Upgrading an Existing Wastewater Treatment System

Upgrading An Existing Wastewater Treatment System


Upgrading existing on-site wastewater treatment system for a retreat centre.


The existing on-site wastewater treatment system was constructed approximately 7 years ago by a company no longer in business.

The treated effluent discharged to a surface water and was repeatedly failing to meet the strict conditions set-out in the discharge license. bioCycle™ were instructed to carry out a detailed assessment of the existing asset and the hydraulic / organic loadings to the plant, with a view to designing an upgraded system to meet the prescribed effluent standards.

Summary of Services:

  • Asset evaluation of existing system
  • Hydraulic and organic loading analysis
  • Detailed design of upgrade works
  • Mechanical and civil works


At the outset, a detailed study of the flows and loads to the existing plant were undertaken. This comprised of a desktop study (based on occupancy levels) and an on-site study (based on water metering and flow analysis). An assessment of the civil, mechanical and electrical assets of the existing plant was also undertaken.

The results of the assessments showed that the population equivalent was insufficient to deal with the current loading levels. Furthermore, the existing assets were insufficient to facilitate compliance with the discharge license at the loading levels, and a process re-design was required.

A consultation with the client’s representative was held to develop an engineered solution that incorporated the client’s additional requirements (e.g. extended desludging intervals) into the re-designed plant.

Following the detailed design of the upgrade works, a fee proposal was submitted to the client’s representative. Upon approval, works immediately commenced with bioCycle™ undertaking the civil works, the mechanical works and the electrical works. In order to minimise any disruption to the staff and patrons of the development, the sewers were kept live throughout the works.

The completed plant was immediately commissioned and subsequent chemical analyses of effluent samples have shown that the plant is meeting the requirements of the discharge license.


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