Real-time monitoring of activated sludge flocs via enhanced mask region-based Convolutional Neural networks.

The functionality of activated sludge in wastewater treatment processes depends largely on the structural and microbial composition of its flocs, which are complex assemblages of microorganisms and their secretions. However, monitoring these flocs in real-time and consistently has been challenging due to the lack of suitable technologies and analytical methods. Here we present a laboratory setup capable of capturing instantaneous microscopic images of activated sludge, along with algorithms to interpret these images. To improve floc identification, an advanced Mask R-CNN-based segmentation that integrates a Dual Attention Network (DANet) with an enhanced Feature Pyramid Network (FPN) was used to enhance feature extraction and segmentation accuracy. Additionally, our novel PointRend module meticulously refines the contours of boundaries, significantly minimising pixel inaccuracies. Impressively, our approach achieved a floc detection accuracy of >95%. This development marks a significant advancement in real-time sludge monitoring, offering essential insights for optimising wastewater treatment operations proactively.

[Seasonal variation of phytoplankton community structure in the Tianhe Reservoir of the Daluoshan Mountain in southern Zhejiang Province, China and its indication to water quality]. / 浙南大罗山天河水库浮游植物群落结构的季节变化及对水质的指示作用.

To explore the association between phytoplankton community structure and water quality of the Tianhe Reservoir in Wenzhou, Zhejiang, we examined the phytoplankton and physico-chemical factors in the Tianhe Reservoir from February 2019 to January 2020. A total of 89 phytoplankton species belonging to 60 genera and 7 phyla were identified. The annual average abundance and biomass of phytoplankton were 2.02×105 cells·L-1 and 0.26 mg·L-1 respectively. Bacillariophyta was dominant in the whole year. Chlorophyta was dominant in spring and autumn. Cyanophyta was dominant in summer. Both Euglenophyta and Pyrrophyta appeared in the whole year. Cryptophyta appeared in autumn and winter. However, none of them was dominant due to their low abundance. The dominant species throughout the year were Melosira granulata, Synedra acus, Navicula cryptocephala, Asterionella formosa, Pseudoanabaena, Closterlum venus, Pediastrum duplex, Peridinium bipes, Dinobryon cylindricum and Cryptomonas ovata. Results of redundancy analysis (RDA) showed that water temperature, total nitrogen, CODMn and pH value were the main factors driving phytoplankton community structure in the whole year. According to the evaluation based on diversity indices, including Shannon index, Pielou evenness index, Margalef richness index and comprehensive trophic status index (TLI), water quality of Tianhe Reservoir is between oligotrophication and mesotrophication.