NC Water/Wastewater Operator case studies
NC Water/Wastewater Operator · Put your knowledge to work in context.
North Carolina requires the people who run drinking water and wastewater systems to hold a state certification, and the NC Water/Wastewater Operator Certification exam is the assessment that stands between a candidate and that credential. The exam is organized around four practice areas: water treatment, water distribution, wastewater treatment, and wastewater collection. The NC Water/Wastewater Operator case studies are 5 cases and about 3,341 words.
1Filter Effluent Creep and a Sinking Finished-Water pH
Your 6 MGD conventional plant treats a surface water with raw turbidity of 14 NTU and total alkalinity of 30 mg/L as CaCO3. Alum is fed at 32 mg/L and there is no other coagulant, polymer, or pH adjustment.
676 words, about 3 min2Chloramine Residual Collapse on a Dead-End Street
Your distribution system is fully chloraminated, with 0.9 mg/L total chlorine leaving the plant at a Cl2 to NH3-N weight ratio of 4 to 1. In the Elm Street area, 3,800 ft of 4-inch cast iron dead-ends with very low flows and an estimated water age of six days, total chlorine has fallen to 0.15 mg/L.
648 words, about 3 min3Rising Clarifier Blanket and an SVI of 290
Your 2.5 MGD activated sludge plant has one 1.2 MG aeration basin with fine-bubble diffusers and 4,200 mg/L MLSS. Over two weeks the secondary clarifier blanket has climbed from 2.5 ft to 7 ft.
648 words, about 3 min4High-Level Alarm at the Ash Street Lift Station During a Storm
Rain began at 21:00. Ash Street lift station serves 1,900 connections with a 6-ft diameter wet well, 11 ft from low water to overflow, and two constant-speed 350 gpm pumps on alternation.
718 words, about 4 min5CT Shortfall in a Poorly Baffled Clearwell
Your 3.5 MGD surface water plant disinfects with free chlorine and a single unbaffled 200,000-gallon clearwell. At peak flow the theoretical detention time is about 82 minutes, and a tracer study established a baffling factor of 0.30.
651 words, about 3 min