Low Concentrations Of Heavy Metals Research Articles

Microbial phosphorus removal and recovery by struvite biomineralisation in comparison to chemical struvite precipitation in municipal wastewater

Microbial biomineralisation is attracting significant interest as an innovative process to recover nutrients from wastes. Nevertheless, little is understood about the requirements to form struvite using biological pathways in wastewater and how does this compare with conventional chemical processes. To address this gap, Halobacterium salinarum, Bacillus pumilus, Brevibacterium antiquum, Myxococcus xanthus and Idiomarina loihiensis were grown in wastewater to explore the relationships between cell growth, nutrients levels and properties of the recovered precipitates. The microorganisms were capable of removing ortho-phosphate (PO4-P) from municipal wastewater at concentrations ranging from 5.4 to 62.4 mg PO4-P/L. Visible crystals of biological struvite (bio-struvite) (identified by morphology XRD and elemental analysis), were observed at PO4-P ≥ 19.7 mg/L, compared to chemical struvite precipitation at 62.4 mg/L PO4-P (with pH adjustment). The initial nutrient concentrations presented a strong positive correlation with bio-struvite production yields and crystal size distribution. B. antiquum distinguished itself by relatively stable PO4-P removal (68–97%) independent of the initial nutrient concentration, with effluents containing as low as 1 mg PO4-P/L. The recovered bio-struvite presented high purity with low heavy metal contents, meeting regulations for inorganic fertiliser. The microbial processes for phosphorus (P) recovery as bio-struvite presented several key advantages: bio-struvite crystals were released to the wastewater and recoverable by filtration at PO4-P ≥ 19.7 mg/L, no need to adjust pH, bio-struvite crystals had purity equivalent to 11.8–12.3% P and low heavy metal content, which was similar or better than that of chemical struvite (12.6% P). This study validates bio-struvite’s relevance for low nutrient concentrations.

Study on the qualitative assessment of in-vessel food waste compost by indexing method

The consumption of different food-based goods produces a considerable amount of waste that needs to be conserved in an eco-friendly manner. A study was carried out on food waste compost made from the in-vessel compost process for use in agriculture and its marketability for its fertility and contamination potential. Food waste samples were collected from the canteen and hostels of GITAM University, Visakhapatnam (Andhra Pradesh), India and were transferred to a 125Kg in-vessel food waste composter (Molten Mind F125) and allowed to digest for 24 hrs followed by curing for seven days. After curing, the samples were characterized for nutrient content for fertility index (FI) and heavy metal contamination for clean index (CI). The compost quality index was derived from FI and CI to assess its suitability for agriculture. The pH of the food waste compost sample was reported as 8.4 and the C/N ratio was 28, which was higher than the standard ratio (15-20). The other physicochemical characteristics were analyzed using the standard methods and the concentration of metals was analyzed using Inductively Coupled Plasma Mass Spectrometry ( ICPMS). From the analysis, it was evident that heavy metal concentrations were well within the permissible limits. Further, the compost was characterized to know the fertility index (FI) and contamination index (CI) and its suitability to the soil. FI value was reported as more than 3.1 and CI value more than 4, which indicated that compost was best in quality, having high-value potential and low heavy-metal content, which will be suitable for high-value crops such as organic farming.

Influence of the surface modification of granular-activated carbon synthesized from macauba on heavy metal sorption.

Adsorption on activated carbon is a promising technique for the treatment of low-concentration heavy metal pollutants in water with high efficiency and simple operation. However, commercial-activated carbon is often associated with high costs. Therefore, much attention has been given to activated carbon derived from low-cost agricultural and residual biomass. In this work, adsorption of Zn, Cd, and Pb ions in aqueous solutions was conducted using granular-activated carbon obtained from macauba palm, biomass waste of biofuel production, after surface modification using different methods. The adsorbents were obtained in granular form which facilitates all steps of the use, recovery, and reuse of the material, differently from the powdered-activated carbon normally used. The materials were characterized by using XPS, elemental analysis, N2 sorption (BET method), and zeta potential measurements. Such techniques allowed observation of the functionalization of the carbon surface. The materials presented high adsorption capacities when compared to other works in the literature, with a capacity of approximately 7.69, 8.42, and 1.63mmolg-1 for Zn2+, Cd2+, and Pb2+, respectively. In addition, the materials showed a high capacity to be reused, removing 75% of Pb and 99% of both Cd and Zn after 4 cycles.

Programmable and low-cost biohybrid membrane for efficient heavy metal removal from water

Heavy metal pollution in rivers and lakes from industrial development poses great challenges to environmental remediation, especially of low-concentration metal ions. Current technologies for removing low-concentration heavy metal ions are typically expensive, and there is therefore an urgent need to develop new strategies. Low-cost microbial amyloid nanofibers (MAN) have demonstrated excellent abilities in removing heavy metal ions. In this study, we used synthetic biology strategies to design programmable MAN in silico and create artificial MAN for biohybrid membrane preparation. It was found that MAN could be largely produced and self-assembled, and it exhibited a removal rate of more than 98 % for 50 mg/L lead ions. Furthermore, genetic edits of MAN with functional peptides endowed the specific binding ability to heavy metals even at 1 mg/L. Impressively, biohybrid membranes using activated carbon as the supporting material based on programmable MAN showed long lifecycles and low costs in scale-up water purification systems. This study provides a programmable and low-cost strategy for the efficient treatment of heavy metal wastewater.

Generation of novel, hygienic, inhibitive, and cost-effective nanostructured Core-shell pigments

The key goal of this study is to develop new, eco-friendly, and cost-effective nanostructured core-shell pigments based on nanosilica extracted from rice husk agro-waste to offer both anticorrosive and antimicrobial characteristics. The nanostructured core-shell pigments were created by depositing a thin shell of ZnO and/or CuO nanoparticles over a low-cost core of nanosilica extracted from rice husk agricultural waste. The synthesized pigments were characterized using X-ray diffraction, X-ray fluorescence, scanning electron microscopy, energy-dispersive X-ray, and transmission electron microscopy. These pigments were incorporated into alkyd resin to evaluate their antimicrobial and anticorrosive performance. Immersion tests, electrochemical impedance spectroscopy, and scanning electron microscopy were used to determine the corrosion resistance of coatings containing the prepared nanostructured core-shell pigments. The results deduced that the coating resistance followed the sequence ZnO.CuO/Si > ZnO/Si > CuO/Si > nanosilica. Furthermore, the antimicrobial activity of these coatings was investigated using disk diffusion and shake flask methods. The results revealed that coatings containing the prepared pigments could offer good antimicrobial activity. This research shows that these novel nanostructured core-shell pigments may act as anticorrosive and antimicrobial pigments in a single-layered coating at a low cost. Additionally, because they are constructed mainly of nano-silica recovered from agro-waste and have a low concentration of heavy metals, these pigments are both cost-effective and eco-friendly.

Enhanced adsorption performance of polypyrrole composite electrode with ionic liquid doped for low concentration heavy metals in CDI

Recently, capacitance deionization (CDI) has attracted much attention as an energy-saving and high-efficiency wastewater treatment technology, in which electrode materials play a significant role. In this work, ionic liquid (1-ethyl-3-methylimidazole tetrafluoroborate)-doped composite electrode materials (PPy-IL/CS/CNT) were prepared by electrochemical deposition and applied in the heavy metal ions wastewater adsorption. Compared with PPy/CS/CNT, PPy-IL/CS/CNT has improved the specific capacitance (358.76 F/g) and specific surface (79.99 m2/g) because of the doping of IL, which substantially improves the agglomeration phenomenon in the morphology. After 1000 cycles of CV, the specific capacitance decay is only 13.51%, which shows that the prepared material has excellent cycling stability. The adsorption of PPy-IL/CS/CNT can reach 35.84 mg/g for 100 mg/L Cu2+ solution, which is nearly 2 times as much as PPy/CS/CNT, in addition, the adsorption of Ag+ (26.43 mg/g) and Fe3+ (37.82 mg/g) by PPy-IL/CS/CNT is also pretty impressive. Therefore, this study presents an effective basis and new sight into the industrialization of CDI technology for the treatment of heavy metal ion wastewater.

A new strategy for selective recovery of low concentration cobalt ions from wastewater: Based on selective chelating precipitation-flotation process

BackgroundA significant amount of low-concentration heavy metal ion wastewater is generated daily by the mining and metallurgy industry, endangering human health and the environment. A novel method of selective chelating precipitation–floatation of copper and cobalt ions is proposed for the recovery of cobalt from wastewater. MethodsBased on the chelation of cobalt and copper ions with α-nitroso-β-naphthol (NN), the flotation process is adopted to solve the problem of fine particle separation from solution in low-concentration ions removal. Significant findingsUnder the optimized precipitation flotation conditions, the flotation recovery ratios of the copper, cobalt, and zinc ions were found to be 98.47%, 42.48%, and 9.35%, respectively, and the separation effect of cobalt and zinc showed to be outstanding, as their separation factor reached 598. Industrial wastewater also has a good flotation separation effect. Based on the mechanism studies, Co2+/Co3+ and Cu2+ were selectively chelated by NN to form hydrophobic NN-Co/Cu precipitation particles. Moreover, electrostatic attraction is the main force in the proposed flotation process. Eventually, we tried calcination to recycle the flotation products to verify the potential of the cobalt–copper composite oxides in capacitor materials. The results prove that the precipitation–flotation method has great efficiency and potential for selectively recovering low-concentration metal ions and separating fine particles from solution.

Tissue distribution and association of heavy metal accumulation in a free-living resident passerine bird tree sparrow Passer montanus

Passerine birds have been increasingly used as effective sentinels of ecosystem contamination. They can provide direct evidence of the bioavailability and accumulation of heavy metal elements in the environment. In this study, the bioaccumulation of four heavy metals (Cu, Zn, Pb, and Cd) and Ca in different organs and tissues (feathers, internal organs, skeletons, and muscles) of an urban bird, tree sparrow (Passer montanus), collected from a polluted site [Baiyin (BY)] and a relatively unpolluted site [Liujiaxia (LJX)], and their associations were investigated. There were significantly higher and lower concentrations of heavy metals and Ca, respectively, in different organs and tissues of sparrows in BY than those in LJX. However, except for Pb, the heavy metal levels were below the threshold of sublethal effects. Age-dependent variations in metals were quantified, and it was found that adult bird contained higher concentration of different organs and tissue metals, except for feathers, compared with nestlings and juveniles. The tissue distribution of heavy metals in sparrows of different ages and sex was similar in the two study sites, and heavy metal elements were mainly accumulated in the feathers. This study further investigated the correlation between heavy metals in different organs and tissues and found that the correlations between them were strong in nestlings and adults but weak in juveniles. In addition, Pb and Cd in internal organs, skeletons, and muscles of young sparrows can be estimated using feathers, whereas Cu and Zn were found in adult sparrows. Altogether, our results suggest that tree sparrows will serve as valuable biomonitors of environmental heavy metal pollution and will underscore the importance of tissue types in avian ecotoxicology field studies.

Preliminary assessment of hazelnut shell biomass as a raw material for pellet production

We evaluated the use of hazelnut shell (HS) for pellet production. The investigation of chemical properties, such as the calorific value, low ash, nitrogen, sulfur and chlorine content as well as low heavy metal contents, reveals that the proposed biomass is suitable. However, fuel agglomeration is complicated possibly by some chemical (high content of extractives and lignin) and mechanical properties (spherical shape of particles). Therefore, the blend of HS with pine sawdust is examined in an iterative study, and pellet production is feasible only for percentages of HS lower than 30% in semi-industrial pelleting. The produced pellets exhibit properties compatible to those of industrial and domestic standards; however, as expected the mechanical durability and bulk density needs to be improved. Further studies to identify the optimal operating conditions for the evaluated blend can provide strategies to satisfy the projected increase in pellet demand.

Characterization of Agro-Livestock Wastes for Composting in Rural Zones in Ecuador: The Case of the Parish of San Andrés

In Ecuador, the agriculture and livestock sectors are very important within the economy of rural areas. These activities generate a large amount of waste whose management is not optimized. Thus, the aim of this work was to characterize different agro-livestock wastes generated in a rural area, the parish of San Andrés (Chimborazo-Ecuador), in order to know their composition to design suitable composting processes for their treatment. To this end, different physicochemical and chemical parameters were determined in 24 crop residue samples and 18 manure samples, and two piles were elaborated with the same proportion of wastes (51% vegetable residue + 35% cow manure + 14% sawdust) and composted by turning or passive aeration. Throughout the composting process, the temperature and oxygen concentration were recorded and the evolution of different physicochemical, chemical, and biological parameters and the quality of the final composts were studied. The results indicated that the agro-livestock residues presented notable macro and micronutrient and organic matter contents and low levels of heavy metals, these properties being positive for their subsequent treatment in a co-composting experiment. This experiment demonstrated that the composting processes are a feasible strategy for the treatment of these residues and yield compost with an adequate agricultural quality (notable nitrogen content, low heavy metal and soluble mineral salt contents and 92–94% in germination index). Moreover, the passive aeration system can be recommended because this aeration method reduced composting times and the work associated with the process. However, more studies are required on this composting system and other agro-livestock wastes to establish a management protocol for all the waste generated, which will contribute to the sustainability of the agro-livestock sector in the area studied.

Comparative and Health Risk Assessment of Heavy Metals in Mangrove Forest and Farm - Bred African Giant Snails (Archachatina Marginata)

Snails are good source of protein for different classes of people. The aim of this work is to compare and assess the health risk of the heavy metals in mangrove forest and farm - bred snails, as sources of protein. Twelve snails (six mangrove forest and six farm - bred) of two sizes (big and small) were sourced from Bayeku mangrove forest and Snail Farm at Second gate of Lagos State University of Science and Technology (LASUSTECH) respectively. The, Fe, Cd, Cr, Ni, Cu, Pb, and Zn concentration of the snails were evaluated using standard analytical methods. The data obtained were subject to differential and inferential statistics using a statistical package (SPSS 22.0 version) and compare with Food and Agriculture Organization (FAO) limit. Fe (732.32 - 734.24 mg/kg), Cu (145.17 - 145.19 mg/kg), Zn (62.38 - 62.51 mg/kg) of big snail from mangrove forest were the highest compared with Fe, Cu, and Zn in mangrove forest (small), farm bred (big and small) snail. Cr (77.20 - 77.46), Ni (21.14 – 21.28), and Pb (1.20 - 1.22) mg/kg in small snail (mangrove forest) were the highest. Cadmium (6.83 - 6.84 mg/kg) of the farm bred (big snail) was the highest. Mangrove forest bred snail; Fe (733.26±0.96), Cr (38.01±0.78), Ni (50.32±0.37), Cu (145.18±0.01), and Zn (62.43±0.07) mg/kg were significantly higher than their corresponding FAO Limits. Farm - bred snail Cr (38.99±0.21), and Zn (36.80±0.01) mg/kg were significantly higher than their corresponding FAO permissible limits. However, farm bred has lower heavy metal concentrations than mangrove forest bred. Hence, farm bred are better product.

Removal of bisphenol A (BPA) by fermented sludge-derived granular biochar from template-like method: From batch experiment to continuous operation

Endocrine disruptors have biological toxicity and can interfere with the endocrine system of organisms. They widely exist in natural water bodies. Here, the granular biochar was prepared from fermented sludge for the first time by using cationic polyacrylamide as template agent via a template-like method. The as prepared biochar was investigated for the removal of BPA in aqueous media by batch experiment and continuous flow experiment. The pyrolysis temperature and template concentration had a great influence on the properties of residual biochar and BPA capture. The static adsorption results show that when the template concentration was 1% with the pyrolysis temperature of 800 °C, the optimal biochar P-1%− 800 achieved the BPA adsorption value up to 84.78 mg/g. Its adsorption behavior, influencing factors, and recycling capability on BPA reduction were evaluated. Kinetics, isotherms and characterization analysis suggested that the adsorption mechanism involved pore filling, electrostatic attraction, π-π interactions and hydrogen bonding. Good regeneration performance, low concentration heavy metal leaching and lasting continuous flow stability in fixed-bed device under different water quality background demonstrated that fermented sludge-derived granular biochar P-1%− 800 is a desirable adsorbent for reducing BPA in complex water environment.

Assessment of spatio-temporal variation of heavy metals in Tunga reservoir at Gajanur, Karnataka

Surface water samples from Tunga reservoir at Gajanur were analyzed quantitatively for the estimation of five heavy metals such as Iron, Manganese, Lead, Copper and Zinc using atomic absorption spectrophotometer (AA 240 FS, Varian) under specific wave lengths. The values of metals analysed found in the increasing order as follows: Cu (0.9%), Mn (9%), Fe (9%), Pb (12%) and Zn (69%). Metals studied are found throughout the study period confirming that heavy metals are naturally occurring in water. The probable sources of heavy metals in Tunga Reservoir are lithogenic, anthropogenic and agricultural runoff. Hence, very low concentrations of heavy metals were recorded which lies within the acceptable limits of BIS and WHO. The data obtained has been statistically analysed for mean, standard deviation and standard error by using SPSS 16.0 package in Microsoft office excel 2007. Inter relationships among the heavy metals has been worked out by adopting Karl Pearson's correlation coefficient using SPSS 10.0 software. The results revealed that, as such no ecological risk to humans from the waters of the reservoir.

Phytoremediation of Heavy Metal Contaminated Soils Using Safflower

The promotion and gradual replacement of fossil fuels with renewable sources increasing the competition between food and fuel. Therefore, energy crops could be produced on unproductive marginal land due to unfavorable conditions, such as limitations in nutrient and water availability or the presence of contaminants such as hydrocarbons or heavy metals. In the case of soils contaminated with heavy metals, one option could be the use of plants to extract or immobilize the contaminants in the soil in a process called phytoremediation. Carthamus tinctorius L. is an annual herbaceous plant with a deep root system, and the oil extracted from the seeds is an excellent oil for conversion into biofuel. It appears suitable to be used in the phytoremediation process, increasing the opportunity to valorize polluted areas and reducing the risk of abandonment of these lands. In this study, C. tinctorius was tested in soils contaminated with zinc, cadmium, lead, and nickel at different concentrations to evaluate the effects on yield and heavy metal content in the different parts of the plant. The experiment highlights the tolerance of Safflower to the cultivation in heavy-metal-polluted soil; in fact, a low reduction in biomass yield was observed. Among the evaluated heavy metals, the higher susceptibility was observed at the highest concentrations of zinc and cadmium. Generally, safflower concentrates heavy metals in the belowground biomass. The relative low concentrations of heavy metals in some parts of the aboveground biomass could suggest the possibility of using it as a feedstock for bioenergy conversion.

Appraisal and validation of a method used for detecting heavy metals in poultry feed in Bangladesh.

Low concentrations of heavy metals are toxic and pose a serious threat to human health and the environment. Therefore, regular assessments of the toxic metal content in poultry feed are crucial for evaluating feed quality and customer safety. It is difficult to determine the heavy metals in the poultry feed at the trace amount. Therefore, this study aimed to validate this method through the detection of three heavy metals, chromium (Cr), cadmium (Cd), and lead (Pb), in poultry feed samples. Graphite furnace atomic absorption spectrometry (GF-AAS) method was used to analyze the heavy metals in poultry feed according to the guidelines given by the Council Directive 333/2007/EC, Commission Decision 657/2002/EC. In this study, various parameters such as linearity check, limit of detection (LOD), limit of quantification (LOQ), recovery percentage, precision checks, repeatability, reproducibility, and uncertainty measurement were considered to validate and assess the method following international guidelines. Heavy metals, such as Pb, Cr, and Cd, were analyzed from the feed samples in the laboratory using the GF-AAS method (Model: AA-7000 Shimadzu, Japan) with high purity argon as the inert gas, and the absorbance was read at wavelengths of 283.0, 357.9, and 228.8 nm, respectively. The coefficient of variation (CV%) for system suitability and precision data was <10% for all the metals (Pb, Cr, and Cd) detected in this study. The overall CV% of repeatability and reproducibility ranged from 8.70% to 8.76% and 8.65% to 9.96%, respectively. The linearity of the calibration curves was excellent (r2 > 0.999) at various concentration levels for the three different metals. The recovery (%) was found to be 94.53, 93.97, and 101.63% for Pb, Cr, and Cd, respectively. The LOD values in feed were 0.065, 0.01, and 0.11 mg/kg, and the LOQ values were 0.22, 0.03, and 0.38 mg/kg for Cr, Cd, and Pb, respectively. The values recorded for the measurement uncertainty (%) were 11.48, 4.43, and 12.42% for Cr, Cd, and Pb, respectively. The results show that these study criteria or parameters have met the validated or acceptable range. Therefore, it is a reliable technique that can be used undoubtedly for the routine analysis of heavy metals in poultry feed samples across the globe.

The emerging potential of natural and synthetic algae-based microbiomes for heavy metal removal and recovery from wastewaters

Heavy Metal (HM) bioremoval by microbes is a successful, environment-friendly technique, particularly at low concentrations of HMs. Studies using algae, bacteria, and fungi reveal promising capabilities in isolation and when used in consortia. Yet, few reviews have emphasized individual and collective HM removal rates and the associated mechanisms in natural or synthetic microbiomes. Besides discussing the limitations of conventional and synthetic biology approaches, this review underscores the utility of indigenous microbial taxon, i.e., algae, fungi, and bacteria, in HM removal with adsorption capacities and their synergistic role in microbiome-led studies. The detoxification mechanisms studied for certain HMs indicate distinctive removal pathways in each taxon which points to an enhanced effect when used as a microbiome. The role and higher efficacies of the designer microbiomes with complementing and mutualistic taxa are also considered, followed by recovery options for a circular bioeconomy. The citation network analysis further validates the multi-metal removal ability of microbiomes and the restricted capabilities of the individual counterparts. In precis, the study reemphasizes increased metal removal efficiencies of inter-taxon microbiomes and the mechanisms for synergistic and improved removal, eventually drawing attention to the benefits of ecological engineering approaches compared to other alternatives.

Spatiotemporal variations of heavy metal historical accumulation records and their influencing mechanisms in the Yangtze River Estuary

Complex transformations of heavy metals in the mega-river-estuary continuum limit our understanding of their pollution history. This study investigated sedimentary compositions of heavy metals, major elements, total organic carbon, grain size, and radionuclides to study spatiotemporal variations in heavy metal accumulation patterns and their controlling mechanisms in four sediment cores (E1-E4) from the Yangtze River Estuary (YRE). Results show that only E3 in the distal YRE front mirrors well the heavy metal pollution history due to its continuous deposition in a stable sedimentary environment, while E1 and E2 record the influence of riverine and estuarine projects and processes apparently. E1 in the proximal YRE front registers intense human disturbance through sediment dredging and dumping activities to produce a thick layer of abnormal low 210Pbex and minor heavy metal concentrations. E2 in the intermediate YRE front demonstrates the recently increasing influence of reduced sediment discharge by its upcore coarsening trend with decreased heavy metal concentrations. Flood and storm events left different imprints in core sediments of E2 and E3 by their coarse stratal units with fewer heavy metal concentrations. The source analysis indicates that heavy metals in estuarine sediments mainly come from natural processes but are significantly affected by human activities. A direct linkage of the heavy metal accumulation history with the socioeconomic development in recent decades is found by a comparison study of core data from the tidal river to the estuary, albeit with a remarkable spatiotemporal difference, which is jointly determined by grain size, offshore distance, hydrodynamic condition, depositional status, and sedimentation rate besides estuarine processes. This warns us to carefully interpret the heavy metal history from single or sparse core data in a mega estuary system with intense natural forces and human disturbances analogous to the YRE.

Comprehensive evaluation of functional components, biological activities, and minerals of yam species (Dioscorea polystachya and D. alata) from China

Yam (Dioscorea spp.) is a multi-species and multi-purpose tuber crop. In this study, the contents of functional components, biological activities, and mineral elements were evaluated in the yam tubers of D. polystachya and D. alata cultivated widely varieties in China. Significant differences in allantoin contents were observed between interspecific and intraspecific yam varieties, and allantoin contents in the four varieties of D. polystachya were significantly higher than those in the D. alata group; however, no significant difference was observed for dioscin levels in all accessions. Furthermore, the phenol and flavonoid contents of D. alata were higher than those of D. polystachya. Protein profiles obtained using nano-liquid chromatography-tandem mass spectrometry (nanoLC-MS) revealed that the levels of proteins related to allantoin, total phenols, and total flavonoids also changed. In addition, both D. polystachya and D. alata tubers contained highly essential minerals, such as high potassium and magnesium, and low heavy metal contents within the specified pollutant content range. This study provides a foundation for the functional food development of Chinese yams and a reference for breeding high-quality yam varieties.

Potential Applications of Frass Derived from Black Soldier Fly Larvae Treatment of Food Waste: A Review.

The disposal of large amounts of food waste has caused serious environmental pollution and financial losses globally. Compared to alternative disposal methods (landfills, incineration, and anaerobic digestion), composting by black soldier fly larvae (BSFL) is a promising alternative for food waste management. Despite extensive research into larval biomass, another valuable by-product generated from BSFL composting is BSFL frass. However, limited information is available for its potential application. The applications of BSFL frass can be intensified by understanding its physicochemical characteristics, benefits, and challenges of BSFL frass derived from food waste. BSFL frass is harvested after 9–23 days of the experiment, depending on the substrate used in the composting process. The generated BSFL frass could exceed 33% of the original weight of the substrate. The physicochemical characteristics of BSFL frass are as follows: the temperature after harvest is 24 °C to 27 °C, pH is 5.6–8.0, moisture content is 30 to 72%, C/N ratio is 8:1 to 27:1, high nitrogen, phosphorus, and potassium (NPK) content, and low heavy metal content. This paper reviews the characteristics, benefits, and application of BSFL frass. It will also investigate the challenges of using food waste substrates to produce BSFL frass, as well as the best way to pre-treat the food waste substrate and post-treat the BSFL frass.

Theoretical design of phononic crystal cavity sensor for simple and efficient detection of low concentrations of heavy metals in water

Theoretical design of phononic crystal cavity sensor for simple and efficient detection of low concentrations of heavy metals in water