Iwa international Specialist Conference

Figures

figure 1: organic sludge production comparison between a controle line and an ozonated line at a same mass load.



figure 2: suspended non volatile matter mass balance (total outlet (sludge wastage included) vs total inlet) as a function of the reduction of excess sludge production

11.

Bio Thelys^: The Vivendi Water Systems sludge reduction process

Lucie Patria, Julien Chauzy, Paulo Fernandes. Anjou Recherche

Didier Crétenot, Jean-Pierre Levasseur. Vivendi Water Systems

Abstract

The key objective of sludge minimisation is to optimise the activated sludge biomass growth and/or to enhance the biodegradation of the residual biomass. It will therefore always be the association of a process for organic matter hydrolysis and/or a process for biomass stress together with a biological process (either aerobic or anaerobic).

The most well known process of sludge minimisation is anaerobic digestion.

The idea of all the processes that can be developed for sludge minimisation will focused on the reduction of the quantity of excess sludge leaving the wastewater treatment.
This paper will produce an overview of the technologies that can be associated to biological processes on wastewater treatment plants in order to gain sludge minimisation.
It will also be the opportunity for a presentation of one particular process developed by Vivendi Water Systems and Anjou Recherche : BIO THELYS^ . The principle of the process is to associate a process of thermal hydrolysis to the activated sludge basin on a plant. A temperature of 175°C and a pressure of 15 bars are applied to hydrolyse the activated sludge and make it more biodegradable. Thermal hydrolysis is set on a secondary recycling loop on the activated sludge basin.

The process was operated over a period of 1 year on a municipal plant with a capacity of 2 500 population equivalent.

BIO THELYS^ can reach from 50% to 75 % sludge reduction production.

The use of a thermal process such as thermal hydrolysis in BIO THELYS^ is also an opportunity to have a sanitation process for the remaining excess sludge. It could be particularly interesting in the case of slaughterhouses and the protection against BSE.

The paper will therefore include an overview of sludge minimisation technologies and a presentation of a new process BIO THELYS^ and its application on municipal and industrial sludge.
12.

REDUCTION OF SLUDGE PRODUCTION IN A MUNICIPAL WASTE WATER TREATMENT FACILITY
Carl Podella, Exec. V.P. – R&D, Advanced BioCatalytics Corporation

Chuck E. Rogers, Superintendent – Hill Canyon Treatment Plant, Thousand Oaks, California

ABSTRACT

A proprietary formulation of surfactants with an array of biologically active proteins, Accell™, has been tested as an additive to wastewater in a municipal wastewater treatment facility to evaluate its possible beneficial effects on its operation. Accell™ has been found to affect the basic metabolism of the activated sludge, resulting in accelerated uptake of nutrient without a concomitant increase in biomass. These dynamics not only result in a significant decrease in sludge production, but also improved sludge settling, reduced turbidity and reduced aeration costs.

The test facility is an activated sludge plant that treats 10.5 million gallons of wastewater per day in two separate operating trains. Sludge settling and Sludge Volume Index data shows a 25 – 40% reduction, indicating more rapid sludge settling in the secondary clarifiers. Polymer usage has been eliminated in one clarifier and reduced in the other. The improved settling has also resulted in reduced effluent turbidity.
The reduced sludge production is evidenced by the amount of sludge pumped from the secondary clarifiers, in both total pounds and flow (in gallons). The Waste Activated Sludge (WAS) flow decreased by 6.5% during the 1^st 45 days of the study, total dry pounds of sludge declined by 18.5%. While this could be attributed to wasting less sludge, data indicate the Total Suspended Solids levels of the Return Activated Sludge had also decreased by 13 – 14% for both operating units Accell™, and the Mixed Liquor Suspended Solids levels in the aeration basins also declined during this period. .
The trend (of solids reduction) carries through to the dissolved air flotation/sludge thickening and digester processes. Sludge solids, in terms of pounds per hour pumped from the Dissolved Air Flotation (DAF) unit to the anaerobic digesters, dropped by 15.71%. The volume of thickened sludge being pumped from the DAF to the digesters also fell by 18.72%. While the sludge volume pumped from the digesters to the belt press also dropped by 9.92%, this data should improve significantly as the effects of treatment with Accell™ works its way through the process. Since the sludge inventory in the digesters remains relatively constant, digester retention time, in terms of days, has increased by 13.42%.
Bench tests confirm results seen in field trials. Studies indicate a significant increase in the nutrient uptake rate, reduced biomass production and increased CO₂ being generated for the Accell™ treated component versus the untreated Control. The effects of Accell™ treatment closely resemble those studies conducted by Euan W. Low and Howard A. Chase, where an uncoupling of oxidative phosphorylation is accomplished using materials such as para-Nitrophenol

(End of Abstract)

13

Abstract submitted for the IWA specialist group on sludge Management International conference : BIOSOLIDS 2003 wastewater sludge as a resource
Innovative strategies for the reduction of sludge production in activated sludge plant : Case studies of the novel processes

Biolysis® O and Biolysis® E