Wastewater Pump Winter Checklist: Frost Protection From Priming to Shutdown

2026-11-11

Winter is when a wastewater pump fails, and the failures are rarely dramatic: thickened lubricant, a stiff packing, a casing split by ice. This checklist follows the working order of an operator, from the six checks before the first start through bearing

Sour Water COD: Why Sulphides and Emulsified Oil Must Be Removed Together

2026-11-11

Sour water COD is usually treated as one number and one problem, but sulphide and emulsified oil behave differently and reinforce each other. With a theoretical 1 mg sulphide to 1.6 mg COD ratio, and sulphide dissolved in the oil phase, the only workable

Carbon-Supported Ozone Catalysts: What the Support Changes in Advanced Oxidation

2026-11-11

Ozone reacts slowly with most organics and disappears within about twenty minutes, which is why advanced oxidation depends on a catalyst that converts it to hydroxyl radicals. This note compares the three catalyst families on activity, cost and deactivati

Jet Aeration Systems: Oxygen Transfer Efficiency, Alpha Value and Tank Layout

2026-11-11

A jet aerator separates two duties that diffused aeration performs with one device: oxygen transfer and tank mixing. That separation explains its high alpha coefficient, its ability to keep sludge in suspension with the air off, and its fit to cyclic proc

Tank Farm Drained Water: Two Separation Mechanisms in Series at 100,000 mg/L

2026-11-11

Drained water from a tank farm combines an oil load above 100,000 mg/L with an emulsion fine enough to defeat bubble capture, and no single unit covers both. The answer is a division of mechanisms: a cyclonic coalescer grows the droplets, then cyclonic di

Food-to-Mass Ratio and Dissolved Oxygen: Why Extra Aeration Can Worsen Effluent

2026-11-11

More dissolved oxygen does not mean better treatment. In an aerobic system the useful oxygen level depends on the food-to-microorganism ratio, and at low F/M a high dissolved oxygen concentration accelerates endogenous metabolism until the sludge defloccu

Which Metals Catalyse Ozone: d-Block Chemistry Behind Catalyst Selection

2026-11-11

Catalyst selection for ozone duty is usually argued from test results, but the useful screening happens earlier, in orbital matching, coordination geometry and accessible oxidation states. This note explains why the d block dominates redox catalysis, why

When Ammonia Nitrogen Exceeds Total Nitrogen: Six Steps Where the Analysis Drifts

2026-11-11

Total nitrogen should always exceed ammonia nitrogen by construction, yet the two results invert often enough that laboratories treat it as routine. The cause is almost always procedural: holding time, an ammonia-bearing laboratory, reagent water, incompl

Reverse Osmosis Membranes: Transport Models, Fouling Diagnosis and Operating Limits

2026-11-11

An RO membrane rejects ions, colloids and high-molecular-weight solutes, but the rules that keep it alive are set by transport physics and by how fouling is diagnosed. This note walks through the three classic transport models, the flux equation that ties

Chlorine Dioxide in Water Treatment: Oxidising Strength, Dosing Limits and By-Products

2026-11-11

Chlorine dioxide attacks by electron transfer rather than substitution, so it disinfects without forming trihalomethanes, and it keeps working where ammonia and high pH would consume free chlorine. This note covers the molecular reasons for that behaviour