Home Search | Sitemap Technique | Links | News | Training | Employment | Forums | Base
WHITE PAPER cerig.efpg.inpg.fr 
You are here: Home > Technique > Processes > Scientific report of the LGP2 > Papermaking and environment engineering > An activated sludge process for the biological treatment of urbanor industrial wastewater : from the design of an instrumented and supervised pilot towards a co-operative monitoring system           Update: July 20, 2011
Previous page Scientific report of the LGP2 (2006-2009) Next page
Previous page Next page
Researchers of the LGP2
(May 2011)
 
Grenoble INP-Pagora, International school of paper, print media and biomaterials
Join us
Laboratory of Pulp and Paper Science and Graphic Arts

I - Papermaking and Environment Engineering

I - 4 - An activated sludge process for the biological treatment of urbanor industrial wastewater : from the design of an instrumented and supervised pilot towards a co-operative monitoring system
Cindy Bassompierre, Marc Aurousseau, Agnès Guillet, Mohamed Aichi, Catherine Cadet, Jean-François Béteau

This PhD thesis is part of a project supported by the Grenoble INP since 2003. Its main objective is to create a platform [Figure 1] made up of a modular and adaptable semi-industrial pilot aimed at the development of tools and methodological approaches which can be configured for different urban and industrial applications. Two academic laboratories coordinate their competences in automatic and process engineering to successfully conclude this project: Laboratoire d’Automatique de Grenoble (LAG, UMR 5528) and Laboratory of Pulp and Paper Science and Graphic Arts (LGP2, UMR 5518). Industrial partners are also involved with this project: Centre Technique du Papier (CTP) lodges the pilot in its buildings and shares technical resources; Matussière & Forest Paper Group provides feedback on their experiments and access to their wastewater station (industrial wastewater to feed the pilot plant, sensors,...).

The activated sludge pilot setup   General scheme of the pilot equipment
Figure 1 - The activated sludge pilot setup   Figure 2 - General scheme of the pilot equipment

The activated Sludge Process is a biological treatment commonly used for treatment of urban and industrial wastewater. Its efficient application requires an effective control and supervisory system, and continuous enhancement of the process is still a research subject. Numerous laboratoryscale pilots have been constructed for many years but their small size weakens hydrodynamics influence on the treatment efficiency. This leads to difficulties with scale-up to real processes. Furthermore, the lack of direct on-line measurements on the process leads to an ineffective control structure, and optimization of this kind of process is thus problematic.

To answer these problems, a modular pilot setup has been developed to allow various studies and scale-up. All the components of an industrial biological treatment process are present in the pilot [Figures 1 & 2]:

The pilot setup has been sized according to two reference plants: an industrial process and an urban one. It is equipped with several elements, allowing uninterrupted operation and complete feedback information [Figure 2]: on-line continuous sensors, an automatic sampler, a refrigerated storage tank (prevention of wastewater degradation), a supervisor and an electrical control box. Control loops are implemented on the liquid level and on the dissolved oxygen concentration in the bioreactor. Residence time distribution (RTD) experiments on the bioreactor have been realized and compared with similar experiments on the reference industrial process (carrousel configuration). In both cases, the hydrodynamics modelling is similar and corresponds to a continuously stirred tank reactor that validates the hydrodynamic scale-up. Thanks to its modular conception, the use of baffles to created several compartments in the pilot allows us to study the effect of hydrodynamics on the treatment efficiency. Additionally, a simplified biological model has been developed. Based on the reference model ASM1 (Activated Sludge Model n°1) it achieves excellent accuracy both in dynamic and static mode [Figure 3], despite its simplicity (reduction of state variables and parameters, adaptation to industrial wastewater). This model has been validated with data from simulations of an urban reference station. It should be now validated with real measurements obtained on the pilot setup.

Reduced model validation on storm weather influences
Figure 3 - Reduced model validation on storm weather influences

Another part of the study is the development of software supported sensors to increase the knowledge of the process. Therefore, thanks to an observer of unmeasured state variables, micro-organism concentrations (heterotrophic biomass XBH and autotrophic biomass XBA) as well as organic matter concentration (XSS), hardly measurable, could be estimated through direct dissolved oxygen (SO) and nitrogen (SNH) measurements [Figure 4].

Observer convergence for an input flow disturbance
Figure 4 - Observer convergence for an input flow disturbance

Finally, the pilot appears as a very sophisticated tool that allows carrying out a wide range of tests on urban and industrial wastewater: follow-up of contaminant toxicity, hydrodynamic influence, treatment with fungi mixed with bacteria, biological modelling, control strategy design, effects of production process malfunctions. Moreover, this tool is suitable for industrial scale-up and will improve the understanding of both hydrodynamic and biological phenomena. Results obtained on modelling and observation allow the development of an aid-decision tool for the human operator. The improvement of process behaviour prediction will thus lead to a more efficient wastewater treatment.

Previous page Summary Next page
Previous page Summary Next page
Home | Technique | Links | News | Training | Employment | Forums | Base  
Copyright © Cerig/Grenoble INP-Pagora
Page make-up: A. Pandolfi