ABC Wastewater Treatment Class II study guide
ABC Wastewater Treatment Class II · Work through your exam, one topic at a time.
The ABC Wastewater Treatment Class II credential is a mid-level operator certification for people who run conventional wastewater treatment plants and are ready to take on more process responsibility than a Class I role. It is typically pursued by operators who already have hands-on plant experience and want formal recognition of their ability to run primary and secondary treatment, manage solids, and keep equipment and reporting in line. The ABC Wastewater Treatment Class II study guide has 9 sections and about 2,641 words.
01Operator Safety and Health
Confined-space entry is the highest-stakes safety topic on this exam. Know the definition (limited entry/egress, not designed for occupancy, may contain a hazardous atmosphere), the permit-required entry sequence (permit, atmospheric testing before and during entry, attendant, entrant, rescue provisions), and the rule that testing happens from the outside moving inward and top to bottom.
313 words, about 2 min02Preliminary and Primary Treatment
Preliminary treatment protects downstream equipment: bar screens and comminutors remove large solids, grit channels or vortex grit units remove sand and eggshell material that would abrade pumps and clog digesters. Know grit removal design (velocity control so organics stay in flow while dense grit settles) and why grit belongs in a landfill, not a digester.
322 words, about 2 min03Secondary Treatment (Suspended Growth and Attached Growth)
Suspended-growth (activated sludge) biology converts soluble BOD into floc that settles. Master these control parameters: mixed liquor suspended solids (MLSS), mixed liquor volatile suspended solids (MLVSS, the organic fraction, typically 70–80% of MLSS), food-to-microorganism ratio (F/M), mean cell residence time/solids retention time (MCRT/SRT), sludge volume index (SVI), and dissolved oxygen.
315 words, about 2 min04Disinfection and Effluent Quality
Chlorine chemistry dominates. Free chlorine exists as HOCl and OCl⁻; HOCl is the far stronger disinfectant, and the HOCl fraction increases as pH drops (best around pH 6.5–7.5).
301 words, about 2 min05Solids Handling, Thickening, Dewatering, and Digestion
Solids handling begins with thickening: gravity thickeners (typical 4–6% for primary sludge), dissolved air flotation (for light biological sludge), and gravity belt or rotary drum thickeners. Thickening cuts volume and reduces downstream tank and digester sizing.
288 words, about 1 min06Pumps, Motors, Instrumentation, and Process Control
Centrifugal pumps move water; positive-displacement pumps (progressive cavity, diaphragm, peristaltic) suit sludge and chemical feed. Know the pump curve, system curve, operating point, NPSH, cavitation (noise, vibration, pitting, flow loss), and affinity laws: flow varies with speed, head with speed squared, power with speed cubed.
276 words, about 1 min07Maintenance, Troubleshooting, and Equipment Reliability
Reliability is built on preventive and predictive maintenance: lubrication schedules, vibration analysis, thermography, oil analysis, and alignment checks. Know the difference between preventive (scheduled), predictive (condition-based), and corrective (after failure) maintenance, and why predictive is preferred for critical assets.
261 words, about 1 min08Laboratory Analysis, Sampling, and Monitoring
Sampling integrity is the foundation: grab vs. composite (time- or flow-proportioned), representative sampling points, clean containers, preservation (cooling to 4°C, acidification for metals, no headspace for BOD/DO), and holding times (BOD 48 hours, TSS 7 days, pH analyze immediately).
284 words, about 1 min09Regulations, Reporting, and Records
The Clean Water Act and NPDES permit framework govern discharges. Know permit components: effluent limits (monthly average, weekly average, daily maximum), monitoring frequency, reporting (discharge monitoring reports, DMRs), bypass and upset provisions, and the concept of significant noncompliance (SNC).
281 words, about 1 min