Diversity and distribution of bacteria in a multistage surface flow constructed wetland to treat swine wastewater in sediments

A review: Marine aquaculture impacts marine microbial communities

Marine aquaculture is key for protein production but disrupts marine ecosystems by releasing excess feed and pharmaceuticals, thus affecting marine microbes. Though vital, its environmental impact often remains overlooked. This article delves into mariculture's effects on marine microbes, including bacteria, fungi, viruses, and antibiotic-resistance genes in seawater and sediments. It highlights how different mariculture practices-open, pond, and cage culture-affect these microbial communities. Mariculture's release of nutrients, antibiotics, and heavy metals alters the microbial composition, diversity, and functions. Integrated multi-trophic aquaculture, a promising sustainable approach, is still developing and needs refinement. A deep understanding of mariculture's impact on microbial ecosystems is crucial to minimize pollution and foster sustainable practices, paving the way for the industry's sustainable advancement.

Comparative study on the treatment of swine wastewater by VFCW-MFC and VFCW: Pollutants removal, electricity generation, microorganism community

Swine wastewater, characterized by high organic and nutrient content, poses significant environmental challenges. This study aims to compare the effectiveness of two treatment technologies, namely Vertical Flow Constructed Wetland-Microbial Fuel Cell (VFCW-MFC) and Vertical Flow Constructed Wetland (VFCW), in terms of pollutant removal, electricity generation, and microorganism community dynamics. The results showed that the average removal efficiencies of chemical oxygen demand (COD), ammonia nitrogen, total nitrogen (TN), total phosphorus (TP) and sulfadiazine antibiotics (SDZ) by VFCW-MFC were as high as 94.15%, 95.01%, 42.24%, 97.16% and 82.88%, respectively, which were all higher than that by VFCW. Both VFCW-MFC and VFCW have good tolerance to SDZ. In addition, VFCW-MFC has excellent electrical performance, with output voltage, power density, coulombic efficiency and net energy recovery up to 443.59 mV, 51.2 mW/m³, 52.91% and 2.04 W/(g·s), respectively, during stable operation. Moreover, the microbial community diversity of VFCW-MFC was more abundant, and the species abundance distribution in cathode region was more rich and even than in anode region. At phylum level, the dominant microorganisms in VFCW-MFC included Proteobacteria, Bacteroidota, Firmicutes and Actinobacteriota, which showed good degradation effect on SDZ. Proteobacteria and Firmicutes are also involved in electricity production. Chloroflexi, Proteobacteria and Bacteroidota play a major role in nitrogen reduction.

Removing chemical and biological pollutants from swine wastewater through constructed wetlands aiming reclaimed water reuse

Reusing reclaimed wastewater is needed to fight water scarcity, reduce freshwater consumption and conserve water resources, but one must ensure that hazardous substances are fully removed/eliminate before that reuse. The potential of lab-scale constructed wetlands (CWs) for the removal of chemical and biological contaminants from livestock wastewater, while maintaining nutrient levels for fertilization, was assessed, evaluating changes in microbial communities, with particular focus on potential pathogens. CW microcosms with two different substrates (lava rock or light expanded clay aggregate), both planted with Phragmites australis, were tested. After 15 days of treatment, removal rates were higher than 80% for Cd, Cr, Cu, Fe, Pb and Zn, in general with no significant differences between the two different substrates. Organic matter and nutrients were also removed but their levels still allowed the used of the treated wastewater as a fertilizer Removal of bacterial contamination was estimated through enumeration of cultivable bacteria. High removal rates of fecal indicator bacteria were observed, reaching >95% for enterococci and >98% for enterobacteria after 15 days of treatment, decreasing hazardous biological contaminants initially present in the wastewater. In addition, the microbial communities in the initial and treated wastewater, and in the plant roots bed substrate, were characterized by using 16SrRNA gene amplicon sequencing. Microbial communities in the CW systems showed a clear shift comparatively with the initial wastewater showing system adaptation and removal potentialities. This also revealed an important removal of the most represented potential pathogenic genus, Clostridium, which relative abundance decreased from 33% to 1% through the treatment. Overall, CWs showed potential to be efficient in removing chemical and biological contaminants, while maintaining moderated levels of nutrients, allowing the reuse of reclaimed water in agriculture, namely as fertilizer. Current results will contribute for the optimization and use of CWs for a sustainable treatment of liquid wastes, promoting the circular economy.

Effect of LDPE and biodegradable PBAT primary microplastics on bacterial community after four months of soil incubation

Biodegradable plastics would be gradually degraded by microbes after being used and discarded, forming biodegradable microplastics (BMPs). It is however not clear if it, like conventional microplastics, can affect the original soil ecological balance. In this study, the non-degradable LDPE (low density polyethylene) was used as the reference primary microplastic, and the BMP PBAT (polyadipate/butylene terephthalate) was used as the test object. The effects of the amount of PBAT on soil physical-chemical properties, bacterial community were investigated using high throughput sequencing. The results showed that when the highest amount of PBAT applied was up to 250 times higher than the normal application amount, resulted in a certain dose-effect, and a higher amount of PBAT would reduce the content of NO₃^--N and TP. The lower amount of PBAT relatively increased the diversity of soil bacterial communities, and the relative abundance of the unique Azotobacter increased with increasing PBAT amount. The abundance of bacterial community in soil with different PBAT amounts was significantly correlated with the soil's physical-chemical properties. In addition, Mesorhizobium, TM7a and Azotobacter were observed to be highly tolerant bacteria in PBAT containing soil which can be actively explored to study the biodegradation of BMPs PBAT.

Long-term performance of nutrient removal in an integrated constructed wetland

Constructed wetlands (CWs) have been regarded as efficient technologies for both wastewater treatment and reuse of water resources. Most studies on CW treatment efficiency are limited to a short-term perspective, and there are still many unknowns about the long-term performance of CWs. Here we evaluated the performance of an integrated CW that has been in operation for more than ten years. The average removal rates of TN and TP were maintained at 53.6% and 67.3% over 10 years, respectively. The annual mass reductions in TN and TP reached 937.5 kg ha^-1 yr^-1 and 303.2 kg ha^-1 yr^-1, respectively. In addition, TN removal rate was significantly higher in summer and autumn than those in spring, yet there was no seasonal difference in TP removal. The bacterial richness and diversity in summer and autumn were higher than those in spring. TN and TOC not only determine the bacterial community structure, but also affect the removal efficiency of CW. Denitrification and dephosphorization microorganisms were enriched and accounted for a considerable proportion (21.14-52.85%) in the bacterial community. In addition, the relative abundance of Pseudomonas was significantly positively related with the rate of TN and TP removal.

Bacterial community response to different nitrogen gradients of swine wastewater in surface flow constructed wetlands

How sediment bacterial community structure and diversity responds to different gradients of nitrogen (N) in swine wastewater is poorly understood. Here, the effects of different total nitrogen (TN) concentrations in swine wastewater on the microbial diversity and community composition in surface flow constructed wetlands (SFCWs) were investigated. The five concentration gradients included 2, 250, 300, 350, and 400 mg L^-1. Under high N concentrations (>300 mg L^-1), the Ace and Chao1 indexes increased, however, the Shannon index declined with increasing N concentration. The relative abundance of Chloroflexi, Acidobacteria and Actinobacteria showed an increasing trend. In contrast, under relatively low N concentrations (≤300 mg L^-1), Shannon index increased with increasing N concentration. The relative abundance of Bacteroidetes and Verrucomicrobia exhibited an increasing trend with increasing N concentration. TN, NH₄⁺ and NO₃^- significantly influenced on the microbial community distribution and composition (P < 0.05). These findings provide evidence that N concentration of swine wastewater is powerful predictor of bacterial diversity and community composition in SFCWs.

Improvement of Black-Odor Water by Pichia Strain GW1 under Optimized NH3-N Degradation Conditions

In this study, a yeast strain with an outstanding NH₃-N degradation ability was isolated from the sediment of a black-odor water channel in Guangdong Province, China. Based on phenotypic and phylogenetic analysis, this strain was identified as Pichia kudriavzevii GW1. The optimum conditions for NH₃-N degradation by the GW1 strain were as follows: 0.3% inoculum concentration, 1.5 L/min aeration, pH 7, and a temperature of 35°C. Under optimized conditions, the GW1 strain degraded 95.5% of the NH₃-N. The strain was then added to simulated black-odor water under optimal degradation conditions to investigate changes to the bacterial community over time. 16S rRNA sequencing of samples collected on days 0, 7, 14, and 21 showed that, in the presence of the GW1 strain, the relative abundances of the phyla Proteobacteria, Bacteroidetes, Chloroflexi, and Firmicutes increased in the black-odor water. In addition, the relative abundance of Propionivibrio, a known NH₃-N degrading genus, increased. This study will facilitate the use of microbiological methods to repair black-odor water.

Can Constructed Wetlands be Wildlife Refuges? A Review of Their Potential Biodiversity Conservation Value

The degradation of wetland ecosystems is currently recognized as one of the main threats to global biodiversity. As a means of compensation, constructed wetlands (CWs), which are built to treat agricultural runoff and municipal wastewater, have become important for maintaining biodiversity. Here, we review studies on the relationships between CWs and their associated biodiversity published over the past three decades. In doing so, we provide an overview of how wildlife utilizes CWs, and the effects of biodiversity on pollutant transformation and removal. Beyond their primary aim (to purify various kinds of wastewater), CWs provide sub-optimal habitat for many species and, in turn, their purification function can be strongly influenced by the biodiversity that they support. However, there are some difficulties when using CWs to conserve biodiversity because some key characteristics of these engineered ecosystems vary from natural wetlands, including some fundamental ecological processes. Without proper management intervention, these features of CWs can promote biological invasion, as well as form an ‘ecological trap’ for native species. Management options, such as basin-wide integrative management and building in more natural wetland components, can partially offset these adverse impacts. Overall, the awareness of managers and the public regarding the potential value of CWs in biodiversity conservation remains superficial. More in-depth research, especially on how to balance different stakeholder values between wastewater managers and conservationists, is now required.

Co-cultivation of Rhodotorula glutinis and Chlorella pyrenoidosa to improve nutrient removal and protein content by their synergistic relationship

With the continuous development of the livestock breeding industry, the amount of piggery wastewater discharged increases year by year, and the pressure of controlling environmental pollution continuously increases. A novel method using a co-culture of Chlorella pyrenoidosa and Rhodotorula glutinis in piggery wastewater was proposed in this study, which was aimed at treating piggery wastewater and producing useful products. The results showed that the optimal inoculum ratio of algae to yeast was 3 : 1 in the wastewater, which achieved the removal efficiencies of 58.53%, 36.07%, 33.20% and 56.25% for ammoniacal nitrogen (NH₃-N), total nitrogen (TN), total protein (TP) and chemical oxygen demand (COD), respectively, after 6 d. The synergistic relationship of C. pyrenoidosa and R. glutinis was preliminarily validated using the oxygen/carbon dioxide exchange balance and scanning electron microscopy images. The co-cultivation system gained 59.8% (w/w) protein within 5 d which can be used as a feed additive, and produces aquatic animals with better growth and quality. Thus, the 1000 litre pilot scale bioreactor was used indoors and removed 82.65% of TN, 53.51% of TP, 93.48% of NH₃-N and 85.44% of COD in 21 d which gave a better performance for TN (p < 0.05) than the bench scale results. This system improves the nutrition removal and protein production efficiencies, and is a promising method for piggery wastewater treatment and the pig breeding industry.

Aiming at treating piggery wastewater and producing useful products, a novel method using a co-culture of Chlorella pyrenoidosa and Rhodotorula glutinis in piggery wastewater was proposed in this study to improve nutrient removal and the protein content in the feed produced.