GRAF One2Clean Sewage Treatment Plant Service – Tranent, East Lothian

We recently completed a full service on an 18-population GRAF One2Clean sewage treatment plant in Tranent, East Lothian.

The GRAF One2Clean was operational at the time of our visit, but the service identified several maintenance issues including a heavily contaminated blower filter, multiple air leaks and an elevated concentration of biological solids within the treatment process.

A full electrical, mechanical and treatment-process inspection was completed, including testing of the air blower, diffusers, solenoid valves and complete treatment cycle.

18-Population GRAF One2Clean Sewage Treatment Plant

This is an 18-population GRAF One2Clean system consisting of two treatment tanks. The complete system was inspected as part of the scheduled service, including the external control equipment, air delivery system and internal treatment components.

HIBLOW HP-200 Air Blower Service

The sewage treatment plant is fitted with a HIBLOW HP-200 air blower.

Electrical testing recorded a blower running current of 1.350A. The blower itself was operating correctly, although the air intake filter was found to be heavily contaminated.

The contaminated filter was removed and replaced as part of the service.

Some vibration was also present within the blower enclosure. This was found to be transferred through surrounding cables and components rather than originating from an internal blower fault. The cables and surrounding equipment were repositioned as far as practicable to reduce the vibration.

Air Leaks Identified & Repaired

During inspection of the aeration system, multiple leaking air-line connections were identified.

These connections were rectified during the service to ensure the available airflow was being correctly delivered to the treatment tanks rather than being lost through leaking connections.

All Four GRAF Diffusers Removed & Cleaned

All four diffuser assemblies were removed from the sewage treatment plant for cleaning and inspection.

Each diffuser was thoroughly cleaned and individually tested. No splits, tears or other defects were identified within the diffuser membranes.

Once the diffusers had been refitted and the aeration system recommissioned, good fine-bubble air distribution was present throughout both treatment tanks.

MLSS Reading of Approximately 50%

An MLSS settlement test was completed to assess the concentration of biological solids within the treatment process.

The test recorded approximately 50%, with the mixed liquor visibly very thick. This indicates a high concentration of solids within the biological treatment zone.

The treatment plant is therefore due to be emptied/desludged to reduce the solids concentration and help maintain effective treatment conditions.

Wipes, Rags & Sanitary Products Removed

A considerable quantity of wipes, rags and sanitary products was also found within the sewage treatment plant and removed during the service.

Unlike toilet tissue, these materials do not readily break down within a sewage treatment system. They can accumulate around internal components and potentially interfere with airlift systems and the biological treatment process.

Only suitable biodegradable materials should be allowed to enter a domestic sewage treatment plant.

GRAF One2Clean Treatment Cycle Tested

Both solenoid valves were individually tested and the complete GRAF One2Clean treatment sequence was manually checked.

• Aeration phase – tested and operating correctly
• Settlement phase – tested and operating correctly
• Discharge / pump-out phase – tested and operating correctly
• Solenoid valve 1 – operating correctly
• Solenoid valve 2 – operating correctly
• Fine-bubble aeration – good throughout both tanks
• Final effluent clarity – good

The controller operating hours were also recorded during the service, with 14,486.63 total blower hours. Valve 1 recorded 13,474.63 hours and Valve 2 recorded 1,012 hours.

Service Work Completed

• Full electrical inspection completed
• HIBLOW HP-200 blower tested at 1.350A
• Contaminated blower intake filter replaced
• Multiple air leaks identified and rectified
• All four diffusers removed and cleaned
• All four diffusers individually inspected and tested
• Both solenoid valves tested
• Aeration phase manually tested
• Settlement phase manually tested
• Discharge phase manually tested
• MLSS settlement test completed
• Wipes, rags and sanitary products removed
• Final effluent condition checked
• Complete system returned to automatic operation

Desludging Recommended

Although the GRAF One2Clean was operating correctly following the service, the elevated MLSS reading means the treatment plant is now due to be emptied/desludged.

Reducing the accumulated solids will help restore more suitable treatment conditions and allow the biological process to continue operating effectively.

GRAF One2Clean Servicing in East Lothian & Across Scotland

Routine servicing of a GRAF One2Clean sewage treatment plant allows the blower, air filters, air lines, diffusers, solenoid valves, electrical controls and biological treatment conditions to be checked before developing issues result in poor treatment performance or breakdowns.

We provide GRAF One2Clean servicing, fault finding, repairs and sewage treatment plant maintenance across Tranent, East Lothian and throughout Scotland.

If your GRAF One2Clean is due a service, showing an alarm, producing poor effluent or experiencing aeration problems, contact Caledonia Environmental to arrange an inspection or service.