Conference Papers | 2009 Conference Papers

BIOSOLIDS BELT PRESSING – THE TRIALS AND TRIBULATIONS OF SEEKING BETTER PERFORMANCE

David Greaves, Coordinator Black Rock Water Reclamation Plant, Barwon Water

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INTRODUCTION
Black Rock water reclamation plant is the largest plant of its type operated by Barwon Water in Geelong, Victoria and services approximately 250,000 customers. The plant is an Intermittently Decanted Extended Aeration (IDEA) plant, with an average dry weather capacity of 70 ML/day and a peak wet weather capacity of 210 ML/day. The treatment process consists of coarse screening to 65mm followed by fine screening down to 3mm. From here the influent goes to four 25 ML biological treatment tanks which operate on a four hour treatment cycle consisting of two hours of aeration followed by one and a half hours of settling and 30 minutes of decanting. From
this process we have two outputs:

• Class C recycled water for use by connected customers or discharge from a 1.2 kilometre outfall to the ocean.
• Biosolids. During aeration cycles ‘mixed liquor’ (MLSS) is removed from the treatment tanks and belt pressed onsite. We

  currently produce 120 tonnes per day of dewatered biosolids from four Warman Belt filter press trains each with a 3

  metre width. Biosolids are then taken offsite via semi trailers for further drying and processing at Melbourne Water’s

  Western treatment plant as part of the short term biosolids management plan. Barwon Water’s long term biosolids  

  management strategy, an onsite thermal drying process at Black Rock, is currently under construction and is

  anticipated to be commissioned in early 2010.

Good maintenance ensures that the biosolids plant runs properly for the maximum amount of available time, however the question we kept asking ourselves was, ‘is the plant running at its most efficient?’

By way of a few mechanical failures in the belt filter press plant we have embarked on a series of trials involving recycled water, belt material, polymer choice and online monitoring equipment across the plant with the aim of producing the best possible final biosolids product. Additionally, with a new thermal biosolids drying plant presently being constructed onsite and commissioned next year, it is more important than ever that our dewatered biosolids have the best possible moisture content, consistency, and quality. Some of the trials provided improvement, some confirmed that what we were doing was the best possible, but the most important thing we achieved from the process was a far greater understanding of our plant and the belt filter press process.