This survey reviews the analysis of Active Sludge (AS) particles in wastewater or sewage water treatment plants. There are many methods followed for analysis of sewage water to monitor particles present in it. The samples from treatment plants are photographed with a microscope in order to view the particles. Analysis is done to improve the quality of water by treating the water according to the analysis report, so that water can be reused. The processes used to analyze the waste water keep developing as technology develops. Previously, manual analysis is done to get a report about particles present in waste water, but in recent times image processing makes the analysis process easier. A method that detects the unbranched filamentous bacteria length is proposed by researchers. In order to determine the curvature of an extended filament border, researchers have proposed some rotation invariant features. Previous research models are investigated for sludge volume index (SVI) of various active sludge wastes from waste water treatment plants. Analysis of images leads to measurement of parameters of both filaments and flocs present in waste water. The modelling of filaments and flocs based on the measured parameters can decide a method to clean waste water of treatment plants.
