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Material balances

During this step detailed material- and energy balances should be made in order to quantify the amount of waste, its costs and its causes. The balances will furthermore provide a baseline showing the resource consumption and waste generation before cleaner production.

How to make a material balance?: 

Determine how each input and output can be measured. Plan measurement for a normal production day, or record consumption/waste stream over a longer period. If an input or output cannot be measured, make a qualified estimate.

The material balance should be based on actual figures. Figures from work procedures, equipment specifications and other "how-it ought-to-be" figures are of no use.

For the selected focus area(s) the flow diagram(s) should be further elaborated, to ensure that all processes/activities are included, and that all inputs and outputs are listed on the diagrams.

Next, the data for making material and energy balances should be collected. This will require a lot of work and measurements. It can be necessary to install meters to measure the consumption of water and electricity. Quantifying the inputs and outputs is the only way to identify losses that normally go by unnoticed.


Energy balance

Making an energy balance can be even more complicated than the material balance. Instead of making an actual balance it can be very useful to make a survey of the inputs and the losses. For a steam supply system, you need to measure the amount of fuel used, the boiler losses, and estimate the heat losses from poorly insulated surfaces, steam leaks and discharged condensate.

Waste stream characterization

The waste stream characteristics consists of three parts:

  • Quantifying the waste streams (the figures should be obtained from the material balance);
  • Describing the content and the environmental impact of the waste streams; and
  • Assigning costs (e.g. value of lost materials and cost of treatment) of the waste streams.

Cause Analysis

Asking WHY and WHY?

The cause analysis is based on asking why. The four main questions are:

  • Why this waste stream? Why is this step needed?
  • Why such a high consumption of materials, chemicals and energy?
  • Why so much waste?
  • Why these properties of the waste? Why using this equipment and these process conditions?

Why discharge? Why not recycle?