ESOH 405 – Water, Wastewater, Solid, and Hazardous Waste Treatment Fall 2016
Problem Set 2 – 50 points
- The weight of an empty evaporating dish is determined to be 37.628g. After a water sample is filter 96mL of the sample is evaporated from the dish. The weight of the dish plus the dried residue is found to be 38.002g. Compute the TDS concentration.
- A BOD test was conducted on a raw domestic wastewater sample. The wastewater portion added to each 300mL test bottle was 11.5mL, and the dissolved oxygen values were measured. Plot a BOD vs. time curve and determine the 5-day BOD value for each bottle.
| Bottle Number | Initial DO (mg/l) | Incubation Period (days) | Final DO (mg/l) | DO Drop (mg/l) | Calculated BOD (mg/l) | Calculated BOD5 |
| 1 | 8.4 | 0 | 8.4 | |||
| 2 | 8.4 | 0 | 8.4 | |||
| 3 | 8.4 | 1.0 | 6.2 | |||
| 4 | 8.4 | 1.0 | 5.9 | |||
| 5 | 8.4 | 2.0 | 5.2 | |||
| 6 | 8.4 | 2.0 | 5.2 | |||
| 7 | 8.4 | 3.0 | 4.4 | |||
| 8 | 8.4 | 3.0 | 4.6 | |||
| 9 | 8.4 | 5.0 | 3.8 | |||
| 10 | 8.4 | 5.0 | 3.5 |
- Estimate the 20 day BOD from Question 2 for bottles 1 through 10.
- What are the objectives of the Clean Water Act.
- Based on the flowing record of weekly low flows in a river, determine the MA7CD10 drought flow. Use the probability graph to show your answer. What is the 10 year, 7 consecutive day low flow in m3/s
| Year | Lowest 7day average flow m3/s | Year | Lowest 7day average flow m3/s |
| 1998 | 20 | 2006 | 26 |
| 1999 | 15 | 2007 | 50 |
| 2000 | 35 | 2008 | 54 |
| 2001 | 58 | 2009 | 70 |
| 2002 | 33 | 2010 | 45 |
| 2003 | 20 | 2011 | 40 |
| 2004 | 21 | 2012 | 62 |
| 2005 | 22 | 2013 | 48 |
| 100 90 80 70 60 50 40 30 25 20 15 10
|
| Yearly 7 consecutive day low flow m3/s |
- The discharge of the sewage treatment plant is 3.5 ML/d. The receiving stream had a BOD5 of 5 mg/L. The streamflow is 50 ML/d with a combined BOD5 of the sewage and the stream is 8 mg/L. What is the BOD5 from a poorly operating sewage treatment plant in mg/L?
- What components are part of a typical MCL violation that would appear in a newspaper? What is the point of a public notification when it comes to drinking water systems?