INFORMATION THAT MAY HELP

The engineer needs a basis for his design.  The usual stuff:

·        Quantity of flow

·        Occurrence of high flows

·        Biodegradable organic load

·        Peak organic load

·        Effluent requirements

·        If nitrification/denitrification is required

o       TKN load

The engineer fits a process between influent wastewater load and the effluent requirements using available information that may be limited or of poor quality.  Ideas on how to check (or adjust) the available data are offered. 

USEFUL TOOLS

A relatively simple Activated Sludge Mathematical Model is provided.  It is a convenient ways to estimate:

·        Carbonaceous Performance

o       Effluent Quality

o       Oxygen requirements

o       Sludge production

·        Nitrification Reactions

o       Oxygen requirements

o       Nitrates generated

o       Nitrification safety factor

·        Denitrification

o       BOD removed

o       Nitrates removed

The model can be applied to Flow-Through Reactors, SBR, Oxidation Ditch, MBR, or BNR designs.  For phosphorus removal, it does not estimate an effluent concentration, but It will add solids to the process influent to account for solids generated during phosphorus removal by biological phosphorus removal, ferric precipitation, or alum precipitation.                    

OLD TRICKS AND NEW TRICKS?

·        How much excess sludge does an activated sludge produce?  It can be a tricky subject.  You can use textbook information, but (a warning) you may be lead to the wrong answer.   The model does it for you.  Alternatively, an Excell spreadsheet is provided that estimates sludge production within about 10 percent.

·        BOD₅ measurement provides semi-quantitative information.  The fact that biochemical oxygen demand became a legal parameter has been detrimental to the Environmental Engineering Profession.  The mandatory information has limited engineering value.  How do you cope with it?  Is there something better? 

GUIDANCE INTENDED TO IMPROVE 
THE QUALITY OF THE PRODUCT

·        The engineer's objective is to meet the client’s needs, while striving to minimize construction cost and operating cost where feasible.

o       What process choices best meets the objective?

o       What is a reasonable safety factor?

o       What kind and degree of monitoring aid does the operator need?

               These are good questions, and I have a few thoughts.

INPUT THAT MAY HELP THE ENGINEER REDUCE RISK

   An engineering result is the culmination of the Engineer’s knowledge, experience, and professional judgment.  He is at risk for bad judgment.  Occasionally, the Engineer needs the support of Vendor Engineering.  To reduce risks to the project (and the Engineer), the Engineer must be able to check engineering offered by a Vendor.  A miscalculation by a Vendor is the responsibility of the Engineer (in a court of law).  Hopefully, some of the "Tools" offered will help the Engineer reduce risks.

   These "Tools" are some that I have developed for personal use through the years, and like most Engineering Stuff, new information develops, and "Tool" need upgrading.  I have attempted to keep the "Tools" up to date, but you will find that I am still using English units.  These "Tools" are not superior; they are "Tools" that I am comfortable with and find useful.  If you elect to try them, please apply  good judgment.  I think the "Tools" work well, but I developed them and probably take a lot for granted.  If you find a problem with a "Tool", please let me know.  You may find them limited and cumbersome, but I also hope that you find some value.