1. Application of MATLAB Image Processing Technology in Sewage Monitoring System ABIN N A

2.  Mr. Huidan Cao and Mr. Yuming Shen from University of Shanghai for Science and Technology in Shanghai, China.  This paper was submitted in The Ninth International Conference on Electronic Measurement & Instruments in 2009.  As part of my seminar, I have reconfirmed their findings. Acknowledgement

3.  What is sewage treatment ?  What is Image Processing ?  How MATLAB can be used in Image Processing ? Introduction

4.  Sewage treatment is the process of removing contaminants from wastewater and household sewage.  It includes processes to remove physical, chemical and biological contaminants.  Its objective is to produce an environmentally safe fluid waste stream and a solid waste suitable for disposal or reuse (usually as farm fertilizer).  The size and number of bubbles nucleated in a water body depends on the history of the water body and type of suspended particles. Sewage Treatment

5.  Image processing is any form of signal processing for which the input is an image, such as a photograph or video frame; the output of image processing may be either an image or a set of characteristics or parameters related to the image. Image Processing

6.  Image Processing Toolbox provides a comprehensive set of reference-standard algorithms and graphical tools for image processing, analysis, visualization and algorithm development. MATLAB in Image Processing

7.  This paper puts forward the application of MATLAB image processing technology in sewage monitoring system.  The percentage of the bubbles on the surface of the water is got by functions in the image processing toolbox of MATLAB.  The automatic alarm will be raised when the percentage of the bubbles exceeds the setting value. Objective

8. The flow of operations Start Image reading Image binaryzation Treatment details Filling the bubbles Calculating the % of bubbles percentage >10% End Raise alarm Y N

9.  A Camera.  A computer installed with MATLAB.  An alarm. HARDWARE FACILITIES

10. Original Image

11.  Read the image taken.  imread -- read image from graphic file. The format of the function is “imread(filename, fmt)”  imshow – which displays the image. The format of the function is “imshow(Image)” READING IMAGE

12.  Threshold method is a simple and effective method for image segmentation.  Threshold is a value used to distinguish the pixel of the object and the background.  If the gradation of pixel is greater than or equal to threshold, the pixel belongs to the object; otherwise it belongs to background.  im2bw(Image, level) - “Image” is the input image and level is the threshold. IMAGE BINARYZATION

13. Image After Binaryzation

14. Image Comparison Original ImageBinaryzed Image

15. Treatment of Details  Small particles in figure which are caused by noise, not the bubbles, so they will impact the results  So they need to be removed  The edge of the bubbles is not smooth.  They need to be smoothened.

16.  Remove small objects and smooth the edge of big object. The function “imopen” is used.  Fill the small hole inside the objects and also smooth the edge of the objects. The function “imclose” is used.  Fill the bubbles, so that area can be calculated. The function “imfill” is used. Treatment of Details(cont.)

17. Image After Treatment

18. Image Comparison Binaryized ImageTreated Image

19.  The matlab function “bwarea” is used to calculate the area of the object in the image  This will return the area of the total amount of pixels whose gray scale is 1.  % of the bubbles = Area of the total amount of pixels whose gray scale is 1/Area of the whole image.  When the % exceeds a setting value, the alarm will be raised. CALCULATION OF THE AREA OF BUBBLES AND ALARM

20.  This sewage monitoring system gets the percentage of the bubbles after a series of processes that determine whether the amount of sewage exceeds the standard or not.  The device restricts the sewage emission of the factories in an scientific and effective method.  Thus it provides an accurate and fair way for enviromental administration. Conclusion

21.  “Application of MATLAB Image Processing Technology in Sewage Monitoring System” Huidan Cao and Yuming Shen in the 9 th ICEMI 2009.  “Practical Handbook on Public Health Engineering” by GS Bajwa.  “Water Treatment: Fundamentals and Practical Implications of Bubble Formation” by Scardina, Robert Paolo  Image Processing Toolbox™ help REFERENCES