InterLinc Home Page lincoln.ne.gov  
Health Logo  
Lincoln-Lancaster County Health Department
Environmental Public Health

Pollution Prevention


Identifying P2 Opportunities

So—you've decided that pollution prevention is a policy your business wants to live by. How do you start to identify the opportunities for reducing pollution at the source? Begin with a wastestream analysis. This activity consists of:

  1. counting and characterizing your processes,
  2. determining what and how much material is going in and going out of each process (assessing input and output or conducting a mass balance analysis), and
  3. determining how you can minimize or prevent the loss or wastage of those materials.
Counting Processes

The first step in your wastestream analysis is to count the processes included in your business. By breaking down the various operations into their component steps, you can more easily evaluate where waste is being generated and therefore how it can be prevented.

You may be surprised when you realize how many separate operations are contained in any business. For example, a service station could perform refueling operations; oil, lube, and antifreeze changes; engine work; brake work; and minor body repair. Each of these services involves separate materials that are received, stored, used, spilled or otherwise lost in the process, or discarded. Each step, therefore, presents you with different challenges and different opportunities for controlling pollution.

The same principles apply to manufacturing. Processes include component fabrication, assembly, finishing, and packaging. In the area of health care—such as dentistry—restorative procedures, prosthetics, radiography, and surgery each involve a series of special steps and procedures.

Once you have identified each process, identify each component of that process. In our service station example, refueling involves the receiving of bulk fuel and fueling individual vehicles. An oil change includes draining the used oil, wiping off oily parts or hands, and adding fresh oil from a container.

To prevent pollution, you need to know precisely what is happening to all of your materials while they are in your possession. By recognizing each different process in your business and breaking down the component steps in each process into smaller steps you can begin to track where materials become wastes. Tracking where they become wastes will help you determine how to minimize or prevent their production.

Assessing Input and Output

The second step in wastestream analysis—assessing input/output or mass balance. You will need to develop a "database" of the inputs to and outputs of each process. Ultimately, for each input or raw material that you regularly purchase or store, you should have the following information:

Your output database should have the following information for each waste that leaves your facilities, whether in liquid, solid, or gaseous form—

Process Flow Diagram

An easy way to visualize inputs and outputs is through a process flow diagram (see figure).

Define your process to include not only the process itself, but also the storage and handling of raw materials before the process as well as the storage and handling of finished materials and wastes after the process. The intent of the diagram is to illustrate all input points at which raw materials enter the process and all output points at which products or by-products leave the process.

Remember to include all output points. These are not always obvious. Output points can take a number of forms including spills, evaporated liquids, spent chemicals, unusable raw materials, and substandard or unusable products. All of these should appear on your flow diagram.

You can use this diagram as the basis of a materials accounting effort. Materials account allows you to estimate the magnitude of inputs and outputs related to the various processes in your business. This is the next step to identifying pollution prevention opportunities.

Materials Accounting

When identifying pollution prevention opportunities, you need to know how much material becomes waste. Materials accounting will help you determine how much toxic material ends up as by-product.

By-product is material that does not go directly into the manufacture of a product. For example, material in a chrome-plating operation that does not adhere to a part is by-product. (Product does not necessary mean "final product"; it may be a part used in another product—a bumper for a car.) By-products can include spills, evaporated liquids, spent chemicals, unusable raw materials, and substandard or unusable products. All of these by-products should appear on your flow diagram.

For example, the by-products of a plating bath include evaporation, spills, and runoff. When you see material dripping off a piece, you may not realize how much by-product you have. Nonetheless, to recognize cost-effective toxic reduction opportunities, you need to know how much by-product each process produces. (You can more easily modify some processes to reduce waste than you can others.) Materials accounting will help you. A Working Materials Accounting Formula

A simple formula lets you do materials accounting quickly. This process involves three steps:

  1. Determine how much material you use in a process.
  2. Determine how much of the material is actually applied onto or into the product.
  3. Determine how much of the material, if any, is converted by a chemical process into a benign or nontoxic substance. (You might need to consult a chemist.)

Do not count as by-product the material that stays on or in the product and the material that is converted in a chemical reaction to a nontoxic substance. That is, these substances will not leave your business as toxic emissions. Therefore, you may add these amounts together and subtract that sum from the amount of materials used in the process. The resulting figure is the amount of by-product the process produces.

The formula is:

Use - (Applied + Converted) = By-product

For example, assume that a process uses 10 ounces of nickel-plating solution. Three ounces of the solution adheres to the product, and none is converted by chemical reaction. This process produces 7 ounces of by-product: 10 - (3 + 0) = 7. To determine how much of a certain input material is converted to by-product in your processes, add up the by-products of all processes that use that material.

Mass Balance

A more complex and time-consuming process is a mass balance. This calculation indicates whether all material used adds up to the amount of material input. Add up the amount of material that is used in the product, that becomes by-product, and that accumulates in the production unit (such as a plating bath or a collecting tub). Compare that sum with the amount of material input:

Inputs = By-products + Products + Accumulated

Both sides of the equation should balance. If you have input 20 gallons of material, the sum of the by-product, the material in or on the product, and the material accumulated in the unit should equal 20 gallons. Because of the time-costs of performing this audit, you may wish to reserve this calculation for key production units and specific time frames.

Pollution Prevention Opportunities

Knowing where your business produces the greatest amount of by-product will help you determine what to do to reduce toxic waste emissions. You will be able to make cost-effective pollution prevention and toxic use reduction decisions based on facts and not based on guesswork.

Knowing where wastes come from helps you determine what changes you will need to make to reduce waste. If, for example, you notice that a great amount of material is lost in baths due to spills, drips, and evaporation you can modify equipment to capture these lost materials and reintroduce them to the production line.

Some P2 solutions will be simple and inexpensive. Yet they could save you vast amounts of money. Other solutions are less obvious. However, using wastestream analysis processes you should be able to discover and eliminate many sources of waste and save yourself money.


InterLinc City of Lincoln Departments Category Location

Health Environmental Public Health Environmental Quality