WASTEWATER

By Rick Lallish

What are the two methods or operational modes of membrane biologic reactor treatment units?

A. Inner-Outer

B. Serial-Parallel

C. Over-Under

D. Internal-Sidestream

Answer: D. In areas where space is very limited or water reuse is necessary, membrane bioreactor treatment is a viable alternative. MBRs use either internal treatment (the unit is installed within the aeration basin) or sidestream treatment (the unit is a separate module). Many activated sludge plants can be modified to accommodate an MBR module. MBRs are unique in that no clarifier is necessary. The effluent is removed by permeating through the membranes, with pore sizes as small as 0.01 micrometers. Most solids and pathogens cannot to pass through the membrane and remain in the basin. Filamentous and settling problems are eliminated by the absence of a clarifier. Effluent BOD, TSS and ammonia may be less than 1 mg/L in most cases.

More information may be found in the OWP, CSU-Sacramento textbook Membrane Bioreactors Field Study Training Program.

DRINKING WATER

By Drew Hoelscher

Starting in 2027, community water systems serving 10,000 or more people must distribute a Consumer Confidence Report how many times per year?

A. Once

B. Twice

C. Three times

D. Four times

Answer: B. The U.S. EPA finalized revisions to the Consumer Confidence Report Rule in accordance with the requirements of America’s Water Infrastructure Act of 2018. One of the main revisions requires all community water systems serving 10,000 or more people to distribute a CCR twice a year. The reports are distributed on July 1 and Dec. 31. More information on the revised CCR rule can be found at epa.gov/ccr/consumer-confidence-report-rule-revisions.

About the author(s)

Rick Lallish is water pollution control program director and Drew Hoelscher is program director of drinking water operations at the Environmental Resources Training Center of Southern Illinois University Edwardsville.