Why CDFU-Style Pure-Physical Separation Is Displacing Chemical Dosing in Industry

2026-10-09

Chemical dosing solved oily wastewater once, but it leaves hazardous sludge and unstable effluent behind. This piece explains how a cyclonic flotation unit combines centrifugal pre-concentration with fine-bubble attachment to remove oil without reagents,

Two Stages, No Chemicals: An Equipment Level Breakdown of a 105 m3/h Desalter Effluent Deoiling Package

2026-10-08

A PetroChina refinery in Southwest China runs desalter effluent through a coalescing pressure oil separator followed by CDFU cyclonic dissolved-air flotation, with no dosing point anywhere in the line. This piece breaks down the coalescer media and hydrau

Coal Mine Sewage: Why the 1980s Activated Sludge Plants Failed and What Replaced Them

2026-10-08

Low-strength, highly variable mine sewage starved the activated sludge and oxidation ditch plants built in the 1980s, and two-stage biological contact oxidation took over through the 1990s with better tolerance but poor nutrient removal. This piece covers

Anaerobic Digestion in Four Stages: Using the Chemistry to Diagnose a Reactor That Is Drifting

2026-10-08

Hydrolysis, acidification, acetogenesis and methanogenesis run simultaneously in a real reactor, and the stage that slips first tells you what went wrong. This piece works through each stage with its stoichiometric equations and energy yields, compares th

Where Conventional Oily Water Equipment Loses: Efficiency, Footprint and O&M Compared Side by Side

2026-10-08

Gravity settling, open flotation and conventional filtration keep failing audits for the same four reasons: weak removal of fine droplets, punishing footprint, unstable operation with heavy maintenance, and rigid structure. This piece sets those failure m

Reading a Wastewater Characterisation Report: The Solids Fractions That Actually Decide Your Process

2026-10-08

Total solids is a headline number; the split between volatile, non-volatile, biodegradable and dissolved fractions is what determines whether a stream belongs in a bioreactor, a separator or a chemical step. This piece defines the five fractions, uses foo

Dewatered Sludge Is Still Mostly Water: Choosing Equipment by Cake Solids Rather Than by Brochure

2026-10-08

Mechanical dewatering lands most sludges at 20% to 30% solids, and the binding form of the water is what sets that ceiling rather than any machine. This piece classifies the six common sludge types by compressibility, walks the four-stage treatment line,

Sequencing Batch Reactors: When One Tank Running Five Phases Beats a Full Continuous Treatment Train

2026-10-08

The SBR process compresses equalisation, biodegradation and secondary sedimentation into one vessel by replacing spatial plug flow with temporal plug flow, and it only became practical once automation arrived. This piece traces the history, lists what the

BOD5 at 20 Degrees C: What the Five-Day Number Measures, Where It Misleads, and How to Run It Properly

2026-10-08

The five-day BOD test is a centenary-old convention that measures microbial appetite rather than chemical mass, and it still drives process selection through the BOD/COD ratio. This piece covers why 20 degrees C and five days became standard, the benchmar

Residual Chlorine in Practice: From Tap Standards and Pool Limits to Dechlorination Before Reverse Osmosis

2026-10-08

Residual chlorine means three different things depending on whether it is free, combined or total, and each fraction has its own limit in drinking water, pools, foot baths and medical effluent. This piece sets out the standards side by side, compares DPD