Application of imaging techniques for monitoring flocs in activated sludge Humaira Nisar, Lee Xue Yong, Yeap Kim Ho, Yap Vooi Voon, Soh Chit Siang Department of Electronic Engineering, Faculty of Engineering and Green Technology Universiti Tunku Abdul Rahman, Kampar, Malaysia humaira@utar.edu.my , leexy4@mail2.utar.edu.my , yeapkh@utar.edu.my , yapvv@utar.edu.my , sohcs@utar.edu.my Abstract— Activated sludge process is commonly used for purification of waste water.. In this paper imaging techniques are used to monitor activated sludge flocs in waste water treatment plants (WWTPs). Monitoring the flocs includes study of floc morphology and quantification of flocs. This information can help in the prediction of abnormal events in WWTPs and may help in avoiding plant malfunction. Keywords; digital image analysis;image processing; activated sludge; flocs and filaments; WWTPs I. INTRODUCTION Waste water is purified through the activated sludge process; that is the most frequently used process employed wordwide. The flocs that are basically microbial aggregates are one of the major components of the waste water purification system. In settling phase, filamentous bulking and deflocculation may occur; these are the most common problems worldwide that occur when the ratio of filamentous bacteria to floc forming bacteria is too large causing decrease in settling ability and effluent quality deterioration. To avoid this problem, frequent observation of activated sludge is required and the conditions in the tank must be controlled accordingly [1, 2]. Traditionally sludge volume index (SVI) measurements provide macroscopic characteristics of the activated sludge, however this information gathering occurs with a delay, hence little or no time for precautionary measure is left once sedimentation problems take place [3]. Microscopic observations of waste water systems provide detailed information but is time consuming and subjective depending on the expertise of the analyst. Therefore an automated image analysis procedure for quick and objective analysis of sludge floc properties would be a major accomplishment in the fight against bulking problems to keep the plant in operation. Morphological characterization of flocs, play an important role in assessing the state of the activated sludge. Malformed flocs that are bulky and loosely packed prevent proper sedimentation of sludge. The carryover solids not only degrade the quality of the treated affluent but may also clog the filters later. A laser particle analyzer is commonly used to measure the distribution of size of particles in water related process. This method is generally conducted in a laboratory by the help of a batch type method. In addition a analyzing particles using lasers is an expensive procedure, that is difficult to maintain and cannot be used to measure the flocs morphology which is helpful in determining the state of activated sludge [8]. The image analysis techniques used for automated sludge analysis involve capturing microscopic images via a precise and accurate microscopy system that automatically stores the images for on-site or off-site processing [4, 5]. These images are analyzed using state of the art image processing and pattern recognition algorithms. Hence faster, accurate and reliable results can be expected. However success of the overall process lies in precise and accurate recognition and quantification of activated sludge flocs and filaments. In this study image analysis is used to investigate the size and shape of activated sludge flocs and to quantify them. The application of automated methods makes the procedure more objective and reproducible as compared to the traditional analysis via microscope that is a subjective process. II. MATERIALS AND METHOD In this work image analysis has been used to monitor activated sludge flocs. The overall method can be divided into two major steps: Image acquisition and Image analysis. Image acquisition involves 1) sample and slide preparation, and 2) image capture. Image analysis involves 1) image processing and 2) image analyses. A. Image Acquisition 1) Sample and slide preparation The samples of activated sludge were collected from the aerations basins of a waste water treatment plant located in a residential area that deals with the household effluents, and then brought to the laboratory for testing. This work is supported by UTAR Research Fund (UTARRF) grant funded by Universiti Tunku Abdul Rahman (No. IPSR/RMC/UTARRF/C1- 11/H03) 2012 International Conference on Biomedical Engineering (ICoBE),Penang,Malaysia,27-28 February 2012 978-4577-1991-2/12/$26.00 ©2011 IEEE 6