset. Such a supplier will help their plant partners to fully understand issues that drive the industrial water cycle, including cost, sustainability, politics and legislation. Businesses are then able to evaluate the options available, such as system efficiencies, water reuse and water audits, and take steps towards enhanced efficiency.

The case for a mobile solution

When the differences in demineralised water between high and low seasons were identified, one plant decided to implement a fully automated mobile demineralised water treatment unit using microfiltration and FlexosmO reverse osmosis technology. In addition, a complete follow-up maintenance service was carried out; all of which guaranteed a continuous demineralised water flow and uninterrupted water production.

The outcome was reduced operational costs of 30% during its low production period. In addition, because of the limited quantity of chemicals used by the mobile unit, the customer reduced their environmental impact.

Ten key pointers when specifying a water treatment plant

1. Carry out a site-wide survey to establish the amount, where and how of current water use.

2. Engage with an experienced supplier who can identify savings, unknown losses as well as ring-fencing re-useable water streams.

3. Adapt the water quality and quantity to suit your plant - this can generate savings within your water cycle, especially around better use of energy.

4. Be aware of current over-specification, identify how capacity or complexity can be reduced, while accounting for future changes in demand.

5. Introduce innovative water recycling technologies that allow process water to be reclaimed and wastewater to be reused safely and sustainable.

6. Take on board the specialised solutions can cut energy consumption.

7. Consider anaerobic digestion; it produces energy from effluent: typically, removing 1 ton of COD has the potential to produce around 3500 KWh.

8. Any risk of incidents can be reduced with good communication between all operational staff.

9. Allow the experts to care of the wastewater system, so you can take care of business.

10. Consider leasing a mobile industrial water treatment unit, so treatment carries on while the permanent water and wastewater treatment plant is being constructed.

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