{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T01:10:05Z","timestamp":1760058605898,"version":"build-2065373602"},"reference-count":42,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2025,4,11]],"date-time":"2025-04-11T00:00:00Z","timestamp":1744329600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Processes"],"abstract":"<jats:p>Wastewater treatment plants (WWTPs) play a crucial role in treating sewage, which undergoes multiple treatment stages to ensure a safe treated effluent. However, any interference during these stages can compromise the final effluent quality. Such is the case of the overgrowth of the microcrustacean Daphnia spp., known to inhabit WWTPs, but with its presence in the decantation stage negatively impacting effluent clarification and further disinfection. This study aimed to evaluate how the effluent quality parameters influence the occurrence of Daphnia spp. in the secondary decanter of a WWTP. Wastewater monitoring data collected from 2017 to 2022 were analyzed. Firstly, as the COVID-19 pandemic occurred during the studied period, it was assessed whether the quality and load of the raw wastewater changed. Subsequently, an analysis was carried out using multivariate statistical methods for all the steps of WWTP. Comparing the periods before and during the pandemic, the raw wastewater volume decreased by 19.58%, and the BOD, COD, and TSS decreased by 37.78%, 16.86%, and 35.75%, respectively. These were the parameters affected the most. The statistical analysis revealed correlations between the presence of Daphnia spp. and specific effluent quality parameters, including raw wastewater BOD values below 500 mg L\u22121, treated effluent BOD values below 13 mg L\u22121, and pH levels exceeding 7.3. Additionally, BOD and pH were highlighted as critical parameters influencing their presence or absence.<\/jats:p>","DOI":"10.3390\/pr13041164","type":"journal-article","created":{"date-parts":[[2025,4,11]],"date-time":"2025-04-11T10:05:51Z","timestamp":1744365951000},"page":"1164","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Influence of Effluent Quality Parameters on Daphnia spp. Overgrowth in an Urban Wastewater Treatment Plant: A Multiyear Case Study Analysis"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0009-0008-1523-6960","authenticated-orcid":false,"given":"Pedro","family":"Esperan\u00e7o","sequence":"first","affiliation":[{"name":"Polytechnic University of Coimbra, Rua da Miseric\u00f3rdia, Lagar dos Corti\u00e7os, S. Martinho do Bispo, 3045-093 Coimbra, Portugal"},{"name":"Research Center for Natural Resources, Environment and Society (CERNAS), Polytechnic University of Coimbra, Bencanta, 3045-601 Coimbra, Portugal"}]},{"given":"R\u00f4mulo","family":"Egito","sequence":"additional","affiliation":[{"name":"Public Waters of Alentejo, Rua Dr. Aresta Branco, 7800-310 Beja, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6012-920X","authenticated-orcid":false,"given":"Ver\u00f3nica","family":"Oliveira","sequence":"additional","affiliation":[{"name":"Polytechnic University of Coimbra, Rua da Miseric\u00f3rdia, Lagar dos Corti\u00e7os, S. Martinho do Bispo, 3045-093 Coimbra, Portugal"},{"name":"Research Center for Natural Resources, Environment and Society (CERNAS), Polytechnic University of Coimbra, Bencanta, 3045-601 Coimbra, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2927-6129","authenticated-orcid":false,"given":"Ant\u00f3nio Lu\u00eds","family":"Amaral","sequence":"additional","affiliation":[{"name":"Polytechnic University of Coimbra, Rua da Miseric\u00f3rdia, Lagar dos Corti\u00e7os, S. Martinho do Bispo, 3045-093 Coimbra, Portugal"},{"name":"Research Center for Natural Resources, Environment and Society (CERNAS), Polytechnic University of Coimbra, Bencanta, 3045-601 Coimbra, Portugal"},{"name":"CEB\u2014Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1505-3749","authenticated-orcid":false,"given":"Carla","family":"Rodrigues","sequence":"additional","affiliation":[{"name":"Polytechnic University of Coimbra, Rua da Miseric\u00f3rdia, Lagar dos Corti\u00e7os, S. Martinho do Bispo, 3045-093 Coimbra, Portugal"},{"name":"Research Center for Natural Resources, Environment and Society (CERNAS), Polytechnic University of Coimbra, Bencanta, 3045-601 Coimbra, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2025,4,11]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1165","DOI":"10.1016\/B978-0-12-818634-3.50195-8","article-title":"Improving wastewater treatment plant operation by ammonia-based aeration and return activated sludge control","volume":"46","author":"Vasile","year":"2019","journal-title":"Comput. Aid. Chem. Eng."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"437","DOI":"10.1016\/j.jenvman.2007.03.008","article-title":"Sustainability of wastewater treatment technologies","volume":"88","author":"Muga","year":"2008","journal-title":"J. Environ. Manag."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Silva, J.A. (2023). 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