Humic substances sorption from wastewater on the biochar produced from the waste materials.

In recent years, increasing attention has been paid to the possibility of converting waste materials, e.g. manure, bio-waste, green waste, waste from the water and sewage industries (e.g. post-fermentation sludge), and agri-food waste into biochars (BCs) by pyrolysis. The ability of biochar to improve soil health and fertility is driving growing interest in its use as a soil amendment. A high soil stability of BCs and their excellent nutrient sorption properties are the main reasons for the superiority of such materials over other organic soil amendments. In addition, BCs can retain soil-relevant compounds, including humic substances (HSs). Since most of the resources used to produce humic fertilisers are non-renewable, the effluent from anaerobic digestion of sewage sludge (reject water, RW), which contains high levels of HSs, is considered a promising target for their recovery. In this study, the potential of ten BCs derived from pine, oak, straw, sunflower, and digestate at different pyrolysis temperatures for the recovery of HSs from RW was evaluated. The sorption of HSs on the applied BCs was conducted using contact method for 24 h and then determined spectrophotometrically. The most effective sorbents for HSs from RW were BCs obtained from straw in the low and high temperatures with the sorption capacity of 3.10 mg g-1 and 5.31 mg g-1, respectively. It was observed that the BCs produced from the same biomass at different pyrolysis temperatures had different sorption capacities for FA, HA, and a mixture of these compounds. The results indicated that BCs obtained from sunflower at different temperatures and oak at high temperature were the most promising sorbents for the recovery of HSs from RW. Such materials have the potential to be applied to soil and were selected for further evaluation due to their ability to enhance soil quality and immobilize pollutants. Further studies will assess their effectiveness in different soil conditions, their stability and persistence, and their impact on plant health and growth.

Soil application potential of post-sorbents produced by co-sorption of humic substances and nutrients from sludge anaerobic digestion reject water.

This study introduces a novel soil conditioning approach using humic substances (HSs) and nutrients co-recovered from reject water from sewage sludge anaerobic digestion. For the first time, HSs and nutrients were simultaneously recovered through sorption on low-cost, environmentally inert materials: natural rock opoka (OP) and waste autoclaved aerated concrete (WAAC). This innovative application of OP and WAAC as carriers and delivery agents for soil-relevant substances offers potential for resource recovery and soil conditioning. Results indicate that the post-sorption opoka (PS-OP) and post-sorption waste autoclaved aerated concrete (PS-WAAC) effectively release retained HSs at 350-480 µg g⁻1 d⁻1, respectively. These materials also show potential as NPK fertilizers, releasing 280-430 µg g⁻1 d⁻1 N-NH4⁺, 80-150 µg g⁻1 d⁻1 P-PO4³â», and 270-350 µg g⁻1 d⁻1 K⁺. Additionally, PS-OP demonstrated promising fungicide properties, reducing P. diachenii growth by 31% at a concentration of 1 g L⁻1. A two-way ANOVA indicated that the effects of PS-OP and PS-WAAC on soil physicochemical and biological parameters varied with plant species. Both post-sorbents improved the quality of soil collected from sand mining area, increasing cation exchange capacity by 7%-85% and organic matter content by 10%-58%. They also enhanced the functional potential of soil microbial communities, increasing their metabolic activities by 23%-36% in soils sown with clover and by 33%-39% in soils sown with rapeseed. An opposite effect was observed in soils sown with sorghum, suggesting these amendments may not universally act as plant biostimulants. The effectiveness of these post-sorbents in enhancing plant growth varied depending on plant species and the mineral base of the post-sorbent. PS-OP increased the total length of clover and sorghum by 41% and 36%, and their fresh biomass by 82% and 80%, respectively. In turn, PS-WAAC increased the total length of clover and sorghum by 76% and 17%, and their fresh biomass by 29% and 15%, respectively. It was notably more effective than PS-OP for rapeseed. This study proposes a strategy to decrease reliance on non-renewable resources and costly sorbents while minimizing environmental impact. It shows that PS-OP and PS-WAAC can enhance soil quality, microbial activity, and plant growth. Given their origins, these amendments are recommended for soil remediation, particularly in degraded areas. Future research should focus on optimizing their application across various plant species to maximize effectiveness.

Current challenges and future perspectives for the full circular economy of water in European countries.

This paper reviews the current problems and prospects to overcome circular water economy management challenges in European countries. The geopolitical paradigm of water, the water economy, water innovation, water management and regulation in Europe, environmental and safety concerns at water reuse, and technological solutions for water recovery are all covered in this review, which has been prepared in the frame of the COST ACTION (CA, 20133) FULLRECO4US, Working Group (WG) 4. With a Circular Economy approach to water recycling and recovery based on this COST Action, this review paper aims to develop novel, futuristic solutions to overcome the difficulties that the European Union (EU) is currently facing. The detailed review of the current environmental barriers and upcoming difficulties for water reuse in Europe with a Circular Economy vision is another distinctive aspect of this study. It is observed that the biggest challenge in using and recycling water from wastewater treatment plants is dealing with technical, social, political, and economic issues. For instance, geographical differences significantly affect technological problems, and it is effective in terms of social acceptance of the reuse of treated water. Local governmental organizations should support and encourage initiatives to expand water reuse, particularly for agricultural and industrial uses across all of Europe. It should not also be disregarded that the latest hydro politics approach to water management will actively contribute to addressing the issues associated with water scarcity.

Effect of anaerobic phases length on denitrifying dephosphatation biocenosis - a case study of IFAS-MBSBBR.

BACKGROUND: The study aimed to evaluate the influence of the duration times of anaerobic phases on the bacterial biocenosis characterisation while denitrifying dephosphatation in the Integrated Fixed-Film Activated Sludge - Moving-Bed Sequencing Batch Biofilm Reactor (IFAS-MBSBBR). The experiment was conducted in a laboratory model. The study consisted of four series, which differed in terms of the ratio of the anaerobic phases. duration concerning the overall reaction time in the cycle. The anaerobic phases covered from 18 to 30% of the whole cycle duration. During the reactor performance that took 9 months, the influent and effluent were monitored by analysis of COD, TKN, NH4-N, NO2-N, NO3-N, TP, PO4-P, pH, alkalinity and the phosphorus uptake batch tests. Characterisation of the activated sludge and the biofilm biocenosis was based on fluorescent in situ hybridisation (identification of PAO and GAO) and the denaturing gradient gel electrophoresis patterns. RESULTS: The organic compounds removal was high (more than 95.7%) independently of cycle configuration. The best efficiency for nitrogen (91.1%) and phosphorus (98.8%) removal was achieved for the 30% share of the anaerobic phases in the reaction time. Denitrifying PAO (DPAO) covered more than 90% of PAO in the biofilm and usually around 70% of PAO in the activated sludge. A substantial part of the polyphosphate accumulating organisms (PAO) community were Actinobacteria. The denitrifying dephosphatation activity was performed mainly by Accumulibacter phosphatis. CONCLUSIONS: High nutrient removal efficiencies may be obtained in IFAS-MBSBBR using the denitrifying dephosphatation process. It was found that the length of anaerobic phases influenced denitrification and the biological phosphorus removal. The extension of the anaerobic phases duration time in the reaction time caused an increase in the percentage share of denitrifying PAO (DPAO) in PAO. The biocenosis of the biofilm and the activated sludge reveal different species patterns and domination of the EBPR community.

Filamentous bacteria in the nitrifying activated sludge.

Filamentous bacteria in addition to wastewater treatment are responsible for the shape of flocs and sedimentation properties of activated sludge. Their dynamics in activated sludge influences the performance of the whole sewage treatment plant. Therefore the composition of activated sludge biocenosis and its dynamics in the nitrification process were investigated. Four laboratory-scale activated sludge membrane bioreactors fed with wastewater highly concentrated with ammonium (synthetic wastewater imitating landfill leachate) were operated to obtain a high rate of nitrification. The sludge age was 8, 12, 24 and 32 days. An additional fifth reactor was conventionally ammonium loaded at 12-day sludge age and served as the reference. A shift in filamentous bacteria population was observed in all operated reactors. There was no influence of sludge age on composition or abundance of filamentous biocenosis. In high ammonium loaded activated sludge Nostocoida limicola, Haliscomenobacter hydrossis and also Type 021N were the most abundant filamentous bacteria. In the reference reactor Type 021N and Sphaerotilus natans dominated the activated sludge.

Accumulation of Metals and Boron in Phragmites australis Planted in Constructed Wetlands Polishing Real Electroplating Wastewater.

The concentration of metals (Al, Cu, Fe, Mn, Ni, Zn) and B were determined in the above- and belowground biomass of Phragmites australis collected from the microcosm constructed wetland system used for the polishing of real electroplating wastewater. Translocation factor and bioconcentration factor were determined. Pearson correlation test was used to determine correlation between metal concentration in substrate and above- and belowground parts of Phragmites australis. The obtained results suggested that Phragmites australis did not play a major role as an accumulator of metals. It was observed also that the substrate could have exerted an effect on the translocation of Ni, Cu, Zn and Mn. The analysed concentrations of metals and B in biomass were in the range or even below the concentrations reported in the literature with the exception of Ni. The aboveground biomass was found suitable as a composting input in terms of metals concentrations.

Detection of sulfonamide resistance genes via in situ PCR-FISH.

Due to the rising use of antibiotics and as a consequence of their concentration in the environment an increasing number of antibiotic resistant bacteria is observed. The phenomenon has a hazardous impact on human and animal life. Sulfamethoxazole is one of the sulfonamides commonly detected in surface waters and soil. The aim of the study was to detect sulfamethoxazole resistance genes in activated sludge biocenosis by use of in situ PCR and/or hybridization. So far no FISH probes for the detection of SMX resistance genes have been described in the literature. We have tested common PCR primers used for SMX resistance genes detection as FISH probes as well as a combination of in situ PCR and FISH. Despite the presence of SMX resistance genes in activated sludge confirmed via traditional PCR, the detection of the genes via microscopic visualization failed.

Resistance of Escherichia coli and Enterococcus spp. to selected antimicrobial agents present in municipal wastewater.

In this study, the susceptibility to erythromycin (E) and to trimethoprim/sulfamethoxazole (SXT) among isolates of Enterococcus spp. and Escherichia coli was tested, respectively. Both fecal indicators were detected and isolated from raw (RW) and treated wastewater (TW) as well as from samples of activated sludge (AS) collected in a local wastewater treatment plant (WWTP). Biodiversity of bacterial community in AS was also monitored using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Additionally, distribution of sul1-3 genes conferring sulfonamide resistance was tested among SXT-resistant E. coli. Simultaneously, basic physicochemical parameters and concentrations of eight antimicrobial compounds (belonging to folate pathway inhibitors and macrolides class) were analyzed in RW and TW samples. Six of the selected antimicrobial agents, namely: erythromycin, clarithromycin, trimethoprim, roxithromycin, sulfamethoxazole, and N-acetyl-sulfamethoxazole were detected in the wastewater samples. Bacterial biodiversity of AS samples were comparable with no relevant differences. Among tested Enterococcus spp., E-resistant isolates constituted 41%. SXT resistance was less prevalent in E. coli with 11% of isolates. The genes conferring resistance to sulfonamides (sul1-3) were detected in SXT-resistant E. coli of wastewater origin with similar frequencies as in other environmental compartments, including clinical ones.

Evaluation of the applicability of selected analytical techniques for determining the characteristics of humic substances sourced from by-products of the wastewater treatment process.

Although humic substances (HSs) are among the most valuable compounds in the environment, they often constitute nuisance factors for wastewater treatment plants (WWTPs). However, their recovery from by-products of WWTPs opens up opportunities for their utilization. Therefore, this study aimed to evaluate the suitability of selected analytical methods for determining the structure, properties, and possible utilization of HSs originating from WWTPs based on model humic compounds (MHCs). As a consequence, the study proposed separate approaches for the initial and in-depth characterization of HSs. The results demonstrate that UV-Vis spectroscopy may be recognized as a cost-effective approach for the preliminary characterization of HSs. Such a method indeed gives similar information on the degree of complexity of MHCs as X-EDS and FTIR, and similarly to them allows for the differentiation of their particular fractions. In turn, X-EDS and FTIR techniques were recommended to be used for in-deep analysis of HSs due to their ability to detect heavy metals and biogenic elements in their structure. Contrarily to other studies, the presented research indicates that only selected absorbance coefficients - A253/A230, Q4/6, and ΔlogK may help to distinguish particular humic fractions and evaluate changes in their behavior, independently of their concentration (coefficient of variation < 20%). Herein, the fluorescence capacities of MHCs were found to be equally affected as their optical properties by the changes in their concentration. Focusing on the obtained results, this study recommends that the quantitative comparison of the properties of HSs should be proceeded by the standardization of their concentration. Herein, the stability of other spectroscopic parameters characterizing solutions MHCs was achieved within a concentration from 40 to 80 mg L-1. Among them, the analyzed MHCs were differentiated the most by the SUVA254 coefficient, which value was almost 4 times higher for SAHSs (8.69) than for ABFASs (2.01).

The population dynamics of nitrifiers in ammonium-rich systems.

Non-optimal pH, dissolved oxygen concentration, the presence of toxic substances, or the influence of grazers are known to cause disturbances in nitrification. Because activated sludge is a mixture of different organisms, bacteria, and higher organisms, the stability of processes such as carbon removal, nitrification, denitrification, and dephosphatation depends on a range of interactions. These interactions occur both between and within trophic levels. Understanding of the ecology of microorganisms involved in bioprocesses is essential for effective control of startup and operation of a particular process. The aim of the study was to gain further insight into the dynamics of nitrifiers in activated sludge at various sludge ages while treating higher concentrations of ammonium. The results confirmed the importance of Nitrosococcus mobilis and Nitrobacter sp. as the dominant nitrifiers responsible for nitritation and nitratation, respectively, in the presence of unlimited ammonium. The size of the dominant bacteria colony was larger compared to the other species present and reached 25 microm. Problems with nitrification occurred in all high-ammonium loaded reactors. The dynamics of nitrifier population was monitored by oxygen uptake rate (OUR) using a test enabling the OUR measurement separately for ammonium-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB). The results reveal the hypersensitivity of nitrifiers to the substrate and products of incomplete nitrification.

Evidence of mutations conferring resistance to clarithromycin in wastewater and activated sludge.

The occurrence of clarithromycin in wastewater samples and of the activated sludge bacteria possibly resistant to this pharmaceutical was the object of the study. Samples of wastewater or activated sludge were taken from a municipal wastewater treatment plant in summer and winter and characterised regarding their clarithromycin concentrations and the presence of nucleic acid fragments (Cla-sequences) known to be responsible for clarithromycin resistance in Helicobacter pylori. The concentrations of clarithromycin in raw wastewater were about 1086-2271 ng/L. Around 50-60% less of the pharmaceutical was found in treated wastewater. The concentrations were much higher in winter samples, as compared to summer samples. The clarithromycin resistance markers in H. pylori were detected by fluorescence in situ hybridisation in activated sludge bacterial cells. Cla-sequences were found in all the detected Proteobacteria, independently of the sampling season. Among nitrifying or phosphate or glycogen accumulating bacteria only Nitrosomonas spp. revealed presence of the clarithromycin sequences.

Molecular analysis of temporal changes of a bacterial community structure in activated sludge using denaturing gradient gel electrophoresis (DGGE) and fluorescent in situ hybridization (FISH).

Wastewater treatment based on activated sludge is known to be one of the most effective and popular wastewater purification methods. An estimation of microbial community variability in activated sludge allows us to observe the correlation between a particular bacterial group's appearance and the effectiveness of the removal of chemical substances. This research is focused on microbial community temporal changes in membrane bioreactors treating wastes containing a high level of ammonia nitrogen. Samples for this study were collected from two membrane bioreactors with an activated sludge age of 12 and 32 days, respectively. The activated sludge microbial community was adapted for the removal of ammonia nitrogen up to a level of 0.3 g NH4(+) - N g/VSS/d (VSS - volatile suspended solids). The methods - denaturing gradient gel electrophoresis (DGGE) based on 16S rRNA gene PCR products and fluorescent in situ hybridization (FISH) with 16S rRNA gene probes - revealed significant differences in the microbial community structure in the two bioreactors, caused mainly by a difference in sludge age. According to the results obtained in this study, a bioreactor with a sludge age of 12 days is characterized by a much higher microbial community diversity than a bioreactor with a sludge age of 32 days. Interestingly, the appearance of particular species of nitrifying bacteria was constant throughout the experiment in both bioreactors. Changes occured only in the case of the Nitrosomonas oligotropha lineage bacteria. This study demonstrates that the bacterial community of bioreactors operating with different sludge ages differs in total community structure. Nevertheless, the changeability of the bacterial community structure did not have any influence on the efficiency of nitrification.

R&D priorities in the field of sustainable remediation and purification of agro-industrial and municipal wastewater.

This article was presented as a position paper during the Environmental Biotechnology and Microbiology Conference in Bologna, Italy in April 2012. It indicates major and emerging environmental biotechnology research and development (R&D) priorities for EU members in the field of sustainable remediation and purification of agro-industrial and municipal wastewater. The identified priorities are: anaerobic/aerobic microbial treatment, combination of photochemical and biological treatment, phytoremediation and algae-based remediation, as well as innovative technologies currently investigated, such as enzyme-based treatment, bioelectrochemical treatment and recovery of nutrients and reuse of cleaned water. State of the art, research needs and prospective development in these domains are crucially discussed. As a result, goals of the future development of bioremediation and purification processes are defined and the way to achieve them is proposed.