O&M Newsletter

O & M Newsletter headerEnviroNews banner: forest stream, lake cottage, landfill construction, autumn field, winter lakefront

August 2014

In this issue:



For Practice


Each month, For Practice pulls together sample questions to help Operators who are preparing for their certification exam.  Listed below are an assortment of practice questions reflecting a variety of subject matter that Operators may encounter on the exam.  The answers are included below. 

Judy Bruenjes, PE

Sr. Env Engineer, Maine DEP

207-287-7806 


1.    The unit of electrical potential is

a.     The coulomb

b.     The volt

c.      The amp

d.    The watt 

2.   The aeration basins of a conventional activated sludge treatment system have a total volume of 250,000 gallons and the MLSS concentration in that tank is 2,650 mg/L. The secondary clarifiers have a total volume of 155,000 gallons and an average sludge concentration of 5,300 mg/L. The return sludge concentration is 8,250 mg/L.  4If the operator wants to maintain a 12-day MCRT, approximately how many gallons of sludge should be wasted?  Assume the effluent TSS is negligible and need not be included in the calculation.

a.      4,200 gallons

b.      2,700 gallons

c.     15,000 gallons

d.      7,000 gallons 

3.   Which of the following should always contain a hazard and operability study?

a.       An emergency plan.

b.      The annual budget

c.       A DEP inspector’s report

d.      The O&M Manual 

4.    The most difficult type of solids to remove in a conventional secondary treatment plant are:

a.     Inorganic suspended solids        

b.     Organic suspended solids

c.      Inorganic dissolved solids

d.      Organic dissolved solids

 


New Technical Assistance Engineer

 I want to let you all know that I have hired Judy Bruenjes, P.E. to join our staff in the compliance and technical assistance unit.   Judy has taken the position formerly held by Dick Darling, who retired after 22 years of service with Maine DEP.  She will be providing technical assistance, serving as the coordinator for the EPA DMR QA program, and will serve as the DEP’s point of contact for the Operator Certification program. 

Judy received a B.S. in Engineering from the University of Michigan and M.S. in Civil Engineering from Northeastern University and is a Maine licensed Professional Engineer.  Previously she provided wastewater training and consulting services to operators and analysts of municipal and industrial systems, predominantly in the Southeast.  She has also worked in private industry with storm water treatment and environmental consulting, as well as with the Mass DEP’s Division of Water Pollution Control. 

I am excited to once again be able to provide the MEPDES license holders with technical assistance when needed.  So please feel free to give Judy a call at 287-7806, or drop her an email at judy.k.bruenjes@maine.gov and let her know what you need. 

Judy is looking forward to working with operators and analysts to provide skills for improved process control, as well as asset management, wet weather plans, and lab QA/QC. 

Sterling Pierce

Compliance & Technical Assistance 


Freshwater Ambient Water Quality Monitoring Project Update

Thanks to all of the dischargers that have participated in the Department’s recent request for ambient sampling in freshwaters for phosphorus and nitrogen.  We have had a very good participation rate (as of late August 63% of freshwater dischargers have requested sample bottles from our contract lab).  Even though the flows are higher than we would have wanted, the information will be very useful.  Once we have compiled all the data, we will be back in touch with all freshwater dischargers to update them on this issue.  We expect that will occur in November.

Brian Kavanah


Answers to For Practice:

1.    b.    The unit used to designate electrical potential is the Volt. 

2.    c.     15,000 gallons 

First determine the total pounds of sludge in the system (aeration basin + clarifier) using the “pounds” formula: 

Total Sludge =  Pounds sludge in aeration basin + pounds sludge in the clarifier

                     = (0.25 MG * 2,650 mg/L*8.34) + (0.155 MG * 5,300 mg/L * 8.34)  =12,377lb 

Next, use the MCRT formula to determine the pounds of sludge that must be wasted per day: 

MCRT = Total sludge in system/Total sludge removed from the system per day 

The total sludge removed from the system includes wasted + effluent TSS.  However since the effluent

TSS is very low, we can assume zero for this problem.  So the MCRT formula becomes: 

MCRT = Total sludge in system/Total sludge wasted per day 

Rearrange the MCRT formula to solve for Total pounds of sludge wasted per day: 

Total pounds of sludge wasted per day    = Total pounds of sludge in system / MCRT

                                                                 = 12,377 lb / 12 days

                                                                  = 1031 lb/day

 Not quite done yet.  The question asks for gallons wasted per day.  How do we convert from lb/day to gal/day? 

Since we know the return sludge concentration (8,250 mg/L) we can determine the gallons of sludge, again using the pounds formula: 

Pounds  = flow (MGD) * concentration (mg/L) * 8.34 

Rearrange to solve for flow: 

             Flow = pounds / concentration / 8.34

                     = 1031 lbs / (8,250 mg/L * 8.34) = 0.015 MGD

                     = 15,000 gal/day 

Phew!  The answer is 15,000 gallons per day must be wasted. 

3.   a.  the hazards and operability study determines which units in the plant are susceptible to different hazards (such as flooding, earthquake, hurricanes, etc.) and how the loss of those units will affect the operability of the facility as a whole.  This study is an important part of any emergency plan. 

4.   c.  Organic dissolved solids and organic suspended solids are absorbed and adsorbed by the microbes in a secondary treatment system and removed when those microbes settle out of the effluent.  Suspended inorganic solids usually settle very quickly and are also removed from the effluent.  Inorganic dissolved solids are not readily taken up by microbes and do not settle out of the effluent and, therefore, are more likely to pass through a conventional biological treatment system without being removed.


Staff Updates


We have three water related vacancies we are working to fill:

·        * one permit writer position vacated by Cindy Dionne in Augusta;

·        * one inspector position vacated by Stacy Beyer in Bangor;

·        * and one water quality engineer position vacated by Peter Newkirk in Augusta. 

We hope to have these positions filled soon.