Plan cleaning for lamella clarifiers before you install them, because sludge on plates narrows channels and uneven flow follows. Suppliers describe online backwashing, automatic brush systems and regular washing, and practitioners warn that closely packed plates are hard to reach. Write the cleaning method into the specification, not the manual.

Accept That Plates Foul

A waterandwastewater.com overview says plates can accumulate deposits from the treated water, leading to fouling or scaling, and that regular cleaning protocols are necessary to prevent performance degradation. A Wikipedia entry says sludge flows down the plates leaving them dirty.

Both statements are general, and neither names a frequency. I’d set the first interval from the wastewater: oily and fibrous streams foul faster than mineral ones.

Ask Whether Backwash Is Built In

Wuxi Yosun’s product page lists online backwashing and regular cleaning of the sludge on the inclined plates among its features, and its model table shows a separate DN50 backwash connection on each unit. That indicates a plumbed system rather than a manual hose.

Ask how long a backwash cycle runs, how much water it uses, where that water goes, and whether clarified output continues during the cycle.

Compare Automatic Cleaning Systems

A Sulzer brochure for its Lamella settler recommends regular cleaning to avoid sludge accumulation and describes a robot, CleanBot, that cleans plates without personnel during normal operation. A US patent describes a frame running on rails above the pack with hollow brush tubes that are lowered and raised against the plate surfaces.

Those are examples from other makers. They show that mechanical cleaning exists, and I’d ask any supplier of lamella clarifiers whether it offers a comparable option for your size.

Plan Cleaning for Lamella Clarifiers Around Access

Wikipedia states that closely packed plates make cleaning difficult. A pack with no top access, no lifting points and no drain valve will be cleaned late or never.

Check the manway size, the clear space above the pack and the means for lifting a plate section. The best cleaning system is the one an operator can reach.

Use Water Jets for Biological and Sticky Solids

A practitioner answer on a water-engineering forum says lamella units need regular water jet cleaning, and warns that bacteria and biofilms can grow on plate surfaces, plugging channels and creating anaerobic zones that release methane and hydrogen sulfide.

That is a single practitioner’s account, so I’d treat it as a risk to check rather than a rule. Where the feed carries biological solids, I’d plan on jet cleaning plus an inspection port.

Log Fouling Like Any Other Control

Record a pressure drop or water level difference across the pack, the date and method of each cleaning, and the effluent turbidity before and after. A rising pressure drop with steady flow shows fouling before the effluent does.

Cleaning that nobody records can’t be improved. Use the log to lengthen or shorten the interval.

Mind Waste Streams

Backwash water carries solids and chemicals back to the plant. It has to go to the inlet, an equalization tank or a sludge line, and the return flow adds a short peak of load.

Ask where the supplier expects the backwash to go, and size the return so that it does not upset the flocculation step.

Write the Method Into the Specification

State the cleaning method, interval, water use and access requirements in the contract. Wuxi Yosun’s lamella clarifier page lists backwashing and plate cleaning among its features, and you can ask for the details. Choose lamella clarifiers whose cleaning plan you can describe in one paragraph.

Frequently Asked Questions

Q: Do lamella plates need cleaning?
A: Yes. Overviews note fouling and scaling, and Sulzer recommends regular cleaning to avoid sludge accumulation.

Q: What cleaning methods exist?
A: Online backwash, water jets, and automatic brush systems that run along the pack. Ask which your supplier offers.

Q: Why is cleaning hard?
A: Wikipedia says closely packed plates make cleaning difficult, so plan access from the start.

Q: What should I log?
A: Pressure drop across the pack, cleaning dates and effluent turbidity before and after.