You manage an independent septic treatment facility at a university – waste wate

Question

You manage an independent septic treatment facility at a university – waste water from all university toilets is directed to your facility (a separate grey water facility handles all non-toilet water). The university has 23 buildings with an average of 6 toilets per building. There are total of 8500 faculty, staff and students at the university (each person flushes a toilet 3 times per day and is at university 5 days per week). All toilets are identical and use 1 gallon per flush. You must pre-treat all waste water with an enzyme that breaks down cellulose (paper)-one unit of this enzyme is defined as enough to treat 1 liter of waste water (ignoring any solids). The enzyme comes in bottles of 10000 units per bottle. You are budgeting for an average week (of 5 days), how many bottles of enzyme will you need per 5 day week? You can look on line for volume conversion or you can look at the back of the rim of a commercial toilet. Most have 1 GPF and 3.8 LPF printed on them. You’ll never forget once you see that a few times.

Explanation / Answer

Given that ;

There are total of 8500 faculty, staff and students at the university

Each person flushes a toilet 3 times per day and is at university 5 days per week

All toilets are identical and use 1 gallon per flush.

Now calculate the total water in flush:

8500 * 3 time / 1 day * 5 days / weak* 1 gallon / 1 flush

=127,500 gallon water

And 1 gallon = 3.8 litters

The convert the unit from gallon to litters as follows:

127,500 gallon water * 3.8 L/ 1 Gallon

= 484,500 L

And given that;

one unit of this enzyme is enough to treat 1 liter of waste water

The enzyme comes in bottles of 10000 units per bottle

Now calculate the number of enzyme:

484,500 L * one unit enzyme / 1 L

484,500 unit enzyme

Now number of bottles as follows:

1 bottle / 10000 units enzyme * 484,500 unit enzyme

= 48.45 bottles

= 49 bottles

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