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Global increase in aquaculture production has created a need to reduce its environmental impacts. Nutrients could be recycled especially at land-based recirculating aquaculture systems (RAS) by cultivating green microalgae in aquaculture effluent. However, microalgae are difficult to harvest. As a multi-trophic solution, mussels could be used in harvesting microalgae. We tested three European freshwater mussels (duck mussel Anodonta anatina, swan mussel A. cygnea, and swollen river mussel Unio tumidus) for filtering two common green microalgae (Monoraphidium griffithii and Selenastrum sp.) grown in RAS effluent. Mussels decreased microalgal concentrations in the tanks 42–83% over three consecutive trials. Algal concentrations at the end of each trial were lowest for both microalgae in tanks containing Anodonta mussels. Clearance rates were higher for Anodonta mussels than for U. tumidus. Mussels biodeposited more microalgae to tank bottoms when M. griffithii was filtered. Ammonium concentration decreased or did not change in tanks with M. griffithii, but increased in tanks containing Selenastrum sp. These results suggest that of the tested species Anodonta mussels and M. griffithii show best potential for RAS effluent bioremediation application. We conclude that a co-culture of microalgae and unionid mussels could be used for recycling nutrients in aquaculture. [ABSTRACT FROM AUTHOR]

Termites—one of the most abundant animal groups in tropical ecosystems—are vital in nutrient recycling, contributing significantly to maintaining ecosystem functioning. However, how selective they are in their litter food choice, and whether they prefer nutritious or less nutritious litter substrates, are still important unresolved questions.Here, we test the effect of litter traits on the removal of litter by fungus‐growing termites, a dominant group of macrodetritivores in the Serengeti‐Mara ecosystem. We used metal‐mesh litterbags to measure the mass loss of stem and leaf litter from 23 grass species after an incubation period of 61 days.Sheeting—soil deposits indicating termite presence—strongly increased with tannin and phenolic compounds, especially in leaf litter (R2 = 0.54), where highly aromatic species like Cymbopogon caesius and Bothriochloa insculpta exhibited the highest sheeting rates. Litterbags with sheeting displayed 66% higher mass loss on average compared to those without. Once termites had selected the substrate, mass loss increased consistently irrespective of litter traits.Quantifying the combined effects of sheeting frequency and differential mass loss, we found that fungus‐growing termites predominantly increased the mass loss of high‐nutrient litter. This was mainly due to additional mass loss in leaf litter, not stem litter, with tannin concentration being the primary predictor of enhanced overall decomposition by termites. This suggests termites ameliorate the otherwise adverse influence of plant secondary compounds on litter decomposition.Synthesis: Our results support the idea that fungus‐growing termites are generalists, as termites collected organic substrates with varying quality. The strong effect of phenolic compounds on sheeting rate implies that secondary compounds play an important role in termite substrate selection. The selective removal of substrates high in secondary compounds suggests fungus‐growing termites lift important constraints to microbial breakdown, potentially enhancing ecosystem‐level carbon and nutrient recycling rates. Termites play crucial roles in recycling organic matter across tropical biomes and our study highlights that the role of secondary compounds in their selection and detection in decomposition studies needs more attention [ABSTRACT FROM AUTHOR]

With increases in global population and urbanization, the production of Municipal Solid Waste (MSW) is growing rapidly, thus contributing to social and environmental concerns for sustainable waste management. This study addresses the research gap in optimizing composting, hypothesizing that integrating best practices and recent innovations can enhance the efficiency of the process. Data were collected through a systematic review of existing literature using Google Scholar and Scopus databases. The review provides an overview of municipal organic waste composting, outlining its processes, benefits, and challenges with the aim of identifying key area of further improvement and possibilities of adopting recent technological innovations. The analysis emphasized that technological advances in composting, as microbial inoculants or in-vessel composting have greatly improved the efficiency and quality of the resulting compost. However, several challenges remain, including managing contaminants such as heavy metals and microplastics, ensuring the compost quality and safety and addressing socioeconomic barriers that prevent widespread adoption. Moreover, process optimization, environmental and economic evaluation, as well as political and public involvement are essential to unlock the whole potential of composting systems. [ABSTRACT FROM AUTHOR]

Applying sewage sludge and biosolids to agricultural lands has become an increasingly essential aspect of sustainable waste management and circular economy as it contributes positively to nutrient recycling, soil fertility and environmental health. Due to the widespread presence of per and polyfluoroalkyl substances (PFAS) globally, wastewater treatment plants have become a sink for PFAS. PFAS resist degradation by conventional wastewater treatment processes and are usually adsorbed to sewage sludge and biosolids. However, there have been significant concerns that land application of sewage sludge and biosolids could become a probable pathway for PFAS to enter the food chain. This article assessed the global sewage sludge/biosolids generation and country-to-country management methods through a systematic review. The global occurrence, distribution and prevalence of different classes of PFAS were assessed. We also evaluate the factors influencing PFAS contamination in sewage sludge/biosolids and the existing regulations on the upper limit of PFAS in biosolids before their disposal or application to farmland (or other usages). Additionally, most reports revealed high PFAS concentrations in influent, effluent, sewage sludge and biosolids generated worldwide. Overall, recorded PFAS concentration on a global scale varied from 2.2 to 2,156 ng/L (influents), 1.9-4,800 ng/L (effluents) and 2.1-500,000 ng/g (biosolids). While most studies focused on legacy PFAS detection, recent studies have revealed the prevalence of diPAPs in high concentrations in sewage sludge and biosolids, contributing from 40% to 95% of the total PFAS concentration. Across all PFAS classes, PFAAs and diPAPs were the dominant groups exhibiting elevated detection rates (35%-95%). Due to documented PFAS contamination in agricultural lands, rigorous regulations need to be instituted to govern the application of these biowastes on agricultural lands. However, several countries lack data on the level of PFAS in the sewage sludges they generate, and there are currently few or no regulations guiding their application to farmlands. Notably, the diPAPs class of PFAS was shown to be present in biosolids and sewage sludge; their inclusion in the list of PFAS required in standardized analytical methods and risk assessment becomes imperative. [ABSTRACT FROM AUTHOR]

We evaluated the operational, financial, and management challenges within China's Toilet Revolution by surveying 656 rural households across 10 provinces. The results revealed that the majority of households which renovated their toilets under the Toilet Revolution perceived positive impacts of this on their quality of life and living conditions. Households that had undertaken toilet renovations viewed the program more favorably than households which had not undertaken renovation, and were more willing to engage with the program. Despite the perceived benefits, households were generally hesitant to personally invest in toilet renovation. We uncovered a gap in strategic sanitation planning for post-construction operation and maintenance of toilets, reflecting a "build first, manage later" approach in the Toilet Revolution. We also identified a widespread lack of formal models for management of toilets and toilet products, coupled with high reliance among households on government support and subsidies to fund renovation. To address operational inefficiencies and financial sustainability issues in the program, we propose a novel "Toilet Business" model that leverages a sanitation value chain approach. In this model, private sector engagement, cost management, and market revitalization are crucial components that must be implemented to ensure the program's long-term success. Overall, our study provides valuable insights into the complexities of implementing large-scale sanitation programs such as the Toilet Revolution. [ABSTRACT FROM AUTHOR]

Recycling and reusing phosphorus in agriculture can reduce the consumption of natural phosphorus resources, which are continuing to shrink. Phosphorus fertilizers made from renewable raw materials (sewage sludge ash, animal bones, dried animal blood) and activated with phosphorus solubilizing microorganisms (Bacillus megaterium, Acidithiobacillus ferrooxidans) offer an alternative to conventional fertilizers. These products should meet consumer and environmental safety standards. In this paper, based on field experiments conducted in northeast Poland, the effects of waste-derived biofertilizers on selected parameters of wheat yield quality are discussed. The study focuses on the technological properties of the grain (hectoliter weight, hardness index, Zeleny index, starch, wet gluten, and protein content), the content of proteogenic amino acids, macro- and micronutrients, and selected toxic elements in the grain. The quality parameters of wheat grain were not affected by the tested biofertilizers applied in P doses up to 35.2 kg ha−1, nor by conventional fertilizers. [ABSTRACT FROM AUTHOR]

Volcanic tuffs rich in chabazite zeolites have been extensively examined for their potential to enhance soil properties and increase fertilizer efficiency, both in their natural state and when enriched with nitrogen (N). However, there is a scarcity of data regarding their utilization in acidic sandy soil, particularly when used alongside organic fertilizers. This paper presents the findings of a 50-day laboratory incubation study that investigated the dynamics of N pools in an acidic sandy-loam agricultural soil treated with various N sources. These sources included urea, N-enriched chabazite zeolite tuff, and pelleted composted manure applied at a rate of 170 kg N/ha. Additionally, the N sources were tested in combination with chabazite zeolite tuff mixed into the soil to assess its role as a soil conditioner. The results revealed distinct behaviours among the tested N sources, primarily impacting soil pH and N dynamics. Soil fertilized with manure exhibited slow N mineralization, whereas N-enriched zeolite displayed a more balanced behaviour concerning net NO3−-N production and NH4+-N consumption. Both N-enriched zeolite and urea temporarily altered the soil pH, resembling a "liming" effect, while pelleted manure facilitated a prolonged shift towards neutral pH values. Considering the water adsorption capacity of zeolite minerals, caution is advised when adjusting water content and employing combustion methods to measure soil organic matter in zeolite-treated soil to avoid potential inaccuracies. In summary, N-enriched chabazite zeolite tuff emerged as a valuable N source in acidic sandy-loam soil, offering a promising alternative to synthetic fertilizers and showcasing a sustainable means of N recycling. [ABSTRACT FROM AUTHOR]

Introduction: Production of strawberries in greenhouses and polytunnels is gaining popularity worldwide. This study investigated the effect of reuse of coir and peat, two substrates commonly adapted to soilless strawberry production, as well as stand-alone wood fiber from Norway spruce, a promising substrate candidate. Methods: The experiment was performed in a polytunnel at NIBIO Apelsvoll, Norway, and evaluated both virgin substrates, as well as spent materials that were used in one or two years. Yield, berry quality and plant architecture of the strawberry cultivar 'Malling Centenary' were registered. In addition, chemical and physical properties of virgin and reused substrates were investigated. Results: While plants grown in peat and wood fiber had highest yield in the first year of production, the berry yield was slightly reduced when these substrates were utilized for the second and third time. However, yield was comparable to the yield level attained in new and reused coir. Interestingly, berries grown in wood fiber had a tendency to a higher sugar accumulation. This substrate also produced the highest plants. Stand-alone wood fiber was the substrate with the highest accumulation of nitrogen during the three consecutive production cycles. All three investigated materials revealed a trend for decreased potassium accumulation. Wood fiber is characterized by the highest percentage of cellulose, however after three years of production the cellulose content was reducedto the same levels as for coir and peat. Discussion: Implementation of wood fiber as a growing medium, as well as general practice of substrate reuse can be therefore an achievable strategy for more sustainable berry production. [ABSTRACT FROM AUTHOR]

A constant source of nutrient pollution that causes eutrophication is municipal wastewater treatment plant (WWTP) secondary effluent. This paper investigates the natural increase of pH, nutrient removal and biomass production from a cyclical re-cultivation system designed to favor the adaptation of microalgae consortia to WWTP secondary effluent. An outdoor experiment was performed with the microalgae consortia MC-10 under 3 sequential batch cycles. The natural pH increase (range 9-10) in the WWTP secondary effluent was established as an operation parameter because it certainly influenced microalgae biomass production (by maintenance and bioavailability of C and P), water treatment and pathogen removal. The increase of pH (9.7, 9.8 and 9.9) during the culture cycles of MC-10 probably generated conditions for fecal bacterial removal below detectable values (i.e., < 2 MPN/100 mL). The treatment of WWTP secondary effluent after batch cycles (cycles 1 to 3) using MC-10 indicated improvements in biomass productivity (66 to 167%) and a great potential for the reduction of total alkalinity (13.1 to 50.3%), NO3--N (30.9 to 53.6%), PO43- - P (90.4 to 93.0%) and electrical conductivity (EC) (8.5 to 18.1%). Additionally, the harvested biomass showed a high mineral concentration (46.5%) suggesting its potential use as a bio-fertilizer. [ABSTRACT FROM AUTHOR]

Applying sewage sludge and biosolids to agricultural lands has become an increasingly essential aspect of sustainable waste management and circular economy as it contributes positively to nutrient recycling, soil fertility and environmental health. Due to the widespread presence of per and poly-fluoroalkyl substances (PFAS) globally, wastewater treatment plants have become a sink for PFAS. PFAS resist degradation by conventional wastewater treatment processes and are usually adsorbed to sewage sludge and biosolids. However, there have been significant concerns that land application of sewage sludge and biosolids could become a probable pathway for PFAS to enter the food chain. This article assessed the global sewage sludge/biosolids generation and country-to-country management methods through a systematic review. The global occurrence, distribution and prevalence of different classes of PFAS were assessed. We also evaluate the factors influencing PFAS contamination in sewage sludge/biosolids and the existing regulations on the upper limit of PFAS in biosolids before their disposal or application to farmland (or other usages). Additionally, most reports revealed high PFAS concentrations in influent, effluent, sewage sludge and biosolids generated worldwide. Overall, recorded PFAS concentration on a global scale varied from 2.2 to 2,156 ng/L (influents), 1.9–4,800 ng/L (effluents) and 2.1–500,000 ng/g (biosolids). While most studies focused on legacy PFAS detection, recent studies have revealed the prevalence of diPAPs in high concentrations in sewage sludge and biosolids, contributing from 40% to 95% of the total PFAS concentration. Across all PFAS classes, PFAAs and diPAPs were the dominant groups exhibiting elevated detection rates (35%–95%). Due to documented PFAS contamination in agricultural lands, rigorous regulations need to be instituted to govern the application of these biowastes on agricultural lands. However, several countries lack data on the level of PFAS in the sewage sludges they generate, and there are currently few or no regulations guiding their application to farmlands. Notably, the diPAPs class of PFAS was shown to be present in biosolids and sewage sludge; their inclusion in the list of PFAS required in standardized analytical methods and risk assessment becomes imperative.

Animal excretion provides nutrients for primary productivity and can be a crucial component of ecosystem nutrient cycling. The concentrations of carbon (C), nitrogen (N), and phosphorus (P) in an animal's excretion are strongly influenced by the C:N:P stoichiometry (molar ratios) of its body and of the food it eats. We measured the C:N:P ratios of quagga mussel (Dreissena rostriformis bugensis) tissues and excreta and of seston across wide environmental and spatial gradients in the upper Laurentian Great Lakes. We then investigated how mussel excretion rates were impacted by stoichiometric mismatch—the difference between the C:P ratios of mussel tissues and the C:P ratios their food. Quagga mussel internal C:N:P stoichiometry varied significantly across sites and seasons, driven primarily by changes in tissue P concentrations. When mussel tissues had substantially lower C:P ratios than seston (that is, strong stoichiometric mismatch), mussels excreted significantly less N and P relative to C. Excretion C:N ratios varied by nearly threefold, while C:P ratios varied by tenfold. The effect of the stoichiometric mismatch on excretion stoichiometry was more dramatic in the spring, when mussels had higher tissue P concentrations, than in the summer. This suggests seasonality in mussel P demand. Our results challenge the assumption of strict internal homeostasis in consumers and demonstrate that food and tissue stoichiometry need to be considered to predict consumer excretion stoichiometry. These findings help to better understand the impact of consumer-driven nutrient cycling in aquatic environments and quagga mussel contributions to the nutrient budgets of invaded ecosystems. [ABSTRACT FROM AUTHOR]

Recycling resources excreted in human urine can help achieve a sustainable future and circular economy in the sanitation space. However, many studies researching different technologies for safely recycling urine do not use real human urine for experimentation, relying instead on recipes for making synthetic or artificial solutions that attempt to mimic the composition of real human urine. This methodological choice is the focus of this article, which points out that the real urine matrix is extremely complex, with a metabolome (>2,500 metabolites) that differs greatly from that of synthetic urine (

Agricultural crop residues include leftover and unmarketable materials, such as crop stover, weeds, leaf litter, sawdust, forest litter, and livestock manure originating from crop cultivation, and post-harvest activities. Such residues are a storehouse of plant nutrients and several other resources and therefore need to be managed in an environment- friendly manner with minimum loss of plant nutrients and other resources that can be recovered. Microbial starter consortia are a key component in the rapid recycling of farm residue wastes and the production of other valuable products, such as biogas, bioethanol/biofuel, enzymes, molecules, and metabolites. Recent advances in microbial biotechnology can also facilitate the conversion of farm residues into economically valuable materials, i.e. soil additives, adsorbents, energy, and enzymes, thereby contributing to a circular economy. This special issue attempts to compile the latest advancements in the field of agricultural crop residue management for enhanced nutrient recycling and resource recovery by the use of compost starters and inoculant formulations.

Nutrient availability plays a crucial role in microalgae growth in domestic wastewater. In this study, we investigated the impact of different nitrogen and phosphorus ratios (5:1, 10:1, and 20:1, m∙m−1), and the addition of inorganic carbon on microalgae growth and nutrient uptake from domestic wastewater. Microalgae biomass achieved values ranging from 0.54 to 1.41 g·L−1. The cultivation process had maximum removal efficiencies of 83.7% for soluble chemical oxygen demand (sCOD), 74.0% for total Kjeldahl nitrogen (TKN), and 100.0% for ammonia (NH3) and orthophosphate (PO43−). All the NH3 and PO43− concentrations from domestic wastewater without supplementation were completely removed on the fourth day of cultivation. Moreover, no significant differences in microalgae growth, and NH3 and PO43− removals were observed between the conditions with and without nutrient supplementation on the fourth day of cultivation. This study has shown the feasibility of growing microalgae in domestic wastewater without any nutritional supplementation. Further investigations are required to check the long-term performance, energy requirements, and economic viability of this system for wastewater treatment and the production of nutrient-rich biomass for agricultural applications.

Recycling and reusing phosphorus in agriculture can reduce the consumption of natural phosphorus resources, which are continuing to shrink. Phosphorus fertilizers made from renewable raw materials (sewage sludge ash, animal bones, dried animal blood) and activated with phosphorus solubilizing microorganisms (Bacillus megaterium, Acidithiobacillus ferrooxidans) offer an alternative to conventional fertilizers. These products should meet consumer and environmental safety standards. In this paper, based on field experiments conducted in northeast Poland, the effects of waste-derived biofertilizers on selected parameters of wheat yield quality are discussed. The study focuses on the technological properties of the grain (hectoliter weight, hardness index, Zeleny index, starch, wet gluten, and protein content), the content of proteogenic amino acids, macro- and micronutrients, and selected toxic elements in the grain. The quality parameters of wheat grain were not affected by the tested biofertilizers applied in P doses up to 35.2 kg ha−1, nor by conventional fertilizers.

Societies have always been occupied with securing food supply and ensure environmental and human health. Scientific knowledge and technical level have, together with habitat and management patterns, shaped sanitation arrangements and recycling of resources. Because it is the same urban problems that are addressed by societies in different historical contexts, a longitudinal study may allow for novel ways to conjure food security and sanitation management issues in the present century.We trace the historical transition over two centuries away from a circular economy to a more linear one in two Swedish cities, the capital Stockholm and the industrial city Norrköping, and show that big but rather slow changes occurred more or less constantly in these two urban settings. The driving forces have changed from only improving local conditions of sanitation and food production over to global and regional driving forces in this century affecting what local communities can or could do. The ongoing globalization positions the subjects of environmental and human health, recycling and food security in a new global perspective, where climate change and global resource boundaries will play a central role. We cannot continue to rely on trade that causes rainforest destruction elsewhere or harmful chemical consumer products that lead to loss of biodiversity and human health risks.We need to put urban sanitation and food issues into this wider perspective with available remedial measures such as dietary changes, food waste reduction, soil less food production and building of new circular infrastructure. All urban areas in the world, including Stockholm and Norrköping in Sweden, need to adopt new strategies that again engage residents as well as public sectors and industry, including agriculture.

Nutrient availability plays a crucial role in microalgae growth in domestic wastewater. In this study, we investigated the impact of different nitrogen and phosphorus ratios (5:1, 10:1, and 20:1, m∙m−1), and the addition of inorganic carbon on microalgae growth and nutrient uptake from domestic wastewater. Microalgae biomass achieved values ranging from 0.54 to 1.41 g·L−1. The cultivation process had maximum removal efficiencies of 83.7% for soluble chemical oxygen demand (sCOD), 74.0% for total Kjeldahl nitrogen (TKN), and 100.0% for ammonia (NH3) and orthophosphate (PO43−). All the NH3 and PO43− concentrations from domestic wastewater without supplementation were completely removed on the fourth day of cultivation. Moreover, no significant differences in microalgae growth, and NH3 and PO43− removals were observed between the conditions with and without nutrient supplementation on the fourth day of cultivation. This study has shown the feasibility of growing microalgae in domestic wastewater without any nutritional supplementation. Further investigations are required to check the long-term performance, energy requirements, and economic viability of this system for wastewater treatment and the production of nutrient-rich biomass for agricultural applications. [ABSTRACT FROM AUTHOR]

Incorporating a variety of microalgae into wastewater treatment is considered an economically viable and environmentally sound strategy. The present work assessed the growth characteristics of Chlorella sorokiniana during cultivation in balanced synthetic media and domestic wastewater. Increasing the NH4+–N concentration to 360 mg L−1 and adding extra PO43−–P and SO42−–S (up to 80 and 36 mg L−1, respectively) contributed to an increase in the total biomass levels (5.7–5.9 g L−1) during the cultivation of C. sorokiniana in synthetic media. Under these conditions, the maximum concentrations of chlorophylls and carotenoids were 180 ± 7.5 and 26 ± 1.4 mg L−1, respectively. Furthermore, when studying three types of domestic wastewaters, it was noted that only one wastewater contributed to the productive growth of C. sorokiniana, but all wastewaters stimulated an increased accumulation of protein. Finally, the alga, when growing in optimal unsterilized wastewater, showed a maximum specific growth rate of 0.73 day−1, a biomass productivity of 0.21 g L−1 day−1, and 100% NH4+–N removal. These results demonstrate that the tested alga actively adapts to changes in the composition of the growth medium and accumulates high levels of protein in systems with poor-quality water. [ABSTRACT FROM AUTHOR]

The exchange of material and individuals between neighboring food webs is ubiquitous and affects ecosystem functioning. Here, we explore animal foraging movement between adjacent, heterogeneous habitats and its effect on a suite of interconnected ecosystem functions. Combining dynamic food web models with nutrient‐recycling models, we study foraging across habitats that differ in fertility and plant diversity. We found that net foraging movement flowed from high to low fertility or high to low diversity and boosted stocks and flows across the whole loop of ecosystem functions, including biomass, detritus, and nutrients, in the recipient habitat. Contrary to common assumptions, however, the largest flows were often between the highest and intermediate fertility habitats rather than highest and lowest. The effect of consumer influx on ecosystem functions was similar to the effect of increasing fertility. Unlike fertility, however, consumer influx caused a shift toward highly predator‐dominated biomass distributions, especially in habitats that were unable to support predators in the absence of consumer foraging. This shift resulted from both direct and indirect effects propagated through the interconnected ecosystem functions. Only by considering both stocks and fluxes across the whole loop of ecosystem functions do we uncover the mechanisms driving our results. In conclusion, the outcome of animal foraging movements will differ from that of dispersal and diffusion. Together we show how considering active types of animal movement and the interconnectedness of ecosystem functions can aid our understanding of the patchy landscapes of the Anthropocene. [ABSTRACT FROM AUTHOR]

Decomposition is a major contributor to ecosystem respiration, determining the carbon emission and nutrient cycling rates. Our current understanding of decomposition dynamics and their underlying drivers has mainly focused on surface habitats but largely ignored in subterranean environments. Here we studied abiotic and microbial drivers of early-stage litter decomposition inside and outside caves along an elevational gradient in Tenerife. We found comparable decomposition rates (k) and litter stabilizing factors (S), with contrasting drivers and elevational variation. At the surface, we observed a mid-elevational trend in k, which tended to correlate with water availability, cooler temperatures, nutrient availability, and surface-specific bacterial taxa. In sharp contrast, caves showed no elevational impact nor influence of abiotic parameters and bacterial communities on k. Despite this, we found higher levels of S in caves, which were associated mainly with reduced water availability, lower temperatures and cave-specific bacterial taxa, indicating that conditions in caves are strongly linked with carbon storage. Our findings imply that our current perception of terrestrial habitat-based carbon cycling are underestimating the net carbon budget in areas with caves. Disentangling the role of the environment on decomposition in caves is key to fully characterize their roles in nutrient cycling and to understand how increasing anthropogenic pressures will affect fundamental processes in subterranean ecosystems.

Microgreens are emerging specialty crops becoming increasingly popular for their rich nutrient profile and variety of colors, flavors, and textures. The growing medium is a significant key factor in microgreen yield, quality, and sustainability. The widespread use of peat-based media raises questions regarding the environmental sustainability of microgreens production, and new substrates that are more sustainable are required. To this purpose, a study was designed with the objective of comparing eight alternative growing media evaluating their physicochemical properties and effect on yield, mineral profile, and nutritional quality of peas and radish microgreens. Tested substrates included a standard peat and perlite mixture (PP), coconut coir (CC), spent mushroom compost (SMC), organic waste compost (CMP), and 50:50 (v:v) mixes of PP and SMC, PP and CMP, CC and SMC, and CC and CMP. The physicochemical properties widely differed among the alternative substrates tested. SMC had high electrical conductivity and salt concentration, which resulted in poor seed germination. Growing media tested significantly influenced the production and nutritional quality of both microgreen species and variations were modulated by the species. With a 39.8% fresh yield increase or a small yield decrease (-14.9%) in radish and peas, respectively, PP+CMP (50:50, v/v) mix provided microgreens of similar or higher nutritional quality than PP, suggesting the potential of substituting at least in part peat with CMP. Using locally available CMP in mix with PP could reduce the microgreens industry reliance on peat while reducing costs and improving the sustainability of the production of microgreens. Further research is needed to evaluate also the potential economic and environmental benefits of using locally available organic materials like CMP as alternative growing media and peat-substitute to produce microgreens. [ABSTRACT FROM AUTHOR]

Maize is one of the most important cereals in the world. It is a crop demanding in nitrogen. Therefore, alternative sources of fertilization bring agronomic, environmental and economic benefits. The objective of this study was to evaluate the biomass and productivity of maize fertigated with wastewater from swine and fish farming in different dilutions. The soil used is classified as Dystroferric Red Latosol, Cerrado phase, with clayey texture. The experimental design used was randomized blocks in 2 × 4 split plots with three replications. The treatments consisted of two sources of wastewater (fish farming and swine farming) diluted with the recommended dose of wastewater + 0, 25, 50 and 75% of its volume in water. The accumulation of dry mass (leaf, stalk and aerial parts) was evaluated at 30, 60, 90 and 110 days after sowing. The evaluation of yield variables (number of grain rows, number of grains per row, grain sizes, grain dry weight, gran yield and harvest index) occurred at 130 days after sowing. The largest accumulation of dry biomass at the end of the maize cycle and evaluated productivity variables were obtained with the application of swine farming wastewater. Wastewater from fish farming applied via an irrigation system without dilution (0%) is the most suitable for obtaining the productivity of corn grains. The two sources of wastewater have the potential to partially replace mineral nitrogen fertilizer in maize. [ABSTRACT FROM AUTHOR]

Two nutrient–phytoplankton–zooplankton (NZP) models for a closed ecosystem that incorporates a delay in nutrient recycling, obtained using the gamma distribution function with one or two degrees of freedom, are analysed. The models are described by systems of ordinary differential equations of four and five dimensions. The purpose of this study is to investigate how the mean delay of the distribution and the total nutrients affect the stability of the equilibrium solutions. Local stability theory and bifurcation theory are used to determine the long-time dynamics of the models. It is found that both models exhibit comparable qualitative dynamics. There are a maximum of three equilibrium points in each of the two models, and at most one of them is locally asymptotically stable. The change of stability from one equilibrium to another takes place through a transcritical bifurcation. In some hypotheses on the functional response, the nutrient–phytoplankton–zooplankton equilibrium loses stability via a supercritical Hopf bifurcation, causing the apparition of a stable limit cycle. The way in which the results are consistent with prior research and how they extend them is discussed. Finally, various application-related consequences of the results of the theoretical study are deduced. [ABSTRACT FROM AUTHOR]

A total of twenty mixtures of weed, B-Lac and molasses were prepared in order to evaluate an accelerated liquid fertilizer (ALF) based on these plants. A mixture of 85% weed: water (1:1), 10% molasses and 5% BLac showed the best characteristics and was reproduced at a pilot scale. ALF was applied to lettuce using the following treatments: one foliar application per week of 10 mL L-1 (FA1), two foliar applications per week of 10 mL L-1 (FA2), one drench application of 50 mL L-1 every week (DA1), a drench application of 50 mL L-1 every two weeks (DA2) and a control without application (CWA). The variables evaluated were total yield, commercial yield, fresh weight, height, head diameter, percentage of dry matter and the concentration of foliar nitrogen, phosphorus, and potassium. The mixtures in the laboratory and pilot phase were evaluated in a completely randomized design. The field phase was assessed in a completely randomized block design with five treatments and four replications. No significant differences were found between the treatments, except in the percentage of dry matter and potassium content, where FA2 showed the best results (2.35% and 541 mg plant-1, respectively). The highest total yield (26.4 t ha-1) and commercial (24.11 t ha-1) were achieved with DA2; however, the nutritional content was lower than that in the other treatments. Using homolactic fermentation it was possible to recycle weeds and produce ALF, which has potential as a biofertilizer according to its chemical characterization and effects shown on lettuce cultivation. [ABSTRACT FROM AUTHOR]

Volcanic tuffs rich in chabazite zeolites have been extensively examined for their potential to enhance soil properties and increase fertilizer efficiency, both in their natural state and when enriched with nitrogen (N). However, there is a scarcity of data regarding their utilization in acidic sandy soil, particularly when used alongside organic fertilizers. This paper presents the findings of a 50-day laboratory incubation study that investigated the dynamics of N pools in an acidic sandy-loam agricultural soil treated with various N sources. These sources included urea, N-enriched chabazite zeolite tuff, and pelleted composted manure applied at a rate of 170 kg N/ha. Additionally, the N sources were tested in combination with chabazite zeolite tuff mixed into the soil to assess its role as a soil conditioner. The results revealed distinct behaviours among the tested N sources, primarily impacting soil pH and N dynamics. Soil fertilized with manure exhibited slow N mineralization, whereas N-enriched zeolite displayed a more balanced behaviour concerning net NO3−-N production and NH4+-N consumption. Both N-enriched zeolite and urea temporarily altered the soil pH, resembling a “liming” effect, while pelleted manure facilitated a prolonged shift towards neutral pH values. Considering the water adsorption capacity of zeolite minerals, caution is advised when adjusting water content and employing combustion methods to measure soil organic matter in zeolite-treated soil to avoid potential inaccuracies. In summary, N-enriched chabazite zeolite tuff emerged as a valuable N source in acidic sandy-loam soil, offering a promising alternative to synthetic fertilizers and showcasing a sustainable means of N recycling.

Soil function encompasses numerous functions and services the soil provides and can be measured using physical, chemical, and biological characteristics. In any event, research on fertility and biological activity is increasingly being stressed as indices of ecosystem services. Rangeland degradation is one of the world's most widespread land use changes, with serious consequences for soil processes and ecosystem services. The influence of uncontrolled grass cover on soil functioning in semiarid environments is little understood. In the current study, the following seven varieties of grass coverings were studied in a semiarid area of central India: Cenchrus ciliaris (CC), Megathyrsus maximus (MM), Chrysopogon fulvus (CF), Heteropogon contortus (HC), Sehima nervosum (SN), Vetiveria zizanioides (VZ), and Tri-Specific Hybrid (TSH). The carbon accumulation proficiency of TSH, MM, and HC was ~2.23, 2.17, and 2.07 times greater than fallow. The nutrient cycling capacity of grasses was ~1.1 to 1.6 times greater than that of fallow, despite the grasses' depleted macronutrients in the soil. The biological activity under MM and HC was ~1.23 and 1.67 times higher than fallow. Overall soil functionality under TSH and HC was 83 and 25% greater than MM, respectively. These soil functions augment ecosystem services like climate regulation, biomass production, nutrient recycling, water, and airflow. However, more attention should be paid to the management of inputs for greater ecosystem services from this grass cover in semiarid, degraded land.

Human excreta can be used as biofertilizers due to their nutrient and organic matter content. Nevertheless, the behavior of microorganisms should be investigated, as enteric pathogens can accumulate in the soil. Therefore, we evaluated the survival and transport of two enteric bacteria (E. coli and Salmonella enterica) and two enteric virus surrogates (MS2 and ΦX-174 bacteriophages) when applied as contaminants of four biofertilizers on Lactuca sativa production. The study was carried out in lysimeters outdoors with repacked silt loam soil, using a randomized block design (RBD) with six treatments and three replicates. Biofertilizers were urea-treated feces, feces composted with organic waste, stored liquid urine, and struvite and were inoculated at 106–107 cfu/pfu g−1 of E. coli and bacteriophages strains and 107–109 of S. enterica. Soil amended with composted feces exhibited the lowest decimal reductions (T90) for the microorganisms evaluated, with 10.2 days for E. coli, 11.9 days for S. enterica, 22.2 days for MS2, and 3.7 days for ΦX-174. Urea-treated feces temporarily hindered the growth and survival of E. coli and S. enterica in the soil. However, both bacteria were present after one month, while MS2 showed a stable concentration with this biofertilizer. E. coli presented a stable behavior when applied with urine, whereas MS2 was stable with urea-treated feces, urine, and struvite. ΦX-174 and S. enterica were not considered good representatives of most resistant enteric pathogens’ behavior in the soil during food production since they were not detected in leachate and showed a rapid die-off in soil. E. coli leached faster and in higher concentrations than MS2, which presented higher concentrations in deeper soil layers, from 10 to 20 cm. Therefore, using urine, struvite, and urea-treated faces implied a higher chance of infection, as a decimal reduction time was not observed during the 36 days of the experiment. As a result, in short-term cultures, it is recommended that additional hygiene barriers are taken to avoid infection since E. coli and MS2 were still detected at the end of the experiment. An interval of 90 days between fertilizing and harvesting is recommended to prevent pathogen infection. These results are the basis for a quantitative risk assessment of human excreta-based biofertilizers for food production.

A total of twenty mixtures of weed, B-Lac and molasses were prepared in order to evaluate an accelerated liquid fertilizer (ALF) based on these plants. A mixture of 85% weed: water (1:1), 10% molasses and 5% B-Lac showed the best characteristics and was reproduced at a pilot scale. ALF was applied to lettuce using the following treatments: one foliar application per week of 10 mL L-1 (FA1), two foliar applications per week of 10 mL L-1 (FA2), one drench application of 50 mL L-1 every week (DA1), a drench application of 50 mL L-1 every two weeks (DA2) and a control without application (CWA). The variables evaluated were total yield, commercial yield, fresh weight, height, head diameter, percentage of dry matter and the concentration of foliar nitrogen, phosphorus, and potassium. The mixtures in the laboratory and pilot phase were evaluated in a completely randomized design. The field phase was assessed in a completely randomized block design with five treatments and four replications. No significant differences were found between the treatments, except in the percentage of dry matter and potassium content, where FA2 showed the best results (2.35% and 541 mg plant-1, respectively). The highest total yield (26.4 t ha-1) and commercial (24.11 t ha-1) were achieved with DA2; however, the nutritional content was lower than that in the other treatments. Using homolactic fermentation it was possible to recycle weeds and produce ALF, which has potential as a biofertilizer according to its chemical characterization and effects shown on lettuce cultivation.

Urbanization may lead to changes in assemblage and result in shifts in trait distribution from natural habitats to highly urbanized habitats. The shift in functional traits can affect ecosystem functions in urban areas. This study explored the foraging period of ants over 72 h and determined the relationship between the behavioral, morphological, and physiological traits of local foragers ants and environmental conditions in urban and forest sites. In addition, this study examined the ants’ ecosystem functions and compared it with that of their forest counterparts. Our results revealed that the foraging period of ants (i.e., Cardiocondyla sp.1, Monomorium chinense, Paratrechina longicornis, Pheidole megacephala, and Solenopsis sp.1) in urban areas peaked between 0900 and 1500 and that of some ants (i.e., Carebara diversa, P. megacephala, Pheidole fervens, Plagiolepis longwang, and Nylanderia sp.1) in forest areas was constant over time. For urban ants, a weak correlation was observed between foraging period and body size traits (i.e., Weber’s length and head width). This finding indicates that the major factor underlying the change in the foraging period might not be related to body size. Rather, the change may be attributed to synchronization between food availability and human activity (waste disposal; i.e., between 0900 and 1800). The shift in the functional traits of ants affects ecosystem functions in urban areas. In urban areas, although only one predatory ant species (P. megacephala) was sampled, its activity density was high. Most of these individuals were active during the daytime, indicating that the predatory behavior of ants in the novel urban environment has decreased temporally and is limited to the daytime. Urban ants tended to choose smaller food particles, whereas forest ants preferred larger food particles and had a twofold higher food removal rate.

Microgreens are emerging specialty crops becoming increasingly popular for their rich nutrient profile and variety of colors, flavors, and textures. The growing medium is a significant key factor in microgreen yield, quality, and sustainability. The widespread use of peat-based media raises questions regarding the environmental sustainability of microgreens production, and new substrates that are more sustainable are required. To this purpose, a study was designed with the objective of comparing eight alternative growing media evaluating their physicochemical properties and effect on yield, mineral profile, and nutritional quality of peas and radish microgreens. Tested substrates included a standard peat and perlite mixture (PP), coconut coir (CC), spent mushroom compost (SMC), organic waste compost (CMP), and 50:50 (v:v) mixes of PP and SMC, PP and CMP, CC and SMC, and CC and CMP. The physicochemical properties widely differed among the alternative substrates tested. SMC had high electrical conductivity and salt concentration, which resulted in poor seed germination. Growing media tested significantly influenced the production and nutritional quality of both microgreen species and variations were modulated by the species. With a 39.8% fresh yield increase or a small yield decrease (-14.9%) in radish and peas, respectively, PP+CMP (50:50, v/v) mix provided microgreens of similar or higher nutritional quality than PP, suggesting the potential of substituting at least in part peat with CMP. Using locally available CMP in mix with PP could reduce the microgreens industry reliance on peat while reducing costs and improving the sustainability of the production of microgreens. Further research is needed to evaluate also the potential economic and environmental benefits of using locally available organic materials like CMP as alternative growing media and peat-substitute to produce microgreens.

Sustainable food production has become increasingly important. Soilless cultivation systems offer several advantages, such as water and nutrient use efficiency, and can be implemented where traditional agriculture is impossible. Bioponic systems use locally or regionally available nutrient sources from organic waste streams (either fluid or solid) and can thus contribute to closing nutrient cycles locally. Bioponics harnesses the metabolic processes of microorganisms which release nutrients from organic matter. This study aimed to set up a bioponic system, by using biogas digestate concentrate and biochar as nutrient sources, and promoting nutrient release from the organic sources by including a biofilter in the system. The development of water quality, plant growth, and quality was monitored extensively. In addition, the influence of either the fungal biocontrol agent Trichoderma atrobrunneum or UV-C treatment of the nutrient solution on plant health and growth was investigated. Three cultivation cycles with Lactuca sativa ("HAWKING" Salanova®) in bioponic (BP), hydroponic (HP), and soil (SO) cultivation were performed. The study showed that healthy lettuces could be produced in BP systems, using a biogas digestate concentrate and biochar as nutrient sources, despite salt accumulation in the nutrient solution. In plant sap analyses, lettuces cultivated in BP systems contained less nitrate but more ammonium and chloride. The yield of the lettuces grown in the BP systems was intermediate, compared to the HP and the SO. The fungus, T. atrobrunneum, strain, T720, survived in soil and soilless cultivation systems. Compared to the HP and the SO systems, the shoot height of lettuces grown in the BP system, with the application of Trichoderma, was significantly increased. In SO systems with Trichoderma application, a significantly higher chlorophyll and flavonoid content, but significantly lower shoot height was observed. The fresh weight of lettuce roots was significantly higher in HP systems with Trichoderma treatment. Cultivating plants by using organic waste streams requires commitment and experience from producers. In BP systems, a biofilter (either within the system or externally, to increase nutrient levels) can help to rapidly convert the ammonium-rich fertilizer to plant-available nutrients. Unlike conventional HP systems, in BP systems, nutrients are released slowly over time, requiring close monitoring and adjustments. In conclusion, healthy lettuces for human consumption can be produced in BP systems, and the application of the biocontrol agent used has some beneficial influence on plant growth. [ABSTRACT FROM AUTHOR]

The sustainable management of forest plantations by keeping the harvest residues on site improves the soil's chemical, physical and biological properties while constituting an important nutrient reserve. Our objectives were: (a) to identify and quantify the characteristics of Eucalyptus dunnii, Eucalyptus grandis and Eucalyptus globulus that affect the decomposition rates of harvest residues, as well as indicators that can explain the process and (b) to quantify the potential recycling of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) to the soil from residue decomposition and the quantitative and qualitative differences between the species. We analyzed the information of five commercial plantations of Uruguay. At the harvest, the biomass of leaves, thin and thick branches, bark and their respective N, P, K, Ca and Mg contents were quantified. At each site, bags with samples of the different residues were left to decompose and were periodically collected throughout 24 months. Eucalyptus dunnii presented the largest amounts of residues of all parts. The decomposition rates of the different residues depended on their chemical constitution, part size and the species. Eucalyptus dunnii leaves showed the shortest half-life (0.94 years), while the bark of the same species presented the longest (5.62 years). Total nitrogen and carbon (total and soluble) contents, which can be easily determined, emerged as good predictors for half-life estimation. The release patterns of nutrients depended more on their dynamics in the plant and their parts than on the species itself. The results highlight the importance of nutrient recycling to ensure the sustainability of the productive system in the medium and long term. [ABSTRACT FROM AUTHOR]

In order to further close nutrient cycles of aquaponic systems, it could be possible to integrate a third trophic level in the form of insect larvae production (i.e., black soldier fly larvae) to recycle internal waste streams into valuable nutrients. This would present opportunities to formulate sustainable circular aquafeeds that combine these internally available nutrients with complementary external raw materials. The ingredient composition of feeds for such circular multitrophic food production systems (CMFS) may affect fish performance as well as excretion of important dissolved plant nutrients such as N, P and K. Hence, fish meal from catfish processing (CM) as base ingredient was combined with variable levels of poultry by-product meal (PM) and black soldier fly larvae meal (BSFM) into three marine-ingredient-free experimental diets corresponding to hypothetical production scenarios of a CMFS that aims to integrate aquaponics with insect larvae production. These experimental diets and a commercial diet (COM) were compared using isonitrogenous and isolipidic formulations. They were fed to African catfish (Clarias gariepinus) in recirculating aquaculture systems (RAS) and evaluated concerning growth performance and nutrient excretion. All diets resulted in similar total inorganic nitrogen (TIN) excretion, whereas the increase of dietary PM inclusion from 0% (BSF diet) to 20% (MIX diet) and to 41% (PM diet) and concomitant reduction of BSFM inclusion led to increasingly higher soluble reactive phosphorus (SRP) excretion per unit of feed compared to the COM diet. While the PM diet enabled the best growth and feed conversion performance, the MIX and especially the BSF diet produced more similar performance to the COM diet, which generated the highest dissolved K excretion. The MIX and the PM diet resulted in the highest Ca and P, yet lower N content in the fish feces. Results indicate that combining CM with elevated levels of PM in the diet of African catfish could improve growth performance and reduce the need for P fertilization in aquaponics when compared to industrial diets optimized for low environmental impact. Findings are discussed regarding their implications for CMFS and aquaponic feed formulation. [ABSTRACT FROM AUTHOR]

This study focuses on the feasibility of the dry anaerobic digestion of solid agricultural biomass for efficient renewable-energy production and nutrient recycling. Methane production and the amount of nitrogen in the digestates were measured in pilot- and farm-scale leach-bed reactors. In the pilot scale, with a digestion time of 133 days, the methane production of a mixture of whole crop fava bean and horse manure corresponded to 94% and 116%, respectively, of the methane potentials of the solid substrates. The mono-digestion of fava beans resulted in relatively low methane production (production/potential ratios of 59% and 57%). In two full-scale experiments, the methane production of mixtures of clover-grass silage, chicken manure, and horse manure corresponded to 108% and 100% of their respective methane potentials with digestion times of 117 and 185 days. In co-digestion, the production/potential ratios were similar in the pilot and farm experiments. High nitrogen loss was observed in the farm scale when the digestate was stored in a stack covered with a tarpaulin during summertime. Thus, although the technology seems promising, attention needs to be paid to management practices to minimise nitrogen losses and greenhouse gas emissions. [ABSTRACT FROM AUTHOR]

Urban areas can be differently anthropized; often, high-density populations lead to higher amounts of pollution. Nowadays, ornamental plants can represent important living components of urban areas, and if appropriate species are used, they can provide important ecosystem services. The relationships between green infrastructures and ecosystem services have been recognized for a long time, but the role of ornamental plant species has not been studied as much. In this frame, the different ecosystem services of ornamental plants, i.e., provisioning (e.g., food, air, and water cleaning), regulating (e.g., rain water, climate, nutrient recycling, pollination, and the formation of fertile soils), and cultural (e.g., recreation opportunities or the inspiration we draw from nature) will be critically analyzed to select the most suitable ornamental plant species able to assure the better performance. The action mechanisms will also be analyzed and discussed to individuate the best ideotypes of plant species able to better assure water purification, air quality, space for recreation, climate mitigation and adaptation, human wellbeing, and health. This information is suitable to ensure that the protection, restoration, creation, and enhancement of green infrastructure become integral parts of urban spatial planning and territorial development.

Integrating a combination of organic matter management (OMM) practices can increase soil fertility, biomass, and nutrient recycling, but evidence of this potential is limited. This study tested the impact of integrating a combination of OMM practices on soil fertility, biomass, and nutrient recycling on smallholder farms. Following a randomised complete block design, a four-season experiment was conducted in 2018-2019 on 10 farms. The treatments (T) included T1: cowpea-maize-bean-maize rotation; T2: cowpea-maize-bean-maize rotation + farmyard manure; T3: Faidherbia albida alleys + cowpea-maize-bean-maize rotation; T4: F. albida alleys + cowpea-maize-bean-maize rotation + farmyard manure; and T5 (control): maize monocrop with diammonium phosphate application at 50 kg/ha application rate. T1-T4 are the OMM practices. The maize in T2-T4 was undersown with Mucuna pruriens. Soil fertility parameters (i.e. pH, water holding capacity, nitrogen, phosphorus, and potassium), biomass, and nutrients in the biomass were determined. There were no differences in soil fertility parameters among all treatments (P > 0.05). From the second to the fourth season, biomass was consistently higher under T3 and T4 than in other treatments. Moreover, the nutrients in biomass were higher in T3 and T4 than in other treatments, an indicator that OMM practices with alley crops can increase nutrient recycling.

Purpose Agronomic and environmental reasons force farmers to know the total P concentration of composted cattle manure. Laser-Induced Breakdown Spectroscopy seems proper to obtain such information. For logistic reasons (carriage, storage, field application, etc.), a dry matter characterization is also needed.Method Thirty samples of feedlot compost at different stages of stability and maturity were studied. Samples were dried at 50°C for dry matter characterization. As a reference method to determine total P concentration, wet digestion and colorimetry were employed. The area of the P I line emission obtained by laser-induced ablation of the samples was measured to estimate the total P concentration. Randomized calibrations through a modified version of the Kennard-Stone algorithm based on the Mahalanobis distance were performed.Results Dry matter varied from 40% to 90%, and no pattern was found related to compost origin, maturity, or stability. The total P concentration of the studied compost ranged from 1800 ppm up to 11200 ppm. Almost 80% of the calibration fittings have an R2 ≥ 0.895. The mean validation error was less than 22% for about 80% of the calibrations, with a mean prediction error bound to 40%. Discarding outliers, the errors were reduced to 19% and 30%, respectively.Conclusion Water content must be considered in addition to other characterizations due to logistic implications. Calibrations with a 30 percent of prediction error were achieved, which seems enough as a first approximation to predict the total P content in compost for utilization in farms to recycle nutrients.

Microalgae are capable of assimilating nutrients from wastewater (WW), producing clean water and biomass rich in bioactive compounds that need to be recovered from inside the microalgal cell. This work investigated subcritical water (SW) extraction to collect high-value compounds from the microalga Tetradesmus obliquus after treating poultry WW. The treatment efficiency was evaluated in terms of total Kjeldahl nitrogen (TKN), phosphate, chemical oxygen demand (COD) and metals. T. obliquus was able to remove 77% TKN, 50% phosphate, 84% COD, and metals (48–89%) within legislation values. SW extraction was performed at 170 °C and 30 bar for 10 min. SW allowed the extraction of total phenols (1.073 mg GAE/mL extract) and total flavonoids (0.111 mg CAT/mL extract) with high antioxidant activity (IC50 value, 7.18 µg/mL). The microalga was shown to be a source of organic compounds of commercial value (e.g., squalene). Finally, the SW conditions allowed the removal of pathogens and metals in the extracts and residues to values in accordance with legislation, assuring their safety for feed or agriculture applications. [ABSTRACT FROM AUTHOR]

Leaf decay in seagrasses is enhanced in some seasons since large green senescent beach-cast seagrass leaves are frequently recorded during autumn and winter seasons. Here, we explore if senescence is operating in seagrass leaf decay or if hydrodynamic stress is responsible for the seasonal leaf abscission. A seasonal study on the temperate seagrass Cymodocea nodosa was carried out in four locations with contrasting hydrodynamic regimes. The morphological, biomechanical and material properties of C. nodosa were measured. The force required to break the ligule was always lower than that required to break the blade. This could be considered an adaptive strategy to reduce acute drag forces and thus lessen the chance of plant uprooting. The absolute force needed to dislodge the blade at the ligule level varied with season and location, with the lowest forces recorded in autumn. This may indicate that senescence is operating in this species. On the other hand, the minimum estimated failure velocities for leaf abscission were also recorded in autumn. Consequently, this may cause the premature shedding of leaves in this season before the senescence process has finished and can probably explain the occurrence of green beach-cast seagrass leaves usually found during autumn and winter. [ABSTRACT FROM AUTHOR]

IntroductionSustainable growth of the salmon aquaculture industry is highly dependent on the availability of new feed resources as well as improved management and utilization of waste streams from production. Polychaetes are capable of recapturing and recycling valuable biomolecules contained in aquaculture sludge and at the same time constitute a possible resource for aquafeeds.Material and methodsIn this study, the potential of Hediste diversicolor (OF Müller, 1776) to recover nutrients and energy contained aquaculture sludge was evaluated. Hereby, the effect of two different diets, smolt and post-smolt sludge, and different feed levels on polychaete growth, and biochemical and elemental composition was assessed.Results and discussionSurvival ranged from 80-90%, independent of treatment. Specific growth rates at the highest feed levels were significantly higher than at the lowest feed levels and growth was not affected by the type of diet. Similarly, total lipid and total fatty acid content of polychaetes were positively correlated with feed level while the type of diet had a limited effect. Fatty acid composition of polychaetes reflected feed levels: in both diet groups, polychaetes at lower feed levels showed a higher percentage of saturated fatty acids; monounsaturated fatty acids increased with increased feed supply for smolt sludge-fed group and polychaetes fed post-smolt sludge showed increased polyunsaturated fatty acid content with increasing feed levels. Neither diet nor feed levels affected protein content and amino acid composition of polychaetes. In conclusion, H. diversicolor could be successfully cultivated on both smolt and post-smolt sludge and was rich in proteins and lipids as well as essential amino and fatty acids. The species can be considered a promising candidate for recycling valuable nutrients from different types of side streams salmon aquaculture.

The use of liquid waste as a feedstock for cultivation of microalgae can reduce water and nutrient costs and can also be used to treat wastewater with simultaneous production of biomass and valuable products. This study applied strategies to treat diluted anaerobic digester effluent (ADE) as a residue of biogas reactors with moderate (87 ± 0.6 mg L−1; 10% ADE) and elevated NH4+-N levels (175 ± 1.1 mg L−1; 20% ADE). The effect of ADE dilution on the acclimatization of various microalgae was studied based on the analysis of the growth and productivity of the tested green algae. Two species of the genus Chlorella showed robust growth in the 10–20% ADE (with a maximum total weight of 3.26 ± 0.18 g L−1 for C. vulgaris and 2.81 ± 0.10 g L−1 for C. sorokiniana). The use of 10% ADE made it possible to cultivate the strains of the family Scenedesmaceae more effectively than the use of 20% ADE. The growth of Neochloris sp. in ADE was the lowest compared to other microalgal strains. The results of this study demonstrated the feasibility of introducing individual green microalgae into the processes of nutrient recovery from ADE to obtain biomass with a high protein content. [ABSTRACT FROM AUTHOR]

Urban areas can be differently anthropized; often, high-density populations lead to higher amounts of pollution. Nowadays, ornamental plants can represent important living components of urban areas, and if appropriate species are used, they can provide important ecosystem services. The relationships between green infrastructures and ecosystem services have been recognized for a long time, but the role of ornamental plant species has not been studied as much. In this frame, the different ecosystem services of ornamental plants, i.e., provisioning (e.g., food, air, and water cleaning), regulating (e.g., rain water, climate, nutrient recycling, pollination, and the formation of fertile soils), and cultural (e.g., recreation opportunities or the inspiration we draw from nature) will be critically analyzed to select the most suitable ornamental plant species able to assure the better performance. The action mechanisms will also be analyzed and discussed to individuate the best ideotypes of plant species able to better assure water purification, air quality, space for recreation, climate mitigation and adaptation, human wellbeing, and health. This information is suitable to ensure that the protection, restoration, creation, and enhancement of green infrastructure become integral parts of urban spatial planning and territorial development. [ABSTRACT FROM AUTHOR]

Concern that depletion of fertilizer feedstocks, which are a finite mineral resource, threatens agricultural sustainability has driven the exploration of sustainable methods of soil fertilization. Given that microalgae, which are unicellular photosynthetic organisms, can take up nutrients efficiently from water systems, their application in a biological wastewater purification system followed by the use of their biomass as a fertilizer alternative has attracted attention. Such applications of microalgae would contribute to the accelerated recycling of nutrients from wastewater to farmland. Many previous reports have provided information on the physiological characteristics of microalgae that support their utility. In this review, we focus on recent achievements of studies on microalgal physiology and relevant applications and outline the prospects for the contribution of microalgae to the establishment of sustainable agricultural practices. [ABSTRACT FROM AUTHOR]

In aquaponics and circular multitrophic food production systems, dietary protein source, as well as fish species choice, particularly in cases of different nutritional physiology, could be factors affecting excreted nutrient profiles. Accordingly, growth performance, dissolved nutrient accumulation and feces nutrient profiles were evaluated for African catfish (Clarias gariepinus) reared in recirculating aquaculture systems (RAS) and fed single protein source diets based on black soldier fly larvae meal (BSF), poultry by-product meal (PM), poultry blood meal (PBM) and fish meal (FM) and the results were compared to previous findings for Nile tilapia (Oreochromis niloticus). All diets resulted in significantly different growth performances of African catfish, with FM producing the best growth performance, followed by PM, BSF and PBM. PM resulted in the highest soluble reactive phosphorus concentrations (SRP) in the RAS water; whereas, BSF resulted in the highest K, Mg and Cu concentrations. The highest feces nutrient density was recorded for PBM; whereas, FM and PM yielded the lowest feces nutrient density. Comparing African catfish to Nile tilapia revealed that the former showed significantly better growth performance with FM and PM, however, significantly weaker performance with BSF. Although dissolved K accumulation was similar between species across diets, significant differences were recorded for total inorganic nitrogen and SRP production per unit of feed for individual diets. Despite similar feces nutrient profiles, African catfish produce significantly less feces dry matter per unit of feed for each diet compared to Nile tilapia. Findings are discussed regarding their implications for aquafeed development in the context of circular multitrophic food production systems. [ABSTRACT FROM AUTHOR]

A stochastic nutrient–phytoplankton–zooplankton model with instantaneous nutrient recycling is proposed and analyzed in this paper. When the nutrient uptake function and the grazing function are linear and the ingested phytoplankton is completely absorbed by the zooplankton, we establish two stochastic thresholds R 0 S and R 1 S , which completely determine the persistence and extinction of the plankton. That is, if R 0 S < 1 , both the phytoplankton and the zooplankton eventually are eliminated; if R 0 S > 1 and R 1 S < 1 , the phytoplankton is persistent in mean but the zooplankton is extinct; while for R 1 S > 1 , the entire system is persistent in mean. Furthermore, sufficient criteria for the existence of ergodic stationary distribution of the model are obtained and the persistent levels of the plankton are estimated. Numeric simulations are carried out to illustrate the theoretical results and to conclude our study. Our results suggest that environmental noise may cause the local bloom of phytoplankton, which surprisingly can be used to explain the formation of algal blooms to some extent. Moreover, we find that the nonlinear nutrient uptake function and grazing function may take credit for the periodic succession of blooms regardless of whether they are in the absence or presence of the environmental noises. [ABSTRACT FROM AUTHOR]

Mass cultivation of high-value aromatic herbs such as Vietnamese coriander and Persicaria odorata required specific soil, nutrients, and irrigation, mostly found in the limited natural wetland. This study aimed to evaluate the capacity of P. odorata at different densities in nutrient removal and the growth performance of African catfish, Clarias gariepinus in aquaponic systems. P. odorata was cultivated for 40 d with less than 10% water exchange. The effects of increasing crop densities, from zero plants for the control, 0.035 ± 0.003 kg/m2 in Treatment 1, 0.029 ± 0.002 kg/m2 in Treatment 2, and 0.021 ± 0.003 kg/m2 in Treatment 3, were tested on the growth performance of C. gariepinus with an initial density of 3.00 ± 0.50 kg/m3. The specific growth rate (S G R), daily growth rate of fish ( D G R f), and survival rate (S R) of the C. gariepinus were monitored. Nutrient removal, daily growth rate of plant (D G R p) , relative growth rate (R G R), and the sum of leaf number (Ʃ n) of the P. odorata plant were also recorded. It was found that nutrient removal percentage significantly increased with the presence of P. odorata at different densities. The growth performance of C. gariepinus was also affected by P. odorata density in each treatment. However, no significant difference was observed in the D G R p and R G R of the P. odorata (p > 0.05), except for Ʃ n values. Treatment 1 had the highest Ʃ n number compared to Treatment 2 and Treatment 3, showing a significant difference (p < 0.05). This study demonstrates that the presence of P. odorata significantly contributes to lower nutrient concentrations, supporting the fundamental idea that plants improve water quality in aquaponic systems. [Display omitted] • P. odorata needs a large natural wetland area for cultivation. • Aquaponics offers an alternative artificial wetland for cultivation. • Various P. odorata densities were tested to optimize growth performance. • P. odorata in aquaponics grew three times faster than in nature. • Less than 10% water exchange promotes zero-waste. [ABSTRACT FROM AUTHOR]

Incorporating a variety of microalgae into wastewater treatment is considered an economically viable and environmentally sound strategy. The present work assessed the growth characteristics of Chlorella sorokiniana during cultivation in balanced synthetic media and domestic wastewater. Increasing the NH4+–N concentration to 360 mg L−1 and adding extra PO43−–P and SO42−–S (up to 80 and 36 mg L−1, respectively) contributed to an increase in the total biomass levels (5.7–5.9 g L−1) during the cultivation of C. sorokiniana in synthetic media. Under these conditions, the maximum concentrations of chlorophylls and carotenoids were 180 ± 7.5 and 26 ± 1.4 mg L−1, respectively. Furthermore, when studying three types of domestic wastewaters, it was noted that only one wastewater contributed to the productive growth of C. sorokiniana, but all wastewaters stimulated an increased accumulation of protein. Finally, the alga, when growing in optimal unsterilized wastewater, showed a maximum specific growth rate of 0.73 day−1, a biomass productivity of 0.21 g L−1 day−1, and 100% NH4+–N removal. These results demonstrate that the tested alga actively adapts to changes in the composition of the growth medium and accumulates high levels of protein in systems with poor-quality water.