The mechanisms of pH regulation on promoting volatile fatty acids production from kitchen waste.

The anaerobic acid production experiments were conducted with the pretreated kitchen waste under pH adjustment. The results showed that pH 8 was considered to be the most suitable condition for acid production, especially for the formation of acetic acid and propionic acid. The average value of total volatile fatty acid at pH 8 was 8814 mg COD/L, 1.5 times of that under blank condition. The average yield of acetic acid and propionic acid was 3302 mg COD/L and 2891 mg COD/L, respectively. The activities of key functional enzymes such as phosphotransacetylase, acetokinase, oxaloacetate transcarboxylase and succinyl-coA transferase were all enhanced. To further explore the regulatory mechanisms within the system, the distribution of microorganisms at different levels in the fermentation system was obtained by microbial sequencing, results indicating that the relative abundances of Clostridiales, Bacteroidales, Chloroflexi, Clostridium, Bacteroidetes and Propionibacteriales, which were great contributors for the hydrolysis and acidification, increased rapidly at pH 8 compared with the blank group. Besides, the proportion of genes encoding key enzymes was generally increased, which further verified the mechanism of hydrolytic acidification and acetic acid production of organic matter under pH regulation.

Soil colloids can significantly enhance spreading of polybromodiphenyl ethers in groundwater by serving as an effective carrier.

Polybromodiphenyl ethers (PBDEs), the widely used flame retardants, are common contaminants in surface soils at e-waste recycling sites. The association of PBDEs with soil colloids has been observed, indicating the potential risk to groundwater due to colloid-facilitated transport. However, the extent to which soil colloids may enhance the spreading of PBDEs in groundwater is largely unknown. Herein, we report the co-transport of decabromodiphenyl ester (BDE-209) and soil colloids in saturated porous media. The colloids released from a soil sample collected at an e-waste recycling site in Tianjin, China, contain high concentration of PBDEs, with BDE-209 being the most abundant conger (320 ± 30 mg/kg). The colloids exhibit relatively high mobility in saturated sand columns, under conditions commonly observed in groundwater environments. Notably, under all the tested conditions (i.e., varying flow velocity, pH, ionic species and ionic strength), the mass of eluted BDE-209 correlates linearly with that of eluted soil colloids, even though the mobility of the colloids varies markedly depending on the specific hydrodynamic and solution chemistry conditions involved. Additionally, the mass of BDE-209 retained in the columns also correlates strongly with the mass of retained colloids. Apparently, the PBDEs remain bound to soil colloids during transport in porous media. Findings in this study indicate that soil colloids may significantly promote the transport of PBDEs in groundwater by serving as an effective carrier. This might be the reason why the highly insoluble and adsorptive PBDEs are found in groundwater at some PBDE-contaminated sites.

Inhibition of jarosite heterogeneous crystallization on anglesite via in-situ formation of competitive substrate.

Heterogeneous crystallization is a common occurrence during the formation of solid wastes. It leads to the encapsulation of valuable/hazardous metals within the primary phase, presenting significant challenges for waste treatment and metal recovery. Herein, we proposed a novel method involving the in-situ formation of a competitive substrate during the precipitation of jarosite waste, which is an essential process for removing iron in zinc hydrometallurgy. We observed that the in-situ-formed competitive substrate effectively inhibits the heterogeneous crystallization of jarosite on the surface of anglesite, a lead-rich phase present in the jarosite waste. As a result, the iron content on the anglesite surface decreases from 34.8% to 1.65%. The competitive substrate was identified as schwertmannite, characterized by its loose structure and large surface area. Furthermore, we have elucidated a novel mechanism underlying this inhibition of heterogeneous crystallization, which involves the local supersaturation of jarosite caused by the release of ferric and sulfate ions from the competitive substrate. The local supersaturation promotes the preferential heterogeneous crystallization of jarosite on the competitive substrate. Interestingly, during the formation of jarosite, the competitive substrate gradually vanished through a dissolution-recrystallization process following the Ostwald rule, where a metastable phase slowly transitions to a stable phase. This effectively precluded the introduction of impurities and reduced waste volume. The goal of this study is to provide fresh insights into the mechanism of heterogeneous crystallization control, and to offer practical crystallization strategies conducive to metal separation and recovery from solid waste in industries.

Use of waste frying oil and coconut pulp for the production, isolation, and characterization of a new lipase from Moesziomyces aphidis.

Lipases comprise the third most commercialized group of enzymes worldwide and those of microbial origin are sought for their multiple advantages. Agro-industrial waste can be an alternative culture medium for producing lipases, reducing production costs and the improper disposal of waste frying oil (WFO). This study aimed to produce yeast lipases through submerged fermentation (SF) using domestic edible oil waste as inducer and alternative culture medium. The optimal culture conditions, most effective inducer, and purification method for a new lipase from Moesziomyces aphidis BRT57 were identified. Yeast was cultured in medium containing green coconut pulp and WFO waste for 72 h. The maximum production of lipases in SF occurred in a culture medium containing WFO and yeast extract at 48 and 72 h of incubation, with enzyme activities of 8.88 and 11.39 U mL-1, respectively. The lipase was isolated through ultrafiltration followed by size exclusion chromatography, achieving a 50.46 % recovery rate. To the best of our knowledge, this is the first study to report the production and purification of lipases from M. aphidis, demonstrating the value of frying oil as inducer and alternative medium for SF, contributing to the production of fatty acids for biodiesel from food waste.

Emerging deep eutectic solvents for food waste valorization to achieve sustainable development goals: Bioactive extractions and food applications.

Food waste, accounting for about one-third of the total global food resources wasted each year, is a substantial challenge to global sustainability, contributing to adverse environmental impacts. The utilization of food waste as a valuable source for bioactive extraction can be facilitated through the application of DES (Deep Eutectic Solvents). Acknowledging the significant need to tackle this issue, the United Nations integrated food waste management into its Sustainable Development Goals, hence, the present review explores the role of DES in bioactive compounds extraction from food waste. Various extraction processes using the DES system are thoroughly studied and the application of bioactive components as antioxidants, antimicrobials, flavourings, nutraceuticals, functional ingredients, additives, and preservatives is investigated. Most importantly, regulatory considerations and safety aspects of DES in food applications are discussed in-depth along with consumer perception and acceptance of DES in the food sector. The key hypothesis of the review is to evaluate emerging DES systems for their efficiency in bioactive extraction technologies and various food applications. Overall, this review provides a comprehensive understanding of utilizing DES for synthesizing valuable food waste-derived bioactive components, offering a sustainable approach to waste management and the development of high-value products.

Atlantic salmon (Salmo salar) waste as a unique source of biofunctional protein hydrolysates: Emerging productions, promising applications, and challenges mitigation.

The Atlantic salmon is an extremely popular fish for its nutritional value and unique taste among several fish species. Researchers are focusing on the utilization of Atlantic salmon waste for generating protein hydrolysates rich in peptides and amino acids and investigating their health benefits. Several technological approaches, including enzymatic, chemical, and the recently developed subcritical water hydrolysis, are currently used for the production of Atlantic salmon waste protein hydrolysates. Hydrolyzing various wastes, e.g., heads, bones, skin, viscera, and trimmings, possessing antioxidant, blood pressure regulatory, antidiabetic, and anti-inflammatory properties, resulting in applications in human foods and nutraceuticals, animal farming, pharmaceuticals, cell culture, and cosmetics industries. Furthermore, future applications, constraints several challenges associated with industrial hydrolysate production, including sensory, safety, and economic constraints, which could be overcome by suggested techno processing measures. Further studies are recommended for developing large-scale, commercially viable production methods, focusing on eradicating sensory constraints and facilitating large-scale application.

Achieving high-durability aqueous Zn-ion batteries enabled by reanimating inactive Zn on Zn anodes.

The heavy by-products generated on Zn anode surface decrease the active surface of Zn anodes and thus induce uneven Zn deposition, seriously reducing the service life of aqueous Zn-ion batteries (AZIBs). Herein, we propose an elimination strategy enabled by the coordination chemistry to dissolve the main by-products (Zn4SO4(OH)6·xH2O). Urea as a proof-of-concept has been applied as the reactivator in the electrolyte to catalytically produce highly active NH3 on the surface of the by-products. Then the NH3 can powerfully coordinate with the Zn2+ ion in the by-products to form the soluble complex [Zn(NH3)4]2+. Consequently, the proposed electrolyte can not only lead to the timely decomposition of the by-products to prevent the Zn anode from inactivation during cycling, but also repair the waste Zn anodes for reutilization. The action mechanism has been systematically demonstrated via theoretical simulation and experimental study. As a result, the high durability with ultrahigh cumulative capacity of 10,600 mAh cm-2 for the Zn||Zn symmetric cell has been achieved at 40 mA cm-2. Particularly, the dead Zn||Zn symmetric cells and Zn||LiFePO4 full cells have been successfully reactivated. This study lights a new route to extend the cell lifespan and reuse waste Zn-ion batteries.

Preferential association of PBDEs and PAHs with mineral particles vs. dissolved organic carbon: Implications for groundwater contamination at e-waste sites.

Polybrominated biphenyl ethers (PBDEs) and polycyclic aromatic hydrocarbons (PAHs) are commonly detected contaminants at e-waste recycling sites. Against the conventional wisdom that PBDEs and PAHs are highly immobile and persist primarily in shallow surface soils, increasing evidence shows that these compounds can leach into the groundwater. Herein, we compare the leachabilities of PBDEs vs. PAHs from contaminated soils collected at an e-waste recycling site in Tianjin, China. Considerable amounts of BDE-209 (0.3-2 ng/L) and phenanthrene (42-106 ng/L), the most abundant PBDE and PAH at the site, are detected in the effluents of columns packed with contaminated soils, with the specific concentrations varying with hydrodynamic and solution chemistry conditions. Interestingly, the leaching potential of BDE-209 appears to be closely related to the release of colloidal mineral particles, whereas the leachability of phenanthrene correlates well with the concentration of dissolved organic carbon in the effluent, but showing essentially no correlation with the concentration of mineral particles. The surprisingly different trends of the leachability observed between BDE-209 and phenanthrene is counterintuitive, as PBDEs and PAHs often co-exist at e-waste recycling sites (particularly at the sites wherein incineration is being practiced) and share many similarities in terms of physicochemical properties. One possible explanation is that due to its extremely low solubility, BDE-209 predominantly exists in free-phase (i.e., as solid (nano)particles), whereas the more soluble phenanthrene is mainly sorbed to soil organic matter. Findings in this study underscore the need to better understand the mobility of highly hydrophobic organic contaminants at contaminated sites for improved risk management.

Dataset on thermal conductivity of composted olive cake (COC).

Thermal properties play a critical role in the compost used as a soil amendment for different agricultural applications especially for green roof buildings. Despite this importance, there remains insufficient information on thermal conductivity of composted olive cake (COC), K, and how it is influenced by bulk its density and water content. This shows how thermal conductivity (K) is affected by these two parameters and the potential use of COC as cheap padding in geothermal heat storage and green roof building applications. Thermal conductivities of 30 samples of (COC) were measured experimentally at different moisture contents and bulk densities using a hot wire technique. The results revealed that thermal conductivity exhibits a linear increase as both bulk density and water content increased. It increased from 0.10 to 0.60 W/(m K) at saturation levels ranging from dry to 90 %. The highest thermal conductivity of 0.60 W/m K was revealed at a water content of 90 %. Therefore, (COC) might be used as an inexpensive padding in geothermal heat storage applications and as an eco-friendly insulation pad in green- roof buildings, leading to passive energy savings. Overall, the study provides important insights into the thermal properties of COC and its potential as a sustainable insulation material.

Quantifying the relative importance of agricultural land use as a predictor of catchment nitrogen and phosphorus concentrations.

Agriculture is a major source of nitrogen (N) and phosphorus (P) in freshwater ecosystems, and different management strategies exist to reduce farmland nutrient losses and thus mitigate freshwater eutrophication. The importance of agricultural sources of N and P as drivers of water quality is known to vary spatially, but quantification of the relative importance of the nutrient sources shaping this variability remains challenging, especially with reference to inputs from waste water treatment works. Addressing this knowledge gap is key for targeting management strategies to where they are likely to have the greatest effect. To advance our understanding in this area, this study assesses the impact of population density as a driver of the relative importance of agricultural land use for predicting mean Total Oxidised Nitrogen (TON) and Reactive Phosphorus (RP) concentrations in rivers in England, using two different data-driven, statistical approaches: a generalised linear model and random forest. Our results show that agricultural N and P sources dominate in catchments with low population density, where stream water concentrations are lower and waste water treatment works are numerous, but smaller in terms of the population equivalent served. Agricultural N and P sources are not important predictors of N and P in catchments with high population density, where contributions from waste water treatment works dominate. These results require cautious interpretation, as model validation outcomes show that high TON and RP concentrations are consistently underpredicted. Altogether, our results suggest that the relative contribution of agricultural sources may be overestimated in densely populated catchments, relative to point sources from waste water treatment works, and that management strategies to reduce the contribution of agriculture to N and P in rivers may be better targeted towards catchments with lower population density, as this is where agricultural land use is the primary source of N and P.

Assessing determinants and readiness for willingness-to-pay (WTP) for unit-based pay-as-you-throw (PAYT) waste tariff structures: A case study of Kathmandu, Nepal.

Many cities in developing countries are searching for financially motivated behavior-based alternatives, such as pay-as-you-throw (PAYT) tariff mechanisms, over conventional methods. This study explores the determinants and readiness for willingness-to-pay (WTP) for introducing unit-based PAYT tariff structures in Kathmandu, Nepal. Two distinct colored volume-based recyclable plastic bags (1 L and 20 L) waste collection systems were introduced, and their acceptability was assessed using the contingent valuation method (CVM) spike model. The findings from a survey of 401 households revealed that the public shows their willingness to replace existing fixed tariff structures with PAYT systems, with WTP values of NRs 36.1 and NRs 42.14 (USD 0.28 and 0.32) for each 1 L and 20 L bags, respectively. Income, age, sex, family size, and household status were the key determinants. Tenants were more willing to pay than homeowners. The PAYT system has a substantial additional revenue generation of 326 % compared to conventional fixed tariff structures and reduces the financial burden of waste financing for public entities. Innovative PAYT tariff structures are also expected to be an effective tool not only from a revenue generation perspective, but also as a financially motivated behavioral tool for waste segregation, reduction, and recycling for sustainable waste management in developing countries.

Effect of acidification pretreatment on two-phase anaerobic digestion of acidified food waste.

Acidified food waste significantly disrupts anaerobic digestion, highlighting the need for effective solutions to mitigate its impact. This study presents a method that utilizes acidified sludge to pretreat acidified food waste, thereby significantly improving the efficiency of hydrolysis and acidogenesis. After acidification pretreatment, hydrolysis efficiency improved from 64.54 % to 96.51 %, while acidogenesis efficiency increased from 34.82 % to 49.95 %. Additionally, the concentration of short-chain fatty acids and hydrogen production in the acidification pretreatment group increased by 45.89 % and 48.67 %, respectively. The pretreatment group exhibited a biochemical methane potential of 512.84 ± 13.73 mL/(g volatile suspended solids), which was 35.77 % higher than that of the control group. Mechanism analysis revealed that the higher abundance of genes associated with lactate dehydrogenase in the acidified sludge facilitated the rapid degradation of lactic acid. Moreover, the abundant Clostridium butyricum in the acidified sludge promoted the targeted conversion of lactic acid and other organic matter into butyric acid within the food waste system. This efficient butyric acid fermentation improved the fermentation environment and provided abundant substrates for methane production. This study introduces a promising bio-based strategy to improve the anaerobic digestion efficiency of acidified food waste.

Circular economy strategies in sedimentary phosphate mine reclamation: Development of technosol from phosphate waste rock.

Proper management of mine waste plays a crucial role in minimizing environmental impacts. One potential solution to tackle this problem involves transforming mine waste rock into soil to facilitate the process of mine restoration. The aim of this study was to assess the mineralogical, chemical, and physical characteristics of technosol derived from phosphate mine waste dumps. Following this evaluation, a novel rehabilitation strategy was proposed. For this purpose, a total of 32 samples were systematically collected across a 4 ha area of technosols, which had been established in accordance with the waste rock soil rehabilitation strategy involving geomorphic reshaping. According to the findings, phosphate mining left the soil with a sandy texture, resulting in a degraded soil structure with severely unfavorable crop growth conditions, notably poor stability, and low water retention. The chemistry of the studied soils was characterized by the dominance of CaO (29.02 wt%± 1.01) > SiO2 (27.61 wt% ± 0.61) > P2O5 (11.34 wt% ± 0.23) > MgO (5.97 wt%±0.16). Mineralogically, the samples were mainly formed by quartz, dolomite, calcite, apatite, and clay minerals. The prevalence of dolomite played a significant role in enhancing the accessibility of Mg as an essential nutrient and the occurrence of apatite in the soil resulted in the presence of P2O5. However, the abundance of Ca was linked to three major minerals: calcite, apatite, and dolomite. X-ray fluorescence analyses demonstrated that the concentrations of Fe2O3, K2O, and SO3 did not exceed 2 wt%.Organic matter, represented by SOC <0.2% and N < 0.02%, demonstrated an extraordinary deficiency in the study area. The analysis of element bioavailability confirmed that the soil was rich in Ca (10383,26 mg/kg), Mg (278,47 mg/kg), Zn (12,82 mg/kg), and Cu (3,7 mg/kg) but deficient in other essential nutrients such as P, K, S, Mn, and Fe. Our research results provide a set of recommendations aimed at enhancing existing mine rehabilitation practices applicable to both pre- and post-rehabilitation phases, leveraging automated mineralogy and circular economy principles. Notably, we propose a rehabilitation strategy to be implemented prior to the geomorphic reshaping phase, which is intended to reduce costs and efforts associated with soil reconstitution.

Critical care nurses' experiences on environmental sustainability: A qualitative content analysis.

BACKGROUND: Intensive care units (ICUs) are the primary producers of greenhouse gas emissions within hospitals, due to the use of several invasive materials. Nurses represent a large portion of the healthcare workforce and can be pivotal in promoting sustainability practices. Several international reports have suggested that nursing can help achieve the sustainable development objectives set by the United Nations. AIMS: The purpose is to explore behaviour related to environmental sustainability in intensive care nurses. STUDY DESIGN: A qualitative content analysis comprised of in-depth interviews involving 27 ICU nurses, who were each asked the same open-ended question. The transcripts collected were then analyzed and organized by a team of independently-working researchers. The analysis of the extrapolated concepts was carried out following the Neem M. (2022) method. The study is supported by a grant from the Centre of Excellence for Nursing Scholarship, Rome, July 2024. FINDINGS: The main recurring themes are as follows: (1) concepts of environmental sustainability in ICUs, (2) critical issues related to sustainable intervention in the ICUs (3) proactive environmental sustainability attitudes in ICUs. Time to know, define criticality, and improve is the conceptualization of sustainable behaviors experienced by ICU nurses. CONCLUSIONS: Taking the time to know and define the critical issues for implementing sustainable behaviours in the ICU, turned out to be the key to enforce the mindset of green nursing thinking. IMPLICATIONS TO CLINICAL PRACTICE: Sustainability behaviours need to be proposed and verified by ICU managers by creating sustainability teams and promoting a good working environment, founding the progression to green ICUs by focusing on health impact education and mindfulness.

Biosurfactant production by Bacillus cereus GX7 utilizing organic waste and its application in the remediation of hydrocarbon-contaminated environments.

The use of biosurfactants represents a promising technology for remediating hydrocarbon pollution in the environment. This study evaluated a highly effective biosurfactant strain-Bacillus cereus GX7's ability to produce biosurfactants from industrial and agriculture organic wastes. Bacillus cereus GX7 showed poor utilization capacity for oil soluble organic waste but effectively utilized of water- soluble organic wastes such as starch hydrolysate and wheat bran juice as carbon sources to enhance biosurfactant production. This led to significant improvements in surface tension and emulsification index. Corn steep liquor was also effective as a nitrogen source for Bacillus cereus GX7 in biosurfactant production. The biosurfactants produced by strain Bacillus cereus GX7 demonstrated a remediation effect on oily beach sand, but are slightly inferior to chemical surfactants. Inoculation with Bacillus cereus GX7 (70.36%) or its fermentation solution (94.38%) effectively enhanced the degradation efficiency of diesel oil in polluted seawater, surpassing that of indigenous degrading bacteria treatments (57.62%). Moreover, inoculation with Bacillus cereus GX7's fermentation solution notably improved the community structure by increasing the abundance of functional bacteria such as Pseudomonas and Stenotrophomonas in seawater. These findings suggest that the Bacillus cereus GX7 as a promising candidate for bioremediation of petroleum hydrocarbons.

Integrated municipal solid waste management using ArcGIS tools: A case of akaki-kality sub-city, addis ababa, ethiopia.

This study aimed to optimize the solid waste collection and transportation system using ArcGIS Network Analyst and location-allocation tools. The generated solid waste was characterized by proximate analysis. The generation rate and composition were determined according to standard methods. The average solid waste generation rates for households, commercial sites, institutions, and recreational places were 0.48 kg/c/day, 15.03 kg/fac/day, 9.32 kg/fac/day, and 22.8 kg/fac/day, respectively. The estimated total generation rate of the sub-city is 207,004.03 kg/day and 712.13 m3/day as discarded base. Composition analysis revealed that food waste is the major component of municipal solid waste, with estimated weight and volume of 134,696.08 kg and 299.46 m3, respectively. Proximate analysis indicated that food and textile wastes have relatively high moisture content and fixed carbon. Candidate pre-collection bin allocations were optimized based on factors such as road network, distribution of solid waste generators, and existing temporary dumping sites, resulting in 1052 potential bin locations. Transfer station allocation was optimized by considering land use-land cover, slope, and geology. Twelve transfer routes and four transport routes were established to efficiently serve the bins and final waste destinations. In conclusion, the study demonstrates that ArcGIS Network Analyst and location-allocation tools can effectively optimize the municipal solid waste collection and transportation system, providing a robust framework for improving waste management efficiency. However, further research is recommended to validate these findings through field application.

Microbial approach towards anode biofilm engineering enhances extracellular electron transfer for bioenergy production.

Applying microbial electrolysis cells (MEC) is a biological approach to enhance the growth of high amounts of electroactive biofilm for extracellular electron transfer. The electroactive biofilm degrades the organics by oxidizing them at the anode and producing electrical energy. Addition of waste-activated sludge (WAS) with fat grease oil (FOG) produces an optimal reactor environment for microbial growth to enhance the exchange of electrons between cells via microbial electrolysis. The present work aimed to investigate the microbial approach to increase the extracellular electron transfer (EET) in microbial electrolysis cells. Results revealed that metabolites in electroactive microbes (EAM) grow viable cells that initiate high EET at anode sites. At optimum WAS with FOG addition, volatile fatty acid and current generation yield production was 2.94 ± 0.19 g/L and 17.91 ± 7.23 mA, accompanied by COD removal efficiency of 89.5 ± 14.4%, respectively. This study introduces a novel approach to anode biofilm engineering that significantly enhances extracellular electron transfer, offering a fresh perspective on bioenergy production. Our approach, which demonstrates that anodic biofilm enhances intercellular electron transfer, increases NADH-NAD ratio, and increases metabolite yield-fluxes, has the potential to revolutionize bio-electricity production. Results indicated that the electrolysis highlights MEC performance in power generation of 788 mV with 200 mL of anode volume of active viable cells by utilizing WAS with 11% FOG. The achievements of this study provide critical parameters for the anode biofilm engineering, demonstrating how growth cell volume, intercellular electron transfer, and increases in NADH-NAD ratio are evidence of an increase in the EET, compelling evidence for the resilience treatment and efficient current production. These findings are significant in advancing our understanding of bioenergy production.

Fast, sensitive, and sustainable colorimetric detection of chlorogenic acid in artichoke waste material.

Caffeoylquinic acids (CQAs) are nutraceutical polyphenols highly represented in natural sources, including artichoke waste (AW). In this study a colorimetric method for rapid and sustainable detection of a 5-CQA isomer (Chlorogenic acid) in AW extract was developed by using alkaline Tris buffer (10 mmol L-1, pH 9) to generate a yellow color associated with 5- to 3-CQA isomerization reaction, as suggested by NMR and MS analyses. The strong absorbance at 360 nm was followed by standard UV-Vis methodology. The colorimetric assay was exploited for detection of 5-CQA into leaf extract from artichoke, obtaining a value of 15.2 ± 0.3 µg/mg of dry extract, in agreement with HPLC analysis (14.3 ± 0.7 µg/mg, 106 ± 2 % recovery) used as validation technique, with excellent linear correlation and precision (R2 = 0.9996, avRSD% = 3.2 %). The method is fast and selective, offering a valuable tool for nutraceuticals identification and food waste valorization.

In-situ production of amino acid-rich monoammonium phosphate from chicken feathers provides superior efficacy compared to physical blending.

A large amount of feather waste is discarded annually, leading to severe environmental pollution problems. Meanwhile, to improve the utilization efficiency of phosphate fertilizers, this study utilized wet-process phosphoric acid (WPPA) to hydrolyze feathers in-situ, producing ammonium amino acid phosphate (AAMAP), and set up physically mixed ammonium phosphate (ARMAP) as a control. The application effects of AAMAP and ARMAP produced under different conditions on bok choy growth were investigated. The results showed that AAMAP consistently outperformed ARMAP in promoting yield, with fresh weight and dry weight increases ranging from 1.38 % to 26.06 % and 5.69 % to 20.67 %, respectively. Among all treatments, the AAMAP (150 g/L-3) group was the most effective, increasing fresh weight and dry weight by 37.13 % and 46.13 % compared to the blank control group. Analysis revealed that the superior application effect of AAMAP was attributed to the elimination of the water-insoluble NH4MgPO4·H2O crystals due to amino acid chelation, leading to improved phosphorus and magnesium utilization, as well as the formation of phosphoesters. Furthermore, economic analysis showed that the addition cost of AAMAP was only 28.52 % of ARMAP. This method of utilizing WPPA to hydrolyze feathers in-situ for AAMAP production is an economical and effective approach to treat feather waste and enhance the utilization efficiency of phosphate fertilizers.

Assessment and management of construction and demolition waste in tier 2 cities of Karnataka, India: a case study of Hubli-Dharwad and Davanagere.

The present study examines the current practices for managing construction and demolition waste (CDW) in two tier-2 cities of Karnataka state: Hubli-Dharwad and Davanagere. The research highlights the quantification, characterization, and effective management strategies for CDW. CDW dumping sites were identified through field visits conducted across all wards of the cities and recorded using a mobile-based app. At each site, data were collected on the types of vehicles dumping CDW, the frequency of dumping, the volume of waste in the vehicles, and the quantity of CDW removed for reuse. The dumping sites were categorized into large, medium, and small based on the area and volume of waste. In total, 130 unauthorised dumping sites were identified in Hubli-Dharwad and 62 in Davanagere. The study estimated that Hubli-Dharwad generates approximately 607 tonnes per day (TPD) of CDW, while Davanagere produces around 287 TPD. The characterization of CDW revealed that in Hubli-Dharwad, CDW consists of 14.4% concrete, 25.5% brick and mortar, 39.1% soil and aggregates, and 20% other materials. In Davanagere, the composition includes 19% concrete, 29% brick and mortar, 38% soil, and 14% other materials. Based on these findings, the study proposes a system for the collection and transportation of CDW and recommends suitable recycling technologies. While the approach outlined in this paper is well-suited for urban local bodies to assess CDW, the data on CDW reuse and recycling is primarily based on informal practices. This makes accurate quantification challenging and subject to variation over time due to a lack of regulatory oversight. Additionally, the study provides only a snapshot of CDW generation and management at a specific point in time, potentially missing seasonal variations or long-term trends in waste handling.