What's New
News & Updates
Feb
29

Visy's new retail paper bags...

Feb
22

Closing the loop...

Feb
15

AFPA'S new CEO...

Feb
15

Cadbury reduces packaging for Easter...

Feb
15

UK's Tesco rolls...

View All
Upcoming
Events
Meetings
Training
Webinars

Sep 29-Oct 1, 2024

Chemeca 2024: Lead the Change

Gold Coast, Queensland, Australia

Maximising Wastewater Treatment Plant Capacity with Increased Chemical Oxygen Demand (COD) load

Kia Hau (Wesley) Chan
Mill Chemist, Visy Pulp & Paper 3&6, Smithfield

Keywords: Wasterwater Treatment, COD, Anerobic, Aerobic, Sulphide

The design of the Wastewater Treatment Plant (WWTP) on Visy Paper’s Smithfield site was carried out in 2008 to comply with discharge limits. Due to process modifications, the characteristics of wastewater to the treatment plant has drastically changed over the past decade. With the current treatment facilities and stages, the influent Chemical Oxygen Demand (COD) has exceeded the design loading for the WWTP. This situation resulted in overloading of the anaerobic treatment stage and has cascading effects onto the latter stages, namely in the form of residual COD, sulphide and suspended solids (SS) in effluent. The objective of this study was to investigate ways of maximising treatment capacity through the high-rate anaerobic reactor and aeration system. The significance of the findings has had major impacts on compliance with the trade waste agreement and the stability of plant operations.

The methodology began with an assessment of the increased COD loading to the WWTP. The focus was shifted to the wastewater treatment plant to assess all treatment stages. This was done to determine the individual capacities and the feasibility for higher COD removal. Based on the outcome, several options for upgrades were developed, and a feasibility study was undertaken to determine the most suitable solution. Increasing the aeration capacity was selected based on economic and logistical feasibility. Detailed design was completed in April 2021 and commissioning of the upgraded system began in July 2021. Optimization work has been done over the following months to maximise sulphide and COD removal.

With a higher COD load entering the WWTP, a proportion of the influent is bypassed to the flash aeration system resulting in incomplete oxidation of sulphide and high residual COD in the effluent. To effectively achieve compliance with discharge limits, an upgrade of the aerobic system was completed to increase the aeration capacity by 40%. This has allowed further sulphide removal and COD reduction in the aeration system, achieving effluent compliance. Consequently, this upgrade has brought a new challenge as the higher biological removal capacity has resulted in the generation of more solids in the aeration system. Future studies will be undertaken to manage this increased solid loading in the effluent.


ALLANRussell

Wesley (Kia Hau) has completed his bachelor of degree in Chemical and Bio-molecular engineering from the University of Sydney in 2019. His journey in the pulp and paper industry embarked with a 6 months placement program from the university. His final year thesis was orientated around the placement on water management and clarification capacity at the Botany mill. From there, he was also involved in an advanced engineering project that focused on boiler and steam optimisations.


Upon finishing his undergraduate degree, he joined VISY as the mill chemist at the Smithfield site focusing on paper machine chemicals management, chemical trials, cost controls and process improvements. He then transitioned into his current role at the wastewater treatment plant. His primary focus is on performance monitoring and continuous process improvement across the plant. He was also involved in some of the capital projects planning and execution to maximise the treatment capacity.