ABC Biological Industrial Waste Treatment Operator flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

BOD5

Biochemical oxygen demand over 5 days at 20°C; measures biodegradable organic matter in wastewater.

COD

Chemical oxygen demand; oxygen equivalent of organic matter oxidized by dichromate; includes non-biodegradable organics.

F/M ratio

Food-to-microorganism ratio; mass of BOD applied per mass of MLVSS per day; typical 0.2–0.5 day⁻¹.

SVI

Sludge volume index; volume of settled sludge after 30 minutes per gram of MLSS; 80–150 mL/g indicates good settling.

MLSS

Mixed liquor suspended solids; concentration of solids in aeration tank; typical 2000–4000 mg/L.

SRT

Solids retention time (sludge age); mass of solids in system divided by mass wasted per day; controls nitrification.

Nitrification

Biological oxidation of ammonia to nitrite then nitrate by autotrophic bacteria; consumes alkalinity and oxygen.

Denitrification

Anoxic conversion of nitrate to nitrogen gas by heterotrophic bacteria; requires carbon source and low oxygen.

Primary clarifier

Settling tank that removes settleable solids; typical removal: 50–70% TSS and 25–40% BOD.

Equalization basin

Tank that dampens flow and load variations; provides mixing and typical HRT of 4–24 hours.

Grit removal

Preliminary treatment removing dense particles >0.2 mm to prevent abrasion and accumulation in downstream processes.

Trickling filter

Fixed-film biological reactor with wastewater trickling over media; organic loading 0.3–2.5 kg BOD/m³·d.

Aerated lagoon

Biological treatment basin with mechanical aeration; HRT 5–10 days; power density 1–3 W/m³.

MBBR

Moving bed biofilm reactor; uses plastic carriers with biofilm; fill fraction 30–70% for treatment.

Facultative lagoon

Lagoon with aerobic surface and anaerobic bottom; depth 1.5–2.5 m; loading 20–50 kg BOD/ha·d.

Pretreatment standards

Regulations limiting industrial pollutants (e.g., metals, cyanide) discharged to publicly owned treatment works.

Shock load

Sudden increase in flow or organic concentration; can upset biological treatment; mitigated by equalization.

Nutrient addition

Addition of nitrogen and phosphorus to industrial wastewater to maintain BOD:N:P ratio of 100:5:1 for biomass.

Anaerobic digestion

Biological decomposition of sludge in absence of oxygen; produces methane; reduces volatile solids 40–60%.

Sludge dewatering

Process (e.g., belt press, centrifuge) that removes water from sludge to produce cake with 15–30% solids.

Gravity thickener

Tank that increases sludge solids concentration from 1–2% to 3–6% by settling.

CT concept

Disinfection efficacy product of disinfectant concentration (mg/L) and contact time (min); typical CT 15–30 mg·min/L.

UV disinfection

Inactivation of pathogens by ultraviolet light; dose 30–40 mJ/cm²; requires low TSS and high UV transmittance.

Dechlorination

Removal of residual chlorine using sulfur dioxide or bisulfite; dose about 1 mg/L per 1 mg/L chlorine.

Confined space entry

Entry into a permit-required space; test oxygen (19.5–23.5%), flammables (<10% LEL), and toxics before entry.

H2S

Hydrogen sulfide; toxic gas with rotten egg odor; immediately dangerous at >100 ppm; monitor in sewers and digesters.

LOTO

Lockout/tagout; safety procedure to isolate energy sources during maintenance; verify zero energy state.

Composite sampling

Sample collected over time or flow; used for variable flows; refrigerate at 4°C; preserves sample integrity.

BOD5 analysis

Laboratory test: seed, dilute sample, incubate 5 days at 20°C, measure dissolved oxygen depletion.

COD analysis

Digestion with dichromate at 150°C for 2 hours; measure absorbance; mercury sulfate masks chloride interference.

TSS analysis

Filter sample through glass fiber filter, dry at 103–105°C, and weigh; VSS obtained by ignition at 550°C.

Fecal coliform

Indicator bacteria for fecal contamination; typical effluent limit 200 CFU/100 mL; analyzed by membrane filtration.