The single-stage partial nitritation–anammox (PN/A) process is severely limited by a long start-up time and unstable removal efficiency. In this study, PN/A was developed in 67 days in a novel packed bed equipped with porous bio-carriers by gradually increasing the influent nitrogen loading rate (0.15–0.73 kg-N m⁻³·d⁻¹) and controlling the dissolved oxygen (< 1.2 mg L⁻¹). An average ammonium nitrogen removal efficiency (ARE) and total nitrogen removal efficiency (TNR) of 87.01 and 72.41%, respectively, were obtained. This represents a reliable alternative method of achieving rapid PN/A start-up. The results of 16S rRNA sequencing showed that Proteobacteria and Planctomycetes, with which ammonia-oxidizing bacteria and anammox bacteria were affiliated, accounted for 38.8%, representing the dominant phylum in the system after acclimation. The abundance of Nitrosomonas and Candidatus Brocadia increased by 16 and 1.79%, respectively. The results of metagenomics and metatranscriptomics revealed that the nitrite oxidation process was blocked by the transcriptional suppression of nitrite oxidoreductase and the entire nitrogen metabolism process was dominated by the partial nitritation and anammox process. Moreover, a high abundance of heterotrophic bacteria with potential for nitrogen removal was detected. In the nitrogen cycle, a widespread nitrite-accumulated denitrification helps to form a nitrite loop, which promotes the efficiency of total nitrogen removal. This is crucial for further improving the nitrogen removal mechanism in the PN/A system.

Animal manures contain bacteria which may be used to indicate the potential microbial pollution of irrigation and recreation water sources. The objective of this work was to research how the release of these indicators to runoff is affected by the concurrent influence of the manure consistency and the duration of manure weathering between rainfall events. Liquid and solid dairy manure was applied on grassed soil boxes. The percentage of manure-borne bacteria removed in runoff over 1 hour was determined after the initial rainfall immediately after manure application and after rainfalls that occurred 1 week and 2 weeks after the initial rainfall. The runoff delay was linearly related to the time between rainfalls and was significantly affected by both weathering duration and manure consistency (P = 0.017 and 0.038, respectively). The runoff delay was dependent on the antecedent gravimetric soil water content (R² = 0.92 and 0.99 for liquid and solid manure treatments, respectively). Manure weathering caused a substantial decrease in the removal of fecal bacteria with runoff in the 2-week weathering compared with the 1-week weathering treatments for both of E. coli and enterococci (P = 0.063 and 0.049, respectively). Every day of weathering decreased the percentage of the released E. coli and enterococci by about 1.2 and 1.5 times, respectively, for both manure consistencies. Manure consistency was not found to significantly affect the percentages of E. coli or enterococci removed with runoff for any level of weathering. Results indicate the need of correcting existing manure bacteria removal models by accounting for manure consistency and weathering duration.

We have modelled the possible antibiotics concentrations at different nodes along the Volga River using a system dynamics model developed for the purpose. The antibiotics concentrations in the river estimated using the model are far above the proposed no effect concentrations (PNEC) limits suggested by the WHO and EU European Environmental Agency at 0.1 μg/l total antibiotics water content. Concentrations in the range of 0.1 to more than 4 μg/l have been simulated with the model. A part of this comes from use in the agricultural sector. The simulations were done with a system dynamics model built for the purpose. The Volga model simulations are uncertain because of lack of measurements in the river and lack of accurate estimates of antibiotics loads from medical and agricultural use. The picture is consistent with observations in earlier international studies from various rivers in the world. To comply with the suggested PNEC limit, the medical pollution to Volga needs to be reduced by 90%.

Climate warming greatly affects the frequency and intensity of flash droughts, which can cause huge damage to agriculture. It is important to understand the changing rules of future flash droughts and take precautionary measures in advance. Thus, we focused on the flash drought characteristic of the Jinghe River basin using variable infiltration capacity (VIC) model and four-model ensemble in the two representative concentration pathway scenarios. Four-model ensemble mean can well capture hydrological changes in the reference period. The heat wave flash drought (HWFD) and the precipitation deficit flash drought (PDFD) mainly occur in the northern during reference period. The HWFD and PDFD have shown a linear growth trend in the future and both shown higher growth rates in the RCP8.5 scenario. The frequency of occurrence (FOC) increments of flash droughts were relatively high in the southern Jinghe River basin. And the HWFD and the PDFD mainly occurred in May–September. Further results indicate that the contribution of the maximum temperature to HWFD was the biggest (greater than 0.7), followed by evapotranspiration (ET) and soil moisture (SM). The contribution of maximum temperature to PDFD was the biggest (greater than 0.5), followed by precipitation and ET. Global warming in the twenty-first century is likely to lead to intensification of flash droughts. Therefore, measures and suggestions were proposed to effectively respond to flash droughts in our study.

This study assessed the bacterial populations in a non-sanitary landfill around Guarani Aquifer recharge zone in Brazil. Samples from two different positions (sites 1 and 2) at three different depths were evaluated, totaling six solid waste samples; two samples from an impacted stream were also collected. 16S rRNA sequencing was performed using the Ion S5TM XL platform; 3113 operational taxonomic units (OTUs) and 52 phyla were identified. Proteobacteria (37%) and Firmicutes (28%) were the most abundant phyla in the landfill, whereas Proteobacteria (~ 50%) and Bacteroidetes (~ 10%) were more profuse in surface water samples. Canonical correlation analysis (CCA) enabled us to clearly separate the samples according to their spatial location (site 1 or 2) or environmental matrix (surface water or solid waste samples), showing that microbiological populations are strongly associated with site-specific conditions and the kind of environmental matrix they come from. Environmental factors that mostly influenced the microbial communities were organic matter, oxidation–reduction potential, moisture, alkalinity, nitrogen (TKN), sodium, potassium, and zinc. Exiguobacterium (phylum Firmicutes) was overwhelmingly dominant at site 1 and was associated with higher concentrations of organic matter and potassium. Differently, site 2 did not present such dominant genera and was more diverse having lower concentrations of organic matter and nutrients. Distinct environments co-exist inside the same waste deposit, including zones which are representative of active and closed landfills and the occurrence of considerable physicochemical and microbiological shifts within short distances. Those shifts indicate that microbial populations are well adapted to the heterogeneity typical of urban solid waste, which is possibly beneficial to contaminant degradation. Graphical abstract

Anthropogenic activities such as industrial, mining, or agricultural are the main sources of environmental contamination. One of the most problematic contaminations concerns metals and metalloids from mining activities. This contamination raises the question of the environmental risk induced and the spread of this pollution (geographical and trophic) and the associated health risk. The integrated, multi-analytical approach of this study conducted on the mining district of Cartagena-La Union (Murcia, Spain) as part of the Interreg SUDOE European project “Soil Take Care” aims to (i) precisely define the speciation of contaminants of interest (Zn, Pb, Cd, As), (ii) predict the environmental risk related to storage stability, and (iii) establish the link between the speciation of the bearing phases and the associated health risk. To do this, a representative zone in the Cartagena-La Union mining district close to the populations was chosen. A physic-chemical characterization of the samples was performed (pH, electrical conductivity, CEC, and total metal(loid) concentrations), and the mineralogy was determined using XRD and SEM-EDS. The environmental risk was highlighted from sequential BCR-type extractions and EN-12457 leaching tests. Finally, the health risk was defined using the PSF inhalation bioaccessibility test and UBM bioaccessibility protocol (based on an operational chemical methodology mimicking soil ingestion and its residence in the gastrointestinal tract of the human body). These analyses revealed 2 groups of samples with distinct behavior. The first group of samples presents relatively stable bearing phases, mainly found in the residual fraction (As and Pb), presenting only a low health risk (very low bioaccessible). The second group consists of Cd and/or Zn-bearing phases, mainly labile (resulting from dissolution/precipitation phenomena), while gastric bioaccessibility reaches more than 85%. Note that Pb, Cd, and Zn have the potential to cause non-carcinogenic risks to children and As and Pb present a carcinogenic risk for children and adults even if only the bioaccessible fraction is considered. It has therefore been shown that the meteoric alteration of the tailing induces a change in speciation leads to an increase in environmental and health risks. These results are essential because they highlight the need for an integrated approach in order to clearly highlight the presence of risks but also that this approach will allow a better understanding of the potential rehabilitation path of this site.

Nutrients that fall on the ground from the atmosphere represent a minor component of the total nitrogen (N) input to soils, especially when compared with agricultural, civil and industrial inputs (i.e. sewage treatment plants or sewage systems, fertilizer and manure applications). However, integrating all nitrogen forms, processes and scales can represent a breakthrough challenge for the understanding and the management of the N cycle. A monitoring experiment was set up to collect wet atmospheric depositions in a human-impacted area with multiple land uses, representing different emission sources. Rainwater collection was executed in the surroundings of Milan, in northern Italy, starting from February 2017 to February 2019. The presence of N compounds and their temporal variations in rainwater are consistent with pollution coming from local anthropogenic emission sources of nitrogen oxides and ammonia, mainly related to the use of the heating systems in the cold seasons and the spreading of fertilizers and manure on agricultural fields. Consequently, the total amount of N wet depositions ranges between 14 and about 30 kg/ha yr in the study area. As leaching of N compounds from soils generally increases at deposition rates higher than about 10 kg(N)/ha yr, this work suggests that the N atmospheric input to soils could not be neglected when evaluating the impacts of N sources to terrestrial and aquatic ecosystems, as well as to groundwater resources. This highlights the need of wisely integrating air, soil and water policies for minimising the risk to deteriorate surficial ecosystems and groundwater.

The ability of locally laboratory-synthesized polyaluminium chloride (PAC) with high Al₁₃ content (PAC-Al₁₃) to remove organic, inorganic matter and colour from potable water, agricultural and electroplating wastewaters was evaluated relative to commercial PAC (PACI). PAC-Al₁₃ used in this study was prepared using batch titration of NaOH into AlCl₃·6H₂O solution under vigorous stirring as opposed to the conventional slow-base titration method. The highly pure PAC-Al₁₃ (containing 79% polymeric Al₁₃ species) with high basicity (87%) was isolated and extracted using the sulphate displacement method and metathesis reaction. PAC-Al₁₃ showed higher COD (85–96%), metals (95–100%), TDS (86–90%) and colour (90–95%) removal compared with PACI, i.e. COD (57–74%), metals (71–99%), TDS (58–80%) and colour (85–92%). The dominance of polymeric Al₁₃ species in PAC-Al₁₃ was supported from the scanning electron microscopy images (presence of Keggin structure of Al₁₃) and the ²⁷Al nuclear magnetic resonance analysis that showed the appearance of a single peak at 62.1 ppm. This study demonstrated the potential of using a new type of PAC, produced using simple preparation technique and contain high polymeric Al₁₃ species, that has the ability to remove contaminants from water and wastewater systems more efficiently.

The degradation of diclofenac sodium (DCF) in pre-magnetization Fe⁰/persulfate (Pre-Fe⁰/PS) and Fe⁰/PS systems were studied in detail in this study. The influencing operational conditions (initial PS dosage, Fe⁰ dosage, and pH) were studied for their effects on the DCF degradation. The removal rate constant for DCF by the Pre-Fe⁰/PS system was 2.1–6.2 times higher than that of the Fe⁰/PS system. A higher TOC removal efficiency (81.5%) was observed during the mineralization of DCF in the Pre-Fe⁰/PS process than that of the Fe⁰/PS process (70%). The results of electron paramagnetic resonance (EPR) confirmed that the Pre-Fe⁰/PS system could produce much more •OH and SO₄⁻• at a faster rate than the Fe⁰/PS system. Moreover, the degradation mechanism of DCF by the Pre-Fe⁰/PS process was elucidated. This work would provide a perspective on the Pre-Fe⁰/PS process for efficient degradation of DCF, exhibiting advantages to removing DCF, such as broaden the range of working pH and reduce the amount of chemicals. So, it is an efficient and potential method to remove DCF from wastewater by the Pre-Fe⁰/PS process.

Heavy metal contamination from landfills has become a worldwide problem. Concerns have been raised over their impacts on human health and the environment. Soil amendment-assisted phytoremediation is rapidly gaining attention as a biotechnology to accelerate heavy metal (HM) removal from contaminated soils or immobilize the HMs. How different amendments influence this process is still an important research question. This study quantified the bioaccumulation factor (BAF) and removal efficiency (RE) of HMs by wheat (Triticum aestivum), bean (Vicia faba), and rocca (Eruca sativa) in a pot experiment with biochar (BC), humic substances (HS) (in the form of potassium humate), and iron oxide (FO) amendments to clarify the effect of these treatments on phytoremediation. Each amendment was applied to the soil at a rate of 20 g kg⁻¹ soil, with unamended soil as a control. The results indicated that the available HMs were significantly decreased in the amended soils (p < 0.05) as compared with untreated soil. Plant concentrations of all the studied metals decreased with the soil amendments as compared to untreated soils. BAF was higher than 1 in all plants, and RE indicated the plants were most efficient in removing Pb from the studied soils. In general, soil amendments aided soil HM immobilization and reduced the accumulation of HMs in the cultivated plants. The studied amendments could be further explored as tools to remediate contaminated sites.