Case Studies Editorial

Contact: Kevin Prior Date: August 4, 2008

This is where we will put our Case Studies. You can see for yourself what we have been up to and what we have achieved. We also aim to tell you how much can be saved taking in both the environmental and economic terms when implementing improvement projects


Impacts of Water Savings

Contact: Kevin Prior Date: October 27, 2008

A number of organisations who were undertaking water efficiency programmes wanted to know if they were creating problems elsewhere in the wastewater system. We worked with the Pennine Water Group at Sheffield University to examine the potential problems and devise ways of avoiding them.

Taking an integrated view of water in the production plant can however highlight cost savings both in terms of supply and terms of disposal.

What was the problem?

The Department of Environment, Food and Rural Affairs (DEFRA), Future Water Strategy aims in England and Wales to:

  • Reduce domestic water usage to 120 litres per person per day by 2030.
  • Introduce new proposals to tackle surface water drainage.
  • Introduce new proposals to reduce water pollution by tackling contaminants at source.

Action to deal with point sources of pollution (e.g. from industrial processes and sewage treatment works) and use River Basin Management Plans under the Water Framework Directive to tackle diffuse pollution to water.

Also the Water Framework Directive requires an integrated and collaborative approach to planning and managing improvements in water quality across river basin districts and catchments. However, improvements in water efficiency can result in changes in the characteristics of wastewater with direct impact on the biodegradability and treatability of effluents. Changes in effluent characteristics also have implications for drainage systems within industrial sites, and may impact the public sewerage system. This presentation highlights the potential effects of water saving initiatives and the implications for wastewater treatment and ultimate disposal.

Here at CookPrior we have access to the technologies and management techniques to achieve those targets. CookPrior take a methodical approach to auditing all sources of water coming into and going out of processes. The next step is to match usage with the minimum water quality. Then CookPrior perform an integrated water management analysis. They do this by reviewing the findings with you to identify opportunities and targets where the use of fresh water can be reduced and where alternative raw water supplies can be used. They also look at similar opportunities for minimising effluent production and water reuse.

Starting with low costs solutions - washing wagons with freely available rainwater is one option - then moving onto more capital intensive sources or disposal methods, CookPrior build up clear opportunities for taking costs out of the business and putting margin straight back onto the bottom line.

What was the answer?

A summary of water savings from current and recent industrial and commercial water efficiency projects is given below.

  • Paper & board manufacture ~ 40%
  • Specialist Packaging (in progress) >50%
  • Specialist Local Dairy (in progress)>~30
  • Dairy Farming (rain water harvest completed) >90%
  • Vehicle Cleaning (rain water harvest & recycle ) 50%
  • Injection Moulding >10%

Barriers to Implementation

  • What standard does the recycled/ reuse water have to meet?
  • What impact will the changes have on:

    1. Environmental Permits (Discharge Consents)
    2. Combined effects on the sewer system
    3. Impacts (+ve or –ve) on other local industry
  • How to engage with the regulators

What was the outcome?

As part of the water efficiency projects, a “sustainability” test was applied. Had the changes made had a positive or negative effect on other parts of the supply chain or eco-system.

This identified a number of Waste Water System Vulnerabilities

  • Higher strength effluents

    1. Changes in sewage chemistry
    2. fate of compounds
    3. Changes in treatability

  • Lower sewerage system flows

    1. Solids deposition
    2. Increase in septicity
    3. Increase in odour and nuisance

In attempting to quantify these vulnerabilities, in the first instance Simple mass balance showed increased effluent strength (but same loads!). The Pennine Water Group also highlighted the potential for the negative impact from the “first foul flush” & the unknown dispersion characteristics on a receiving water course. There are also considerations from climate change which can exacerbate the changes made due to water efficiency measures.

The exercise also identified the potential to utilise sewers as extended tube reactors presenting the opportunity for more in-system treatment. The development of this, however, was felt to be something for a wider discussion between industrialists, sewerage undertaker, and regulators.

Data Needs
A review of the projects identified the following data needs in order to consider fully the impacts from the water efficiency measures:

  • quantities & flow characteristics
  • fate of:

    1. BOD,COD and BOD:COD ratio,
    2. known pollutants on the sites in question,
    3. emerging contaminants on the sites in question,

Stakeholder engagement
From the industrialists’ perspective in addition to the water efficiency benefits the modelling output can provide a platform to engage with major stakeholders such as:

  • Impacts on customers (CSR reporting)
  • Community / environment impacts (regulators)
  • Impacts on suppliers (water & sewerage undertakers)

Conclusions


  • Water saving initiatives can have impacts beyond the users site
  • Holistic approach to gain broader benefits along the whole supply/usage system
  • Quantification of these impacts by the use of (computer) models can help minimise the negative impacts


    • For more information or advice on how CookPrior can help in this area within your organisation please e-mail Kevin Prior or Diana Cook call +44 (0) 1890-818050