Past mining activities in the area of Silvermines, Ireland, have resulted in heavily polluted soils. The possibility of spreading pollution to the surrounding areas through dust blow-offs poses a ...potential threat for the local communities. Conventional environmental soil and dust analysis techniques are very slow and laborious and consequently there is a need for fast and accurate analytical methods, which can provide real-time in situ pollution mapping.
Laboratory-based aqua regia acid digestion of the soil samples collected in the area followed by the atomic absorption spectrophotometry (AAS) analysis confirmed very high pollution, especially by Pb, As, Cu, and Zn. In parallel, samples were analyzed using portable X-ray fluorescence radioisotope and miniature tube powered (XRF) NITON instruments and their performance was compared. Overall, the portable XRF instrument gave excellent correlation with the laboratory-based reference AAS method.
Simple, robust, and low-cost nitrate- and ammonium-selective electrodes were made using substrate prepared from household materials. We explored phosphonium-based ILs and poly (methyl ...methacrylate)/poly(decyl methacrylate)(MMA-DMA) copolymer as matrix materials alternative to classical PVC-based membranes. IL-based membranes showed suitability only for nitrate-selective electrode exhibiting linear concentration range between 5.0 × 10
and 2.5 × 10
M with a detection limit of 5.5 × 10
M. On the other hand, MMA-DMA-based membranes showed suitability for both ammonium- and nitrate-selective electrodes, and were successfully applied to detect NO₃
and NH₄⁺ in water and soil samples. The proposed ISEs exhibited near-Nernstian potentiometric responses to NO₃
and NH₄⁺ with the linear range concentration between 5.0 × 10
and 5.0 × 10
M (LOD = 11.3 µM) and 5.0 × 10
and 1.0 × 10
M (LOD = 1.2 µM), respectively. The power of ISEs to detect NO₃
and NH₄⁺ in water and soils was tested by comparison with traditional, portable colorimetric techniques. Procedures required for analysis by each technique from the perspective of a non-trained person (e.g., farmer) and the convenience of the use on the field are compared and contrasted.
The production of metabolites in microalgae is influenced by extreme cultivation conditions. Bicarbonate is an inorganic carbon source for phototrophic microalgae culturing. In this study, the effect ...of dissolved inorganic carbon (DIC) (0.4–13 g L
−1
) on the accumulation of metabolites in
Dunaliella tertiolecta
biomass is presented. The highest levels of primary metabolites lipid (239.6 ± 24.3 mg g
−1
), protein (336.2 ± 47.5 mg g
−1
), secondary metabolites total phenolic (12.8 ± 2.0 mg g
−1
), total flavonoid (14.4 ± 2.3 mg g
−1
), total ascorbate (4.7 ± 1.1 mg g
−1
), and pigments chlorophyll (27.2 ± 3.1 mg g
−1
), carotenoid (2.0 ± 0.1 mg g
−1
) were observed when cells were grown with 5.7 g L
−1
of DIC (NaHCO
3
)
.
The highest biomass concentrations (1.5 ± 0.1 g L
−1
) were obtained for cells grown in a mixture of DIC (4.3 + 1.1 g L
−1
, NaHCO
3
+ Na
2
CO
3
). This study recommends the optimal levels of bicarbonate carbon of 5.7 g L
−1
for maximising the generation of metabolites in the biomass. It also demonstrates that exogenous excessive DIC in the growth medium would be an effective stressor to produce high-value metabolites in
Dunaliella
or alkali-halophilic strains.
Graphical Abstract
An overview is given dealing with application of ion-selective electrodes
(ISEs) in environmental analysis. ISEs are placed into the context of the
trend of development of sensors for extensive and ...frequent monitoring.
Discussed are the issues such as sensing platforms and their mass-production,
improvement of precision, diagnostic of sensor?s functionality, and
development of reference electrodes and several examples of real-life
application of ISEs in environmental analysis are given. The main emphasis of
this article is directed towards summarizing recent of authors? results
during the past several years.
nema
In recent decades, biogas production from anaerobic digestion of organic fractions of municipal solid waste and agricultural residues has emerged as a promising strategy for waste management and ...renewable energy generation. However, due to the complexity and heterogeneity of these feedstocks, an appropriate pre-treatment is required before anaerobic digestion to maximise biodegradability and enhance biogas production. This is especially true for lignocellulosic biomass, where maximum biogas potential is often difficult to reach due to the presence of a lignin barrier, which is not easily biodegradable. Pre-treatment technologies may significantly increase biogas production, up to 360 %, from organic fractions of municipal solid waste and agricultural residues. This paper first provides an overview of the pre-treatment technologies, including mechanical, chemical, biological, thermal, plasma, and combined treatments for a wide variety of feedstocks for biogas production from anaerobic digestion. These studies indicate that the selection of a pre-treatment technology mainly depends on the waste substrate characteristics, the desired end results, and resource availability. Furthermore, most studies emphasise the significance of balancing the benefits and drawbacks of pre-treatment technologies for sustainable waste-to-energy practices. Then, the article evaluates the scalability, technical feasibility, economic viability, industrial applicability and environmental sustainability of appropriate pre-treatment methods. This review will be a valuable resource for researchers, policymakers, and practitioners working in the field of waste-to-energy conversion through anaerobic digestion.
•Pre-treatment enhances biodegradability and biogas production from lignocellulosic feedstock.•Variability of lignocellulosic feed necessitates novel and effective pre-treatment methods.•Effectiveness, cost, scalability, and sustainability dictate industrial applicability.•Up to 360 % improvement in AD biogas yields was reported with pre-treatment.•Choosing a suitable pretreatment requires a comprehensive context-specific approach.
This study investigates the potential of hydrothermal carbonisation (HTC) for fractionating anaerobic digestate of sewage sludge into carbon-rich hydrochar and nutrient-rich aqueous phase (AP). AP is ...subsequently used to supplement cultures of the alkali halophilic microalgae D. tertiolecta (CCAP 19/30), to convert sodium bicarbonate into sodium carbonate solution as part of an integrated biogas purification system. HTC at 200 °C gave the highest hydrochar yields (78%) and solid carbon retentions (75%), indicating high carbon capture potential. In contrast, the essential growth nutrients nitrogen, phosphorus and sulphur were partially solubilised, resulting in HTC-AP concentrations between 11 times (S) and 50 times (P) higher than those in artificial growth medium. Trace nutrient concentrations in the AP were 10–80 times higher compared to the artificial medium, with minimal heavy metal solubilisation. Dunaliella tertiolecta grew successfully and without inhibition at HTC-AP concentrations up to 2% (produced at 200 °C). AP-supplemented cultures achieved higher cell concentrations (up to 10.0 ×106 cells mL−1), biomass content (maximum of 1.14 ± 0.06 g L−1) and bicarbonate-to-carbonate conversion (83% and 80%, for 1% and 2% of HTC-AP) than the control cultures. Therefore, HTC-AP appears to be a suitable artificial growth medium substitute for cultivating alkali-halophilic microalgae to regenerate carbonate and produce algae biomass, providing an added-value product.
•HTC of anaerobic digestate achieves up to 74.4% carbon recovery in hydrochar.•Nutrient concentrations in aqueous phase (AP) 11–50 x higher than artificial medium.•D. tertiolecta successfully grown with AP concentrations up to 2% (HTC at 200 °C).•Biomass yields and bicarbonate conversion in HTC-AP exceed the control.
This paper presents a new integrated process for producing carbon-negative biomethane fuel which combines anaerobic digestion of sewage sludge with biogas purification, algae generation and carbon ...capture. Biogas CO2 is recovered through absorption into sodium carbonate solution, producing bicarbonate, subsequently used as substrate for algae growth. Anaerobic digestate is hydrothermally carbonised into biochar, stabilising unused biomass carbon for long-term storage.
Proof-of-concept studies are provided, together with a system carbon balance to demonstrate its overall carbon capture potential. D. tertiolecta (CCAP 19/30) was cultivated at different bicarbonate concentrations (2.5–90 g L−1), producing equimolar amounts of carbonate and carbon-derived products (algae, gaseous CO2). Above 40 g L−1, carbonate regeneration significantly exceeded algae growth, achieving higher than expected CO2 uptake potential, but lower overall carbon sequestration potential due to the discharge of excess CO2 to the environment. Single-stage CO2 absorption from a model biogas mixture (60% methane) into carbonate solution was rate limited by the reaction of dissolved CO2 with solution hydroxide ions, achieving steady state methane outlet purities of up to 85%. Spent absorbent was successfully used for algae culture, and the regenerated medium showed equivalent CO2 uptake as the fresh carbonate solution, demonstrating the cyclability of the system. Carbon distribution to biochar and algae by-products was estimated as 35.1%, exceeding the expected emissions associated with the process, to render the process carbon negative.
•New process integrates algae-based CO2 capture with HTC of digestate•D. tertiolecta CCAP 19/30 regenerates carbonate at concentrations up to 80 g L−1•Above 40 g L−1, bicarbonate conversion exceeds algae growth, releasing excess CO2•Spent growth medium successfully used for biogas purification•27% of feed carbon captured in biochar rendering process net carbon negative
Black-odorous water, which exists widely in rural areas of China, affects the living environments of residents and causes a loss of ecosystem functions, and improper treatment may even cause ...secondary pollution. Moreover, the transformation relationships among the components of humus in the sediments of black-odorous water are largely unknown. Therefore, it is necessary to select appropriate methods for treating black-odorous water in rural areas and to understand the characteristics of humus in sediment during the treatment process. In this study, the use of aeration in treating black-odorous water and interstitial water in rural areas was studied and the effects of different treatment methods on the contents and spectral characteristics of humus components in sediments were explored. It was found that the quality of the treated water improved from severe black-odorous to nonblack-odorous, the colour of the sediment changed from black to greyish-brown to turquoise, and the odour changed from strong to weak. The removal rates of ammonia nitrogen, total nitrogen, total phosphorus, and chemical oxygen demand in the sediment aeration group reached more than 50% in the upper water, and more than 70% in the interstitial water. After treatment, the content of fulvic acid, the main black substance in sediment, decreased by 0.36–1.58 g/kg, and the molecular structure of the humus was simplified.
Display omitted
•Aeration treatment can improve rural water from severe black-odorous to nonblack-odorous.•Removal effect of pollutants in rural black-odorous water by sediment aeration is better.•The changes in humus spectral characteristics after aeration treatment were analysed.•The contents of humus, HA, and HM and the PQ values in the sediment aeration are higher.
Due to severe disturbances caused by rapid urbanization and industrialization, river ecosystems have evolved into complex natural-social composite ecosystems. At present, there is no unified ...evaluation method for the effect of river restoration in China. The existing research fails to fully integrate the “natural-social” characteristics of rivers, and pays less attention to the river section scale, which is not conducive to the development of accurate pollution control work. In this paper, we first put forward the division method of river section type which conforms to the “nature-society” dual attribute characteristics of the river, and divides the river section into “ecological/service/dual” functional “urban/rural” river section. Then a method for evaluating the restoration effect of different river sections based on index weight optimization was proposed. Based on the type of river section, the weights of 17 indexes were optimized, and the common evaluation method of restoration effect—multi-index evaluation method was improved. In addition, the application and verification of the established method were carried out on the main stream of Qingyi River and its typical tributaries. The evaluation results show that only the restoration effect of Baling River decreased from average in 2019 to acceptable in 2021, and ΔH (the change of the mean score of the target factor after repair) decreased from 15.6% to 6.2%. It was found that for the river sections where the repair effect cannot be maintained stably (such as Baling River), the previous methods paid more attention to the overall effect and easily ignored the specific problems. The improved method can identify problems more easily and facilitate timely post-maintenance. To further optimize the repair effect of Qingyi River, it is suggested that the restoration effect should be strengthened from the aspects of pollution source control, water quality improvement, aquatic restoration, continuous monitoring and evaluation. The evaluation results can provide a reference for the design, operation, and maintenance of restoration projects in small and medium-sized rivers.
•Proposed an evaluation method of restoration effect based on river sections.•Classify river reach types based on administrative location and dominant functions.•The improved method optimizes the index weight and evaluation criteria.•The improved method can find out the problems in the river section in time.
Display omitted
•A new framework to quantify key components of municipal solid waste (MSW) residues.•Hydrothermal liquefaction (HTL) yields validate results of the proposed framework.•Biooil yields ...are correlated with the cellulose content of MSW residues.•MSW residue plastic fractions are recovered in HTL solids products.•HTL is suitable for high-ash content MSW residues.
This paper presents and evaluates a new method for characterising municipal solid waste residues for assessing the performance of thermochemical conversion technologies to produce fuels. The method combines information from three complementary analytical techniques to estimate the quantity of key organic waste fractions and was demonstrated using two commercial waste residues: ‘BRDF’ and ‘Floc’ produced from the mechanical processing of domestic waste. Cellulose content (mostly paper and textiles) is estimated using acid hydrolysis, while thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) are combined to determine the plastics (LDPE and PET) and non-volatile fractions such as lignin of the wastes. High mass balance closures were achieved for both residues, although the nature of the non-volatile fraction was difficult to verify. Hydrothermal liquefaction (HTL) of cellulose rich BRDF (34.0% cellulose) produced much higher biooil yields than Floc (26.8% and 12.2%, respectively), with a cellulose content of only 22.4%. In both cases, most of the plastic and non-volatile waste fractions partitioned into the solid HTL product, representing a potential method for separating the plastic fractions from other waste components. Importantly, this combined waste characterization method can be used for characterization of any municipal waste residue using acid hydrolysis, TGA and FTIR data, providing accurate information about feedstock composition. It enables comparison between different waste valorisation studies of complex waste residues.
PDF
