Process Engineering


Process Engineering - much of it is like accounting. Keeping track of materials and energy. Engineers often use mass and energy balances to analyze systems and to design and plan process equipment needs. The cardinal equation is: In - Out = Accumulation. This balance analysis can be applied to overall mass, to an element (e.g. carbon), to energy, and more. This technique is conceptually simple, but it can be powerful and invaluable in the work of waste process engineering. And it’s a “good practice” for any operating facility. Although it is somewhat artificial, do the mass balance for a typical state of operation. Document it and put in your records. This may be useful if you need to pull out a document to show to a regulator or insurance company.

Balances are usually accompanied by a pictorial representation of the process with simplified icons showing tanks, pumps, and other important equipment. See Figure XXX.

A spreadsheet style list of numbers can be printed on the same sheet with the pictorial representation. The stream compositions or flowrates are shown as rates. You have latitude in what units to choose: kg/hr, lb/day, etc. Whatever seems reasonable.

Process Equipment

Equipment is often subject to codes and standards. These rules are set by government agencies, insurance companies, and professional organizations. Even when there is no law about your equipment, you should follow industry standards to avoid liability risk in case things go wrong.

Equipment manufacturers sell set “off-the-shelf” equipment with set capacities and sizes. Often these are listed on the manufacturer’s website and prices are fixed. Pumps, filters, and agitators for mixing are in that category. Custom-made, or customized standard equipment, are not fixed price and you need to get a quote from the seller. What do you have to tell the seller? He or she will want as much information as possible, including intended operating conditions and capacity as well as utilities available in the facility (steam, cooling water, electrical outlets, etc.)

Process Validation

Once the treatment process is up and operating, you should test it to make sure it operates as intended before you start running it on a regular basis. Validating the process can give you peace of mind as well as being a great way to encourage any regulators to give you needed permits. The validation establishes that the process achieves some benchmark:

  • Destruction of microorganisms (to some level)
  • Destruction of target contaminants or compounds
  • Operating temperatures and pressures required to get to those destruction levels.