Pollution tolerant protozoa in polluted wetland

Temperate urban wetland plankton community stability driven by environmental variables, biodiversity, and resource use efficiency: A case of Hulanhe Wetland

In this study, we explored the driving factors behind plankton community structure. Due to the rapid development of cities, the occupation and development of wetland resources have increased lately, making the urban wetland ecosystems unstable and degrading the ecological functions gradually. Understanding the driving factors behind plankton community structure has certain theoretical and guiding significance for the protection, sustainable development, and ecological restoration of aquatic biodiversity in urban wetland ecosystems. We set up 12 sampling points in the Hulanhe Wetland, with the continuous monitoring of plankton from April to August and October 2021. The eco-environmental factors, plankton community structure, biodiversity index, resource use efficiency (RUE), and Bray–Curtis community turnover value were analyzed. A total of 209 species of 91 genera, 42 families, 11 classes, 22 orders of phytoplankton, and 90 species of four classes of zooplankton were identified. The community structure was mainly composed of Bacillariophyta, Chlorophyta, Cyanophyta, Protozoa, and Rotifera. To explore the correlation between phytoplankton and zooplankton, a correlation study was performed. We found a stable feeding preference between phytoplankton and zooplankton. The key influencing factors were identified by ordinary least squares regression, and the main driving factors of plankton community structure were discussed. The results showed that the stability of the Increased biodiversity and resource utilization efficiency have led to more stable plankton communities. This stability pattern is also strongly affected by water temperature, pH and total nitrogen in the external environment. This study will be helpful in the restoration of damaged wetlands, which would be beneficial for the protection of urban wetland ecosystems.

Highly Enriched Anammox Bacteria with a Novel Granulation Model Regulated by Epistylis spp. in Domestic Wastewater Treatment

Anammox granulation is an efficient solution proffered to enrich slow-growing anammox bacteria (AnAOB), but the lack of effective granulation strategies for low-strength domestic wastewater impedes its application. In this study, a novel granulation model regulated by Epistylis spp. for highly enriched AnAOB was revealed for the first time. Notably, anammox granulation was achieved within 65 d of domestic wastewater treatment. The stalks of Epistylis spp. were found to act as the skeleton of granules and provide attachment points for bacterial colonization, and the expanded biomass layer in turn provided more area for the unstalked free-swimming zooids. Additionally, Epistylis spp. exerted much less predation stress on AnAOB than on nitrifying bacteria, and AnAOB tended to grow in aggregates in the interior of granules, thus favoring the growth and retention of AnAOB. Ultimately, the relative abundance of AnAOB reached up to a maximum of 8.2% in granules (doubling time of 9.9 d) compared to 1.1% in flocs (doubling time of 23.1 d), representing the most substantial disparity between granules and flocs. Overall, our findings advance the current understanding of interactions involved in granulation between protozoa and microbial communities and offer new insight into the specific enrichment of AnAOB under the novel granulation model.

Ciliated Peritrichous Protozoa in a Tezontle-Packed Sequencing Batch Reactor as Potential Indicators of Water Quality

The presence of colonial and solitary ciliated peritrichous protozoa was determined in a Sequencing Batch Reactor system filled with tezontle, a volcanic rock, economic, and abundant material that can be found in some parts of the world, like Mexico. The presence of these protozoa was related to the removal efficiencies of organic matter. Also, two novel staining techniques are proposed for staining both colonial and solitary peritrichous protozoa. The results show that tezontle promotes the growth of solitary and colonial ciliated peritrichous protozoa, which, once identified, could be used as indicators of the efficiency of the wastewater treatment process. Additionally, the staining techniques established in the current study allowed the precise observation of protozoan nuclei. They can represent a useful complementary methodology for identifying protozoan species present in water treatment processes, along with the already existing identification techniques. The number and variety of protozoa found in the system may be considered potential bioindicators of water quality during biological treatments.

State-of-the-Art Review on the Application of Membrane Bioreactors for Molecular Micro-Contaminant Removal from Aquatic Environment

In recent years, the emergence of disparate micro-contaminants in aquatic environments such as water/wastewater sources has eventuated in serious concerns about humans’ health all over the world. Membrane bioreactor (MBR) is considered a noteworthy membrane-based technology, and has been recently of great interest for the removal micro-contaminants. The prominent objective of this review paper is to provide a state-of-the-art review on the potential utilization of MBRs in the field of wastewater treatment and micro-contaminant removal from aquatic/non-aquatic environments. Moreover, the operational advantages of MBRs compared to other traditional technologies in removing disparate sorts of micro-contaminants are discussed to study the ways to increase the sustainability of a clean water supplement. Additionally, common types of micro-contaminants in water/wastewater sources are introduced and their potential detriments on humans’ well-being are presented to inform expert readers about the necessity of micro-contaminant removal. Eventually, operational challenges towards the industrial application of MBRs are presented and the authors discuss feasible future perspectives and suitable solutions to overcome these challenges.

Applicability of Using Biological Indices to Assess Water Quality of the Nile Branches, Egypt

<b>Background and Objective:</b> The Saprobity index (S) and the Wetland Zooplankton Index (WZI) are the most commonly used indices using zooplankton data to assess the water quality of many water bodies. However, these indices may be inadequate to assess the water quality of all freshwater bodies around the world. This study aims to evaluate the validity of these indices for assessing the water quality of the Nile branches (Damietta and Rosetta branches) as a case study. <b>Materials and Methods:</b> The validity of S and WZI is statistically tested against the Nile Chemical Pollution Index (NCPI) using linear regression analysis. The Physico-chemical parameters, zooplankton and Discriminant Analysis (DA) data show significant differences between the Damietta and Rosetta sites. <b>Results:</b> The results of both S and WZI do not coincide with those calculated with NCPI. The obtained S values show that all sites have poor water quality. On the other hand, the WZI values indicate that the Damietta branch sites in addition to the first two sites of the Rosetta branch (R<sub>1</sub> and R<sub>2</sub>) have moderate water quality, while the other sites have poor water quality. <b>Conclusion:</b> Finally, the NCPI results show that the Rosetta branch sites are heavily polluted, while the Damietta sites are clean. This study concludes that S and WZI inaccurately describe the ecological status of the study area.

Soil Microbial Biomass and Community Composition Relates to Poplar Genotypes and Environmental Conditions

Poplars, known for their diversity, are trees that can develop symbiotic relationships with several groups of microorganisms. The genetic diversity of poplars and different abiotic factors influence the properties of the soil and may shape microbial communities. Our study aimed to analyse the impact of poplar genotype on the biomass and community composition of the microbiome of four poplar genotypes grown under different soil conditions and soil depths. Of the three study sites, established in the mid-1990s, one was near a copper smelter, whereas the two others were situated in unpolluted regions, but were differentiated according to the physicochemical traits of the soil. The whole-cell fatty acid analysis was used to determine the biomass and proportions of gram-positive, gram-negative and actinobacteria, arbuscular fungi (AMF), other soil fungi, and protozoa in the whole microbial community in the soil. The results showed that the biomass of microorganisms and their contributions to the community of organisms in the soil close to poplar roots were determined by both factors: the tree-host genotype and the soil environment. However, each group of microorganisms was influenced by these factors to a different degree. In general, the site effect played the main role in shaping the microbial biomass (excluding actinobacteria), whereas tree genotype determined the proportions of the fungal and bacterial groups in the microbial communities and the proportion of AMF in the fungal community. Bacterial biomass was influenced more by site factors, whereas fungal biomass more by tree genotype. With increasing soil depth, a decrease in the biomass of all microorganisms was observed; however, the proportions of the different microorganisms within the soil profile were the result of interactions between the host genotype and soil conditions. Despite the predominant impact of soil conditions, our results showed the important role of poplar genotype in shaping microorganism communities in the soil.

Secondary effluent purification by a large-scale multi-stage surface-flow constructed wetland: A case study in northern China

Assessment of treatment performance in the large-scale constructed wetland (CW) for secondary effluent purification remains limited. The aim of this case study was to therefore to investigate the long-term treatment capacity of organics and ammonium pollutants in a large-scale multi-stage surface-flow (SF) CW fed with secondary effluents from the wastewater treatment plants (WWTPs) in northern China. The results for two-and-half-year study period indicated that the water quality parameters including chemical oxygen demand (COD) and ammonium (NH₄⁺-N) met the Chinese Grade III of Environmental Quality Standards. The mass reductions of COD and NH₄⁺-N were 53% (4032 kg ha^-1 y^-1) and 72% (511 kg ha^-1 y^-1), respectively. However, there was a significant positive correlation between influent loads and treatment performance. The optimal loading of 2.5 g m^-2 d^-1 for COD and 0.3 g m^-2 d^-1 for NH₄⁺-N could be recommended for designing the sustainable large-scale multi-stage SF CW wastewater treatments.