Graf One2Clean Service & Odour Investigation

We recently carried out a service and call-out on a Graf One2Clean sewage treatment plant following reports of persistent bad smells.

A full electrical, mechanical and treatment-process inspection was completed. The plant was operational, with the aeration, settlement and pumped discharge phases all manually tested and found to be functioning correctly.

Graf One2Clean Inspection

Good aeration was present throughout the treatment zone and both solenoid valves were operating correctly.

The control panel and wiring were found to be in good condition, with the electrical readings within the expected range.

Hiblow XP-80 Blower Service

The system is fitted with a Hiblow XP-80 air blower. The blower was tested and found to be operating correctly, with no abnormal noise present.

• Supply voltage: 230V
• Air blower current: 0.28A
• Blower operating correctly
• Air lines in good condition
• Heavily contaminated air filter replaced

Air leaks were identified at the hose-tail connections. All connections were tightened during the service to restore secure air delivery.

Diffuser Cleaning & Aeration

Both diffuser assemblies were removed, scoured and cleaned as part of the service.

Each diffuser was inspected and found to be in good condition, with no rips or tears identified.

High MLSS & Sludge Levels

The main issue identified during the service was the excessive concentration of solids within the treatment process.

• MLSS reading: 85% – very dense
• Primary tank crust: 0mm
• Primary tank sludge: 500mm

The very high MLSS reading and 500mm of sludge within the primary chamber indicate that the treatment plant now requires desludging.

This excessive solids concentration is considered a likely contributor to the persistent odour and cloudy final effluent reported by the customer.

Cloudy Effluent & Cleaning Chemicals

The final effluent was cloudy at the time of inspection.

In addition to the high solids concentration, excessive use of harsh household cleaning chemicals, bleach and antibacterial products may negatively affect the biological treatment process and contribute to reduced effluent quality.

The customer has therefore been advised to reduce the quantity of harsh cleaning products entering the system where possible.

Soakaway Check

The outlet inspection chamber leading towards the suspected soakaway was inspected and cleaned.

Water was continuously introduced into the chamber for approximately 15 minutes to check whether the downstream drainage system would accept the flow.

No backing-up was observed during the test, suggesting that the soakaway is currently accepting water correctly.

Operating Phases Tested

All Graf operating phases were manually tested during the visit:

• Aeration phase – operating correctly
• Settlement phase – operating correctly
• Pump-out phase – operating correctly
• Both solenoid valves – operating correctly

No immediate mechanical or electrical repairs were required.

Maintenance Completed

• Air blower filter replaced
• Both diffusers removed, cleaned and inspected
• Leaking hose-tail connections tightened
• Electrical testing completed
• All three operating phases manually tested
• Both solenoid valves tested
• Inlet inspection chamber cleaned
• Outlet inspection chamber cleaned
• Treatment plant washed down
• Suspected soakaway flow tested

Desludging Recommended

The treatment plant should now be desludged as soon as reasonably practicable.

Reducing the excessive solids concentration should help restore better treatment conditions and may also reduce the reported odour and improve final effluent quality.

Following desludging, the odour and effluent quality should continue to be monitored.

Routine Servicing

Regular servicing allows sludge levels, MLSS, electrical components, aeration equipment and treatment performance to be monitored before developing issues begin to affect the operation of the plant.

We provide Graf One2Clean servicing, fault finding and sewage treatment plant maintenance throughout Scotland.