Academic Journal

Toward advanced management of sludge bulking: An explainable evaluation framework to quantify and improve large language model cognitive capabilities.

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Τίτλος: Toward advanced management of sludge bulking: An explainable evaluation framework to quantify and improve large language model cognitive capabilities.
Συγγραφείς: Xu B; School of Technology for Sustainability, Beijing Normal University, China., Fan N; School of Technology for Sustainability, Beijing Normal University, China., Zhang C; School of Technology for Sustainability, Beijing Normal University, China., Xu G; School of Technology for Sustainability, Beijing Normal University, China., Yu H; School of Civil Engineering and Transportation, Guangzhou University, China., Zeng H; College of the Environment & Ecology, Xiamen University, China., Tong R; DeepMind, Google, 1600 Amphitheatre Pkwy, Mountain View, CA, United States., Yu K; Beijing Originwater Technology Co. Ltd., Beijing, China., Yuan Z; School of Energy and Environment, City University of Hong Kong, Hong Kong, China., Ng HY; School of Technology for Sustainability, Beijing Normal University, China; Department of Civil and Environmental Engineering, National University of Singapore, Singapore. Electronic address: huanghy@bnu.edu.cn.
Πηγή: Water research [Water Res] 2026 Oct 15; Vol. 305, pp. 126492. Date of Electronic Publication: 2026 Jul 13.
Τύπος έκδοσης: Journal Article
Γλώσσα: English
Στοιχεία περιοδικού: Publisher: Pergamon Press Country of Publication: England NLM ID: 0105072 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1879-2448 (Electronic) Linking ISSN: 00431354 NLM ISO Abbreviation: Water Res Subsets: MEDLINE
Imprint Name(s): Original Publication: Oxford, Pergamon Press.
Ιατρικοί όροι (MeSH): Waste Disposal, Fluid*/methods , Sewage*, Large Language Models
Περίληψη: Activated sludge bulking is a globally prevalent operational failure in wastewater treatment plants (WWTPs), which demands timely, accurate human intervention, but the scarcity of specialist wastewater expertise poses a considerable challenge. Large language models (LLMs) potentially support bulking management by providing human-like cognitive capabilities. However, there is no explainable evaluation framework to quantify LLMs' cognitive capabilities' strengths and limits, and, crucially, inform how these capabilities can be improved for advanced sludge bulking management. Here, we developed an explainable evaluation framework, by establishing an open-access evaluation suite (280 tasks including real-world cases) with an LLM-rater (with ground truth in prompts to ensure evaluation reliability), to diagnose LLMs' cognitive capabilities of understanding, analysis, and practice. Under this framework, we found that performance was dominated by task type rather than LLM identity (DeepSeek-R1, GPT-4o and Gemini-2.0). Concretely, LLMs generally showed limited understanding capability on microscopy-based recognition (accuracy<54%) and microbial identification (normalized-scores:28-42%), and weak analysis capability for process-microbe interactions (normalized-scores:36-52%). Practice tasks were also challenging, with deficits across all cognitive capabilities, and had highest token demand among all task types. Guided by this explainable framework, we integrated a vision module with LLMs to improve visual understanding of key filaments, including Beggiatoa, fungi, and Nocardia (accuracy from 51% to 78%). In parallel, retrieval-augmented generation (RAG) was further employed to selectively enhance practice capability, with DeepSeek-R1, a thinking model, showing the largest gains in practice capability (69%). The RAG-enhanced DeepSeek-R1 (i.e., FilamentGPT) achieved the best overall performance (normalized-scores>80% for all, except microbial identification), and demonstrated practical feasibility for WWTP decision-support based on perspectives of 20 WWTP engineers. We attribute this advantage to its stronger ability to integrate retrieved knowledge into reasonable, plant-specific workflows. Collectively, this work established an explainable evaluation framework for LLMs in sludge bulking management, constituting a science foundation for LLMs evaluation. Informed by explainable framework, we also outlined (post-)training pathways (e.g., RAG, vision module) to selectively enhance cognitive capabilities of LLMs, which could democratize subspecialist-level expertise for wastewater treatment in WWTPs.
(Copyright © 2026 Elsevier Ltd. All rights reserved.)
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Contributed Indexing: Keywords: Filamentous microbes; Generative artificial intelligence; Inference; LLM-as-a-judge; Multimodal; RAG
Substance Nomenclature: 0 (Sewage)
Entry Date(s): Date Created: 20260723 Date Completed: 20260909 Latest Revision: 20260909
Update Code: 20260909
DOI: 10.1016/j.watres.2026.126492
PMID: 42492211
Βάση Δεδομένων: MEDLINE
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  Data: &lt;searchLink fieldCode=&quot;AU&quot; term=&quot;%22Xu+B%22&quot;&gt;Xu B&lt;/searchLink&gt;; School of Technology for Sustainability, Beijing Normal University, China.&lt;br /&gt;&lt;searchLink fieldCode=&quot;AU&quot; term=&quot;%22Fan+N%22&quot;&gt;Fan N&lt;/searchLink&gt;; School of Technology for Sustainability, Beijing Normal University, China.&lt;br /&gt;&lt;searchLink fieldCode=&quot;AU&quot; term=&quot;%22Zhang+C%22&quot;&gt;Zhang C&lt;/searchLink&gt;; School of Technology for Sustainability, Beijing Normal University, China.&lt;br /&gt;&lt;searchLink fieldCode=&quot;AU&quot; term=&quot;%22Xu+G%22&quot;&gt;Xu G&lt;/searchLink&gt;; School of Technology for Sustainability, Beijing Normal University, China.&lt;br /&gt;&lt;searchLink fieldCode=&quot;AU&quot; term=&quot;%22Yu+H%22&quot;&gt;Yu H&lt;/searchLink&gt;; School of Civil Engineering and Transportation, Guangzhou University, China.&lt;br /&gt;&lt;searchLink fieldCode=&quot;AU&quot; term=&quot;%22Zeng+H%22&quot;&gt;Zeng H&lt;/searchLink&gt;; College of the Environment &amp; Ecology, Xiamen University, China.&lt;br /&gt;&lt;searchLink fieldCode=&quot;AU&quot; term=&quot;%22Tong+R%22&quot;&gt;Tong R&lt;/searchLink&gt;; DeepMind, Google, 1600 Amphitheatre Pkwy, Mountain View, CA, United States.&lt;br /&gt;&lt;searchLink fieldCode=&quot;AU&quot; term=&quot;%22Yu+K%22&quot;&gt;Yu K&lt;/searchLink&gt;; Beijing Originwater Technology Co. Ltd., Beijing, China.&lt;br /&gt;&lt;searchLink fieldCode=&quot;AU&quot; term=&quot;%22Yuan+Z%22&quot;&gt;Yuan Z&lt;/searchLink&gt;; School of Energy and Environment, City University of Hong Kong, Hong Kong, China.&lt;br /&gt;&lt;searchLink fieldCode=&quot;AU&quot; term=&quot;%22Ng+HY%22&quot;&gt;Ng HY&lt;/searchLink&gt;; School of Technology for Sustainability, Beijing Normal University, China; Department of Civil and Environmental Engineering, National University of Singapore, Singapore. Electronic address: huanghy@bnu.edu.cn.
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  Data: Activated sludge bulking is a globally prevalent operational failure in wastewater treatment plants (WWTPs), which demands timely, accurate human intervention, but the scarcity of specialist wastewater expertise poses a considerable challenge. Large language models (LLMs) potentially support bulking management by providing human-like cognitive capabilities. However, there is no explainable evaluation framework to quantify LLMs&#39; cognitive capabilities&#39; strengths and limits, and, crucially, inform how these capabilities can be improved for advanced sludge bulking management. Here, we developed an explainable evaluation framework, by establishing an open-access evaluation suite (280 tasks including real-world cases) with an LLM-rater (with ground truth in prompts to ensure evaluation reliability), to diagnose LLMs&#39; cognitive capabilities of understanding, analysis, and practice. Under this framework, we found that performance was dominated by task type rather than LLM identity (DeepSeek-R1, GPT-4o and Gemini-2.0). Concretely, LLMs generally showed limited understanding capability on microscopy-based recognition (accuracy&amp;lt;54%) and microbial identification (normalized-scores:28-42%), and weak analysis capability for process-microbe interactions (normalized-scores:36-52%). Practice tasks were also challenging, with deficits across all cognitive capabilities, and had highest token demand among all task types. Guided by this explainable framework, we integrated a vision module with LLMs to improve visual understanding of key filaments, including Beggiatoa, fungi, and Nocardia (accuracy from 51% to 78%). In parallel, retrieval-augmented generation (RAG) was further employed to selectively enhance practice capability, with DeepSeek-R1, a thinking model, showing the largest gains in practice capability (69%). The RAG-enhanced DeepSeek-R1 (i.e., FilamentGPT) achieved the best overall performance (normalized-scores&amp;gt;80% for all, except microbial identification), and demonstrated practical feasibility for WWTP decision-support based on perspectives of 20 WWTP engineers. We attribute this advantage to its stronger ability to integrate retrieved knowledge into reasonable, plant-specific workflows. Collectively, this work established an explainable evaluation framework for LLMs in sludge bulking management, constituting a science foundation for LLMs evaluation. Informed by explainable framework, we also outlined (post-)training pathways (e.g., RAG, vision module) to selectively enhance cognitive capabilities of LLMs, which could democratize subspecialist-level expertise for wastewater treatment in WWTPs.&lt;br /&gt; (Copyright &#169; 2026 Elsevier Ltd. All rights reserved.)
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  Data: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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