Quantitative image analysis for the characterization of microbial aggregates in biological wastewater treatment: a review

Abstract

Quantitative image analysis techniques have gained an undeniable role in several fields of research during the last decade. In the field of biological wastewater treatment (WWT) processes, several computer applications have been developed for monitoring microbial entities, either as individual cells or in different types of aggregates. New descriptors have been defined that are more reliable, objective, and useful than the subjective and time-consuming parameters classically used to monitor biological WWT processes. Examples of this application include the objective prediction of filamentous bulking, known to be one of the most problematic phenomena occurring in activated sludge technology. It also demonstrated its usefulness in classifying protozoa and metazoa populations. In high-rate anaerobic processes, based on granular sludge, aggregation times and fragmentation phenomena could be detected during critical events, e.g., toxic and organic overloads. Currently, the major efforts and needs are in the development of quantitative image analysis techniques focusing on its application coupled with stained samples, either by classical or fluorescent-based techniques. The use of quantitative morphological parameters in process control and online applications is also being investigated. This work reviews the major advances of quantitative image analysis applied to biological WWT processes.

Microbial-based evaluation of foaming events in full-scale wastewater treatment plants by microscopy survey and quantitative image analysis

“…Furthermore, the total filament length per total aggregate area ratio (TL/TA) was also determined (Amaral 2003), expressing the ratio between filamentous and aggregated biomass in the AS system, and together with the above parameters can be used to diagnose sludge settling problems. In fact, these parameters have been already found helpful to assess AS system malfunctions (Mesquita et al 2008(Mesquita et al , 2011Costa et al 2013) such as filamentous bulking (with large contents of filamentous bacteria, thus high TL/Vol and TL/TA values) or viscous bulking (presenting large contents of microbial aggregates, thus high TA/ Vol values). Therefore, it was expected that these parameters would also be useful in assessing foaming occurrences.…”

Evaluation of Anionic and Cationic Pulp-Based Flocculants With Diverse Lignin Contents for Application in Effluent Treatment From the Textile Industry: Flocculation Monitoring

“…Evolution with time of floc size and their structure can also be monitored by image analysis, which is considered as one of the easiest and the most direct measuring technique including image capture using a digital camera coupled to a microscope and its processing (Costa et al, 2013). However, this methodology requires preparation and manual selection/evaluation of a large number of samples (particles) over time in order to obtain data regarding flocculation kinetics.…”

Control of biogas production process by enzymatic and fluorescent image analysis

“…The images constitute a sum of pixels, which, after computer processing and analysis, allow the extraction of rigorous morphological quantitative data. Computers can extract quantitative information better than humans and may reduce the bias in image interpretation [15].…”