Effects of Temperature on the Characteristics of Nitrogen Removal and Microbial Community in Post Solid-Phase Denitrification Biofilter Process

Highlighting the importance of biodiversity conservation through the Holy Qur'an

Religious environmentalism relies upon religious texts and leadership to promote effective and long-lasting change for environmental problems, such as responsible use and conservation of natural resources and biodiversity. World religions note the importance of biodiversity and humanity's responsibility in stewarding biodiversity as a member of ecological communities. We reviewed Quranic verses that relate to biodiversity and align with United Nations Sustainable Development Goals (SDGs). The Holy Quran was reviewed in electronic and hard copy formats, and verses related to biodiversity were translated to English and tabulated by Qur'anic chapter, verse, and narrative citation. Twenty-one Qur'anic verses were identified that addressed biodiversity. Scriptures were divided into 5 groups that addressed provision of resources, governance or stewardship of resources, nature as a teacher, and human life in nature's communities or described creation of biodiversity. Qur'anic verses were aligned with 4 SDGs (goals 12-15), which address sustainable consumption of natural resources, global climate change, life in marine environments, and life in terrestrial environments, including freshwater ecosystems. This alignment demonstrates the interconnectedness of life, that conservation of biodiversity is referenced in the Quran, and how positive management of natural recourses can be beneficial to Muslim communities on local, national, and global scales. Positive movement toward ecofriendly practices, sound environmental resource use and management, biodiversity conservation, and governmental policies on conservation can be promoted through scriptures from the Holy Qur'an.

Seasonal characterization of the prokaryotic microbiota of full-scale anaerobic UASB reactors treating domestic sewage in southern Brazil

Upflow Anaerobic Sludge Blanket (UASB) reactors are alternatives in the anaerobic treatment of sanitary sewage in different parts of the world; however, in temperate environments, they are subject to strong seasonal influence. Understanding the dynamics of the microbial community in these systems is essential to propose operational alternatives, improve projects and increase the quality of treated effluents. In this study, for one year, high-performance sequencing, associated with bioinformatics tools for taxonomic annotation and functional prediction was used to characterize the microbial community present in the sludge of biodigesters on full-scale, treating domestic sewage at ambient temperature. Among the most representative phyla stood out Desulfobacterota (20.21-28.64%), Proteobacteria (7.48-24.90%), Bacteroidota (10.05-18.37%), Caldisericota (9.49-17.20%), and Halobacterota (3.23-6.55%). By performing a Canonical Correspondence Analysis (CCA), Methanolinea was correlated to the efficiency in removing Chemical Oxygen Demand (COD), Bacteroidetes_VadinHA17 to the production of volatile fatty acids (VFAs), and CI75cm.2.12 at temperature. On the other hand, Desulfovibrio, Spirochaetaceae_uncultured, Methanosaeta, Lentimicrobiaceae_unclassified, and ADurb.Bin063-1 were relevant in shaping the microbial community in a co-occurrence network. Diversity analyses showed greater richness and evenness for the colder seasons, possibly, due to the lesser influence of dominant taxa. Among the principal metabolic functions associated with the community, the metabolism of proteins and amino acids stood out (7.74-8.00%), and the genes related to the synthesis of VFAs presented higher relative abundance for the autumn and winter. Despite the differences in diversity and taxonomic composition, no significant changes were observed in the efficiency of the biodigesters.

Corpse decay of wild animals leads to the divergent succession of nrfA-type microbial communities

Animal carcasses introduce large amounts of nitrates and ammonium into the soil ecosystem. Some of this ammonium is transformed from nitrite through the nrfA-type microbial community. However, it is unclear how nrfA-type microorganisms respond to the decomposition of corpses. This study applied high-throughput sequencing to characterize the ecological succession of nrfA-type microbial communities in grassland soil. Our results showed that Cyclobacterium and Trueperella were the predominant genera for nrfA-type communities in soil with a decomposing corpse (experimental group), while Cyclobacterium and Archangium were dominant in soil without a corpse (control group). The alpha diversity indexes and the resistance and resilience indexes of the microbial communities initially increased and then decreased during decomposition. Compared with the control group, nrfA-encoding community structure in the experimental group gradually became divergent with succession and temporal turnover accelerated. Network analysis revealed that the microbial communities of the experimental group had more complex interactions than those of the control groups. Moreover, the bacterial community assembly in the experimental group was governed by stochastic processes, and the communities of the experimental group had a weaker dispersal capacity than those of the control group. Our results reveal the succession patterns of the nrfA-type microbial communities during degradation of wild animal corpses, which can offer references for demonstrating the ecological mechanism underlying the changes in the nrfA-type microbial community during carcass decay. KEY POINTS: • Corpse decay accelerates the temporal turnover of the nrfA-type community in soil. • Corpse decay changes the ecological succession of the nrfA-type community in soil. • Corpse decay leads to a complex co-occurrence pattern of the nrfA-type community in soil.

Enhancement of denitrification in biofilters by immobilized biochar under low-temperature stress

Efficient removal of nitrate under low temperature is challenging because of the reduction of the microbial activity. This study successfully explored the promotion on the performance of denitrification utilizing the immobilized biochar in biofilters under low temperature (6 ± 2 °C). The results showed that the immobilized biochar increased the denitrification rate by 76.8% and decreased the nitrous oxide emissions by 82.5%. Mechanistic studies revealed that the immobilized biochar increased the activities of the denitrifying enzymes and three enzymes involved in glycolysis. Furthermore, the immobilized biochar elevated the activity of the electron transport system by 31.8%. Finally, structural equation model explained that the increase of nitrate reductase activity was a crucial factor to enhance the total nitrogen removal efficiency in biofilters with immobilized biochar. Overall, the use of immobilized biochar can be a novel strategy to enhance nitrogen removal and reduce greenhouse gas emissions in biofilters under low temperature.

Effect of Hydraulic Retention Time on the Performance of a Compact Moving Bed Biofilm Reactor for Effluent Polishing of Treated Sewage

Treated effluent from a wastewater treatment plant can be further reused as a water resource for a water supply treatment plant. In this case, the treated sewage gathered in the study of the Class V National Water Quality Standard (NWQS) of Malaysia would be treated for use as a water resource for a water treatment plant. In a moving bed biofilm reactor (MBBR) with a 500-L working volume, organic pollutants, undesirable nutrients, and bacteria were removed without disinfectant. At 24-h hydraulic retention time (HRT), the maximum removal efficiency of 5-day biological oxygen demand, ammonia–nitrogen (NH3-N), and total phosphorus were 71%, 48%, and 12%, respectively. The biofilm thickness, which was captured using scanning electron microscopy, increased from 102.6 μm (24-h HRT) to 297.1 μm (2-h HRT). A metagenomic analysis using 16S rRNA showed an abundance of anaerobic bacteria, especially from the Proteobacteria phylum, which made up almost 53% of the total microbes. MBBR operated at 24-h HRT could improve effluent quality, as its characteristics fell into Class IIA of the NWQS of Malaysia, with the exception of the NH3-N content, which indicated that the effluent needed conventional treatment prior to being reused as potable water.

Study on performance and mechanism of enhanced low-concentration ammonia nitrogen removal from low-temperature wastewater by iron-loaded biological activated carbon filter

In order to strengthen the treatment of low-concentration ammonia nitrogen wastewater at low temperature, iron-loaded activated carbon (Fe-AC) with ultrasonic impregnation method was used as the filter material of biofilter process. The performance and mechanism of ammonia nitrogen removal from simulated secondary wastewater by iron-loaded biological activated carbon filter (Fe-BACF) were studied at 10 °C. The characterization results showed that iron was loaded on the surface of AC in the form of Fe₂O₃, and the specific surface area, total pore volume, pore size and alkaline functional group content of Fe-AC were obviously increased. After the formation of biofilm on the surface of filter media, the average removal rate of ammonia nitrogen by Fe-BACF (97.9%) was significantly higher than that of conventional BACF (87.8%). The improved surface properties increased the number and metabolic activity of microorganisms, and promoted the secretion of EPS on the surface of Fe-BAC. The results of high-throughput sequencing showed that the existence of Fe optimized the bacterial community structure on the surface of Fe-BAC, with the increase of the abundances of psychrophilic bacteria and ammonia nitrogen removal bacteria. The mechanism of enhanced ammonia nitrogen removal by Fe-BACF was the joint action of many factors, among which the main causal relationship was that modification of iron could optimize the number and category of microorganisms on Fe-BAC surface by improving the surface properties, thus improving the biological nitrogen removal ability. Results of this study provided a practical way for the treatment of low ammonia nitrogen wastewater in cold regions.

Shifting from Conventional to Organic Filter Media in Wastewater Biofiltration Treatment: A Review

Biofiltration is a promising wastewater treatment green technology employed to remove various types of pollutants. The efficiency of biofiltration relies on biofilm, and its performance is significantly influenced by various factors such as dissolved oxygen concentration, organic loading rate, hydraulic retention time, temperature, and filter media selection. The existing biofilters utilize conventional media such as gravel, sand, anthracite, and many other composite materials. The material cost of these conventional filter materials is usually higher compared to using organic waste materials as the filter media. However, the utilization of organic materials as biofilter media has not been fully explored and their potential in terms of physicochemical properties to promote biofilm growth is lacking in the literature. Therefore, this review critically discusses the potential of shifting conventional filter media to that of organic in biofiltration wastewater treatment, focusing on filtration efficiency-influenced factors, their comparative filtration performance, advantages, and disadvantages, as well as challenges and prospective areas of organic biofilter development.

Temperature-induced difference in microbial characterizations accounts for the fluctuation of sequencing batch biofilm reactor performance

Generally, the purification performance of bioreactors could be influenced by temperature variation via shaping different microbial communities. However, the underlying mechanisms remain largely unknown. Here, the variation trends of microbial communities in three sequencing batch biofilm reactors (SBBRs) under four different temperatures (15, 20, 25, 30 °C) were compared. It was found that temperature increment led to an obvious enhancement in nutrient removal which was mainly occurred in the aerobic section. Meanwhile, distinct differences in dominant microbial communities or autotrophic nitrifiers were also observed. The performance of the SBBR reactors was closely associated with nitrifier communities since the treated wastewater was characterized by a severe lack of carbon sources (mean effluent COD ≤ 14.4 mg/L). Spearman correlation unraveled that: most of the differentiated microbes as well as the dominant potential functions were strongly associated with nutrient removal, indicating the temperature-induced difference in microbial community well explained the distinction in purification performance.

Evaluating the effect of seasonal temperature changes on the efficiency of a rhizofiltration system in nitrogen removal from urban runoff

The study presents an evaluation of nitrogen removal efficiency of a pilot-scale rhizofiltration system in Pretoria, South Africa. The rhizofiltration system was divided into two sections, one side planted with common reeds (Phragmites australis) and the other side was without plants kept as a control. The objective of the study was to evaluate the influence of seasonal temperature on the removal of nitrogen species from the simulated urban runoff using the rhizofiltration system. The final effluent from the filter was collected bimonthly at different sampling points for 10 months after an application time of 5 min and 25 min. Duplicate samples were taken to determine the concentrations of TKN (Total Kjeldahl nitrogen), ammonium, nitrate and chemical oxygen demand (COD) for the raw influent and final effluent from the rhizofiltration system. Temperature and pH were determined on-site. During the monitoring period, there was no significant difference in the inflow concentration of ammonium in colder and warmer months for both planted and control sides. Furthermore, the composition of the feed medium to the rhizofilter was kept the same in both cold and warm season and for both planted and control sides. The removal of ammonium in colder and warmer months was not significant in both systems. At an average temperature increase of 5.2 °C in the warmer months, the ammonium removal efficiency in the planted side increased by 7.5%, while for the control side the removal efficiency increased by 2.4%. The difference in removal was not significant between the averages of effluent ammonium after an application time of 25 min in colder versus warmer months for the planted and control sides of the system. Furthermore, an increased nitrification rate was more evident in the planted than in the control side, which was subsequently denitrified. It was observed that 60.4% of nitrate concentration was potentially removed in the planted side whereas 45.4% was potentially denitrified in the control side. These results suggest positive correlation between nitrate concentration and the potential for denitrification. The nitrate removal efficiency dropped to 32.2% for the planted site and to 26.1% for the control system in colder months. Temperature had an effect on nitrogen removal, since nitrogen removal efficiency decreased in colder months. Complete nitrogen removal could not be achieved under the operating conditions.

Effects on soil microbial community after exposure to neonicotinoid insecticides thiamethoxam and dinotefuran

The wide application of neonicotinoid insecticides in soil may affect soil microbial community, yet the information is limited. This study first reports the effects of thiamethoxam and dinotefuranon on soil microbial community. Soil from a forest land was collected and spiked with different nominal levels (0.02 mg kg^-1, 0.2 mg kg^-1 and 2.0 mg kg^-1) of thiamethoxam and dinotefuran, respectively, and cultivated for 112 days. During the study, concentrations of the two neonicotinoids and their potential degradation products were monitored by LC-MS/MS. At day 112, the soils were analyzed for genetic profile by high-throughput sequencing and carbon metabolic profile by Biolog-ECO plate. The results showed that thiamethoxam and dinotefuran were both attenuated during the study with rate constants being 0.008-0.017 d^-1 and 0.024-0.032 d^-1, respectively, and biodegradation played an important role. As compared to the blank control, the exposure to the studied two neonicotinoids changed the microbial community, and the changes were influenced by both the type of neonicotinoid and the level of exposure. As compared to the blank control, the relative abundances of phyla Gemmatimonadetes and OD1 decreased under most exposed conditions, while the relative abundances of Chloroflexi and Nitrospirae increased under most exposed conditions. The community transition changed the functional potential, particularly carbon metabolism (mostly decreased) and nitrogen metabolism (mostly increased). As compared to the blank control, the utilization of total 31 carbon sources (including six categories) was increased under low exposure to thiamethoxam, but was decreased under all other exposed conditions. Low exposure to dinotefuran stimulated the utilization of three categories of carbon sources (amines, carbohydrates and phenolic compounds). Low exposure to both neonicotinoids increased the community diversity, while middle and high exposure to both neonicotinoids decreased the community diversity. These findings provide new insights into the effects of neonicotinoids on microbial community in soil.