Chemical Waste Treatment Research Articles

Incorporating concrete waste as additive in acidic fermentation–A novel approach for enhanced biohydrogen production and concrete mass reduction

Acidic fermentation (AF) of organic waste/wastewater generates valuable byproducts, including hydrogen, volatile fatty acids, and ethanol; however, its sensitivity to pH drops limits the stability and efficiency of the process. A reversal process, the acidic chemical treatment of concrete waste (CW) to recycle its aggregates, generates calcium hydroxide, which can serve as buffering agent. Meanwhile, integrating both processes can introduce a sustainable win-win approach, which is the aim of this study. To assess this approach, a series of batch AF experiments were conducted at 50 °C and pH 5.5, using glucose as the substrate. Cementitious specimen (1.5 × 1.5 × 0.8 cm) was supplemented to each 200 mL-fermenter. Unamended fermenters, with and without additional NaHCO3-buffering, were used as controls to compare with the amended ones. Introducing cementitious specimens to AF increased H2-production by 2-fold and 1.7-fold compared to controls with and without NaHCO3-addition, respectively, after three consecutive feed-cycles. The surface analysis of incorporated specimen confirmed the Ca, Al, Mg, and Si leaching. The AF efficiency and resulting cementitious mass reduction were further assessed at different organic loads and specimens’ volume, surface area, and porosity (by changing water-to-cement [W/C] ratio). Increasing the organic load from 10 to 20 g-glucose/L resulted in lower H2-production, higher specimen mass reduction (up to ∼32%), and higher Ca2+ release (up to 2 g/L); however, no significant effect was observed when using specimens with higher W/C ratio or surface area. Moreover, the presence of cementitious specimens significantly influenced the microbial composition, leading to notable developments in the abundant genera Thermoanaerobacterium and Bacillus. This study presents a novel approach to sustainably enhancing AF process using CW as both an additive and a treatable substance, with reusable aggregates as a byproduct. It provides valuable insights for optimizing the process and guiding future practical applications. This includes considering various concrete compositions, adjusting organic load conditions, and evaluating long-term stability in larger-scale systems.

Effect of thermal and chemical treatment of olive waste on the mechanical properties of polypropylene random

Effect of thermal and chemical treatment of olive waste on the mechanical properties of polypropylene random

Investigation of the effects of different zwitterions in fabricating smart PVDF/graphene pervaporation membranes

Although membrane separation processes including pervaporation have demonstrated their as an efficiency in chemical waste treatment and resource recovery, the increasingly complex wastes generated by different industrial sectors make it almost impossible for a single membrane that has a fixed set of properties to handler these kinds of contaminants. For this reason, stimuli responsive membranes that have tunable and switchable properties are necessary to be developed. In this research, we explore the impacts of zwitterion compounds as additives to previously formulated PVDF-graphene membrane where graphene was used to facilitate β-phase induction of PVDF, enhancing its piezoelectric properties. The incorporation of zwitterions intended to even promote the β -crystal phase of PVDF, which is also facilitated by an optimized quantity of graphene. The quantified β phase of pristine PVDF- (68.7 %) was observed to increase to 79.4 %-86.32 %, when different zwitterions are added. Moreover, output voltages from piezoelectric testing of membranes under various weights generated a voltage signal up to 1.69 V for the membrane with the 3-(1-Pyridinio-1-propanesulfonate) zwitterion, named as PGzc membrane. Upon employing these membranes to dehydrate isopropanol by pervaporation, it was found out that PG shows a permeation flux (Pf) of 95.49 ± 9.18 g/m2h and 77 % water concentration in permeate (Wcp) while the PGzc.membrane displayed a Pf and Wcp of 988.84 ± 51 g/m2h and 30 %, respectively. But upon application of an external voltage, it was found out that PGzc's Wcp rises from 30 % to 83 % with increasing voltage and while the Pf gradually falls from 988.84 ± 51 g/m2h to 432.51 ± 19 g/m2h. These findings indicate that the addition of an appropriate zwitterion could significantly influence the piezoelectric properties of PVDF-graphene membranes, enhancing their tuning capability under electrical stimulation. This development is important for separation processes and technologies aimed at creating a sustainable society.

Chemical waste treatment based on hydrogen energy (II): Aqueous methyl orange solution under the oxyhydrogen flame

The oxyhydrogen flame (OHF) can generate temperatures as high as 2800 K and a jet flow of highly reactive free radicals including H, OH, HO2 and O. Therefore, it could serve as an effective means for treating various chemical wastes, particularly organic wastes. Building upon our previous research on metal chlorides, we present here a study on the degradation mechanism of aqueous methyl orange (MO) solution under OHF. Although the decolorization of MO solution is rapid, complete degradation is a slow and intricate process. Initially, MO solution undergoes decolorization by breaking the azo bond followed by oxidation processes that convert aminobenzene compounds to benzoquinone and break down the benzene ring until ultimately being fully converted into CO2 and H2O.

Novel ternary Cu0-coupled core-shell Fe0/C nanoparticles micro-electrolysis system toward degradation of organic pollutants: Synergistic effects and removal mechanism

A ternary micro-electrolysis system consisting of carbon-coated metallic iron with Cu nanoparticles (Fe0/C@Cu0) was synthesized for the degradation of sulfathiazole (STZ). Fe0/C@Cu0 catalysts exhibited excellent reusability and stability owing to the inner tailored Fe0 with persistent activity. The connection between Fe and Cu elements in the Fe0/C-3@Cu0 catalyst prepared with iron citrate as iron source exhibited a tighter contact than the catalysts prepared with FeSO4·7H2O and iron(II) oxalate as iron sources. Especially, unique core-shell structure of Fe0/C-3@Cu0 catalyst is more conducive to promoting the degradation of STZ. A two-stage reaction with rapidly degradation followed by gradual degradation was revealed. The mechanism of STZ degradation could be explained by the synergistic effects of Fe0/C@Cu0. Carbon layer with remarkable conductivity allowed electrons from Fe0 transferred freely to the Cu0. The electron-rich Cu0 releases electrons, facilitating the degradation of STZ. Furthermore, the high potential difference between cathode (C and Cu0) and anode (Fe0) accelerate the corrosion of Fe0. Importantly, Fe0/C@Cu0 catalysts exhibited excellent catalytic performance for sulfathiazole degradation in landfill leachate effluent. Results presented provide a new strategy for treatment of chemical wastes.

Analysis of IT Performance on Management HR of Equity Firm Using COBIT 5

An Indonesian equity company is involved in project management for the construction of mechanical systems and the development of electrical and chemical waste treatment systems. With a strong emphasis on continuous improvement and customer satisfaction, the company is dedicated to enhancing its services. However, additional human resources are needed, particularly in the IT field, to align with the business objectives that have not yet been achieved. Despite establishing a minimum requirement of ten years of work experience, the study employs the COBIT 5 framework to evaluate the competency levels in IT governance. The analysis reveals four crucial domains: APO01 (Managing the IT Management Framework), APO07 (Human Resource Management), APO12 (Assessing and Managing Risks), and EDM04 (Ensuring Resource Optimization). It is evident that both EDM04 and APO01 are currently at level 1 and have not reached the desired level. Furthermore, APO07 and APO12 are at level 2 and still need to progress towards their ideal targets. Although Human Resource Management has performed satisfactorily, there is room for improvement in the upcoming year to further enhance its performance.

Influence of Chemical Treatment of Natural Fibres Using the SPSS Method

Chemical Treatments of Natural Fibre Chemical treatment of hazardous waste involves converting it into non-toxic gases by changing or altering its chemical characteristics. Various treatment methods are used, such as reducing solubility or acidity through neutralization or pH adjustment, precipitation or oxidation and reduction, hydrolysis and photosynthesis, chemical oxidation (such as ozonation, electrolytic oxidation, and hydrogen peroxide), and chemical removal (such as alkali metal dichlorine and alkali). Commonly used chemical treatment processes include metallization, activated chemical treatment processes, chemical precipitation, neutralization absorption, disinfection (using chlorine, ozone, UV light), and ion exchange. Natural fibers obtained from the plant kingdom include cotton, flax, jute, bamboo, sisal, and co-conut husks. Cotton and flax are examples of seed hairs, while jute is an example of stem (or bast) fibers. Sisal is an example of leaf fibers. Animal fibers include secretions such as wool, hair, and silk. Popular animal fibers include angora and mohair. This paper reviews various chemical properties of natural fiber-reinforced composites, including changes resulting from the use of natural fibers. Chemical treatments, such as alkali, silane, acetylation, benzoylation, acrylation, malate coupling agents, isocyanates, permanganate, and others are discussed in relation to their effect on the fiber surface. The aim of these treatments is to improve adhe-sion between the fiber and polymer matrix. As a result, water absorption of composites decreases and their mechanical properties are improved. The Statistical Package for Social Sciences, commonly known as SPSS, quickly gained popularity in the 80s and 90s, ex-tending beyond the commercial sector to the social sciences. The original name was dropped, and the name was shortened to "SPSS." Several attempts were made to introduce a word that fits the acronym "SPSS," but they often failed. In the early 2000s, "Statistical Packages and Software Services" was used for some years, but eventually dropped. "SPSS" became just a name and was no longer short for anything. There is, however, a detailed history of SPSS from 1968 to 2009, which is available to anyone interested. The industries included in this study are the non-metal mineral product industry, general equipment manu-facturing, mining and washing of coal, textile industry, food manufacturing industry, and special equipment manufacturing. The Cronbach's Alpha reliability test was conducted, and the overall Cronbach's Alpha value for the model is 0.744, indicating a 74% reli-ability rate. Based on the literature review, a model with a Cronbach's Alpha value of over 0.50 can be considered for analysis. The text appears to be correct as it is. The Cronbach's Alpha reliability test was conducted, and the overall Cronbach's Alpha value for the model is 0.744, indicating a 74% reliability rate. Based on the literature review, a model with a Cronbach's Alpha value of over 0.50 can be considered for analysis.

Fungal decomposition of chicken-feather waste in submerged and solid-state fermentation.

Poultry industry is expanding rapidly and producing million tons of feather waste annually. Massive production of keratinaceous byproducts in the form of industrial wastes throughout the world necessitates its justified utilization. Chemical treatment of keratin waste is proclaimed as an eco-destructive approach by various researchers since it generates secondary pollutants. Keratinase released by a variety of microbes (bacteria and fungi) can be used for the effective treatment of keratin waste. Microbial degradation of keratin waste is an emerging and eco-friendly approach and offers dual benefits, i.e., treatment of recalcitrant pollutant (keratin) and procurement of a commercially important enzyme (keratinase). This study involves the isolation, characterization, and potential utility of fungal species for the degradation of chicken-feather waste through submerged and solid-state fermentation. The isolated fungus was identified and characterized as Aspergillus (A.) flavus. In a trial of 30 days, it was appeared that 74 and 8% feather weight was reduced through sub-merged and solid-state fermentation, respectively by A. flavus. The pH of the growth media in submerged fermentation was changed from 4.8 to 8.35. The exploited application of keratinolytic microbes is, therefore, recommended for the treatment of keratinaceous wastes to achieve dual benefits of remediation.

Multi-Sectoral Partnership for Waste Management Evaluation and Awards Recognition in Higher Education

Waste management is an important part to achieve green and sustainable campus. This study aims to evaluate waste management implementation in higher education. The methodology used in this study is a cross sectional with a non-probabilistic sampling. Data were collected using a well-structured evaluation instrument through an online focus group discussion, document review and evidence of implementation. The evaluation instrument consists of 10 elements: waste management policy, resource availability, waste segregation, waste collection, temporary waste storage, handling of general and hazardous waste, personal protective equipment (PPE), waste segregation awareness educational program, and evaluation on waste management. There were 15 faculties/schools/program were participated. Data was analysed using univariate analysis, radar plot representation, Box and Whiskers plot analysis. The level of waste management implementation amongst faculties /schools/program was varied between 52% to 98%. Higher education needs to evaluate waste management implementation and established a systematic environmental awareness program to achieve sustainability development goals (SDGs). The mean score ranking from highest to lowest level: personal protective equipment (5.6) to evaluation of waste management implementation (3.2). Indeed, to ensure a comprehensive general waste management, it was suggested that higher education need to build a centralized waste collection facility, a chemical waste treatment and competence personnel for handling laboratory waste.

Removal of Fluoride from Phosphogypsum Leaching Solution with Phosphate Tailing Based Layered Double Hydroxides: Kinetics and Equilibrium Isotherms

In this work, ternary and quaternary layered double oxides (PTB-LDO3 and PTB-LDO4) based on phosphate tailings were synthesized by the coprecipitation method. The as-prepared samples were characterized and applied to remove fluorine ions from a phosphogypsum leaching solution. The results indicated that both the precursor of PTB-LDO3 and PTB-LDO4 showed a layered structure with characteristic diffraction peaks of hydrotalcite. Compared with PTB-LDO4, PTB-LDO3 exhibited better adsorption performance at pH 5–6 and a dosage of 0.04 mg L−1. The adsorption kinetics results revealed that the adsorption of fluorine by PTB-LDO3 and PTB-LDO4 reached the adsorption equilibrium in about 3 h, and followed the pseudo-second-order model. The adsorption data could be fitted better with the Langmuir isotherm with the maximum adsorption amounts of 26.03 mg g−1 and 15.66 mg g−1 for PTB-LDO3 and PTB-LDO4, respectively. The adsorption of fluorine by PTB-LDO3 and PTB-LDO4 were both spontaneous and exothermic, and exhibited excellent reusability and stability. This study provides a possibility for the combined treatment of phosphorus chemical solid waste (phosphorus tailings) and phosphorus chemical wastewater (phosphogypsum leaching liquid).

Bioremediation Studies on Melanoidin Containing Distillery Spent Wash by Using Leuconostoc mesenteroides

Melanoidins are the natural condensation products present in distillery spent wash. It is the result of Millard reaction which occurs between glucose and glycine. From environmental aspects, melanoidins are very important because of the complex structure and caliginous colour and objectionable odour, which can cause damage to the surroundings. All these characteristics of melanoidin modify the photosynthetic activity of plants, reduce the dissolved oxygen of aquatic ecosystem, soil fertility is affected to a large extent, and it also slows down the sprouting of seeds. Bioremediation is an environmentally friendly technology for the treatment of chemical and hazardous waste. Bacteria from the nearby contaminated soil have a high potential to convert complex bioorganic substances to simpler absorbable form. With reference to this utilization of bacteria, Leuconostoc mesenteroides is an economical technology for the treatment of contaminated water having melanoidin. After treatment, the distillery spent wash was tested by using the analytical techniques as spectrophotometry, modified spectroscopy as Fourier-transform infrared (FTIR), chromatography with high performance i.e. (HPLC). In the present research paper, the results of above-mentioned techniques helped to make conclusions, as distillery spent wash polluted site contains a novel microorganism, which would be effective for the decolourisation as well as degradation of distillery spent wash. Application of Leuconostoc mesenteroids showed 40% distillery spent wash which contains melanoidin. Thus, the use of this novel microorganism in the field of environmental biotechnology will be an effective way to solve the biggest problem of water and soil pollution.

Zinc Compounds Obtained from the Karatau Phosphorites and Removal of Paraffins from Petroleum Products Using Synthesized Carbon Nanosorbents Containing Zinc

This paper describes an environmentally friendly and low-waste process that helps produce zinc-containing nanosorbents by processing phosphorite material. Compositional analysis of phosphorites showed that the impurities and magnesium contained in the Karatau ores (the latter is found in the form of dolomite) could make the direct processing of these ores much more complicated. A new safe and cost-effective technique has been developed for extraction of transition and rare elements. The samples obtained were studied on an Agilent 4200 MP-AES unit using atomic emission spectroscopy. The paperalso desc ribes a technique that uses recovered rare earth and transition elements to make nanocatalysts. These studies are of great scientific and practical interest as more research is necessary to better understand the adsorption of zinc ions on the nanosorbent surface. Chromatographic analysis of the obtained samples was carried out on a Perkin-Elmer AutoSystem LX gas chromatograph. The CN-CVD-100 method and a carbon nanotube were used for the absorption of free carbon atoms on the surface of the recovered compounds. The synthesized reagents are finely dispersed nanosorbents with a self-expressed structure. Studies have been carried out that looked at using the synthesized samples to reduce the paraffin content in petroleum products. The percent concentration of paraffins in oil was analyzed on a gas chromatograph. It was found that nanosorbents do have an effect on the oil composition as nanoparticles tend to quickly absorb impurities contained in the water and thus actively interact when the surface layers come into contact. With the help of experiments, it is shown that the zinc-containing nanosorbent synthesized following the proposed technique can be used for treatment of liquid chemical and petrochemical waste and wastewater. The use of zinc-containing nanosorbents as a special class of nanoparticles is a rather promising area.Contributors to this research work include E. Atenov, a doctoral student at the M. Kh. Dulati Taraz Regional University in Taraz, Republic of Kazakhstan.

Composite membranes with ultrathin and conformal passivation for universal microfiltration compatible with organic solvents

The development of porous membranes with excellent solvent resistances is an important technical task in relation to environmental and energy issues, including chemical waste treatment in the semiconductor industry. However, common polymer membranes, except for Teflon-based membranes, do not guarantee universal resistance to various organic solvents. In this study, a universal strategy is proposed to improve the solvent resistances of polymeric porous membranes through conformal passivation of ultrathin metal oxide layers via atomic layer deposition. Conformal ZnO shells with a thickness below ∼62 nm can significantly improve the inherently low resistances of nitrocellulose, polyethersulfone, and polycarbonate membranes to organic solvents without significantly degrading the flux. Although the polymer core is gradually dissolved by the organic solvent penetrating through the native cracks of the ZnO shell as the time of exposure to the organic solvent increases, the rigid porous network composed of hollow ZnO can well maintain its monolithic form for more than 1 week. Thus, it is possible to effectively filter pollen grains and heavy metal microparticles dispersed in harsh organic solvents without expensive Teflon-based membranes. This study opens new opportunities for selection of organic solvent-compatible membranes for microfiltration.

Estimation Complete Combustion Coefficient in Rotary Kilns

This paper presents a model-based analysis of variability of thermodynamic and chemical parameters in a rotary kiln (RK) during thermal treatment of animal waste. The core process of chemical treatment of waste takes place in RKs; the process involves heating, gasification and partial combustion of the waste. Control over these parameters, and especially the level of complete combustion, determines the quality and efficiency of the process. In operational practice, control and analysis of the variability of process parameters is complicated by the high degree of simultaneity of individual transformations, random disruptions of the process and metrological difficulties resulting from high temperature and chemical activity of the materials being processed. The purpose of preparing the model was to obtain a tool for predicting variability of selected process parameters. By definition, model calculations assume no influence of disturbances on output values, which makes it possible to acquire accurate results that can be compared with corresponding empirically obtained data. The result of the analyses conducted is a theoretical model of the analysed process and a graphical presentation of the calculation results in the form of graphs and charts. A formula for calculating the level of complete combustion and the results of calculation of this index on the basis of empirical data from an industrial waste incineration plant are also presented herein. The presented model is a useful tool providing an insight into interdependencies between selected process parameters and facilitating design of corrective actions oriented towards process optimisation.

Sustainable processes for treatment and management of seafood solid waste

Seafood processing is an important economical activity worldwide and is an integral part of the food chain system. However, their processing results in solid waste generation whose disposal and management is a serious concern. Proteins, amino acids, lipids with high amounts of polyunsaturated fatty acids (PUFA), carotenoids, and minerals are abundant in the discards, effluents, and by-catch of seafood processing waste. As a result, it causes nutritional loss and poses major environmental risks. To solve the issues, it is critical that the waste be exposed to secondary processing and valorization for recovery of value added products. Although chemical waste treatment technologies are available, the majority of these procedures have inherent flaws. Biological solutions, on the other hand, are safe, efficacious, and ecologically friendly while maintaining the intrinsic bioactivities after waste conversion. Microbial fermentation or the actions of exogenously introduced enzymes on waste components are used in most bioconversion processes. Algal biotechnology has recently developed unique technologies for biotransformation of nutrients, which may be employed as a feedstock for the recovery of important chemicals as well as biofuel. Bioconversion methods combined with a bio-refinery strategy offer the potential to enable environmentally-friendly and cost-effective seafood waste management. The refinement of these wastes through sustainable bioprocessing interventions can give rise to various circular bioeconomies within the seafood processing sector. Moreover, a techno-economic perspective on the developed solid waste processing lines and its subsequent environmental impact could facilitate commercialization. This review aims to provide a comprehensive view and critical analysis of the recent updates in seafood waste processing in terms of bioconversion processes and byproduct development. Various case studies on circular bioeconomy formulated on seafood processing waste along with techno-economic feasibility for the possible development of sustainable seafood biorefineries have also been discussed.

Chemical Treatment of Bio-Derived Industrial Waste Filled Recycled Low-Density Polyethylene: A Comparative Evaluation.

The search for renewable alternatives for petroleum products that can be used in industrial applications is increasing. Each year, several tons of bio-derived industrial waste is produced and most of it is burned or placed in landfills. Olive pits (OP) have unique characteristics such as abundance, renewability, and biodegradability, which can be utilized to develop new types of biocomposites. One of the most promising uses of OP is that they can reinforce the mechanical properties of polymeric biocomposites. This study describes the preparation of recycled low-density polyethylene (rLDPE) that is filled with OP flour (10, 20, 30, and 40 wt.%) using a twin-screw extruder. The effects of the chemical treatment of the OP surface (sodium hydroxide (NaOH) and dimethyl sulfoxide (DMSO)) on the bio-filler/polymer compatibility along with the produced composite’s chemical, physical, mechanical, and thermal properties have been explored. Overall, the reinforced composites that were obtained with alkali-treated OP have better biocomposite properties. This indicates an improved compatibility between the bio-filler and matrix. The results are promising in terms of using OP flour in developing green composites.

Development of environmental education concepts concerning chemical waste management and treatment: the training experience of undergraduate students

It is essential to develop a safety culture with the participation of university teachers and students in actions and studies that can contribute to safer and more sustainable practices in academic laboratories. The present work analyzes the potential of a training program to raise awareness and establish environmental education and green chemistry concepts concerning procedures for the management and treatment of chemical waste generated in experimental classes. This is a qualitative case study providing a critical perspective of environmental education. The training activity, lasting 45 minutes, was conducted with 66 students entering Chemistry courses at a Brazilian public university. Data collection was carried out using an initial questionnaire to identify the students’ prior knowledge, and a final one applied after the training period. The questionnaires contained open questions and closed questions with a Likert-type scale. The results showed that the training activity contributed to the students’ understanding of the concepts, procedures, and attitudes related to the management and treatment of chemical waste, including the interrelations among the environmental, social, and economic impacts of waste management, the importance of correct separation and storage of residues for disposal using different types of treatment, the civil liability of the academic community for the residues generated, and how the 3Rs principles can favor sustainable practices in the academic context.

Physical, chemical, and biological treatment of chemical waste from teaching laboratories at Universidad Nacional, Costa Rica

Herein, we report the physical, chemical, and biological treatment of wastewater generated in the teaching laboratories at Universidad Nacional, Costa Rica. Initial physicochemical treatment included neutralization and coagulation-flocculation, followed by a biological treatment with fungi (Aspergillus sp. and Penicillium dipodomyicola) or bacterias, the latter were isolated from the sludge from the campus’ wastewater treatment plant and the greywater collection tank at the School of Chemistry. The samples’ pH prior to treatment was ≤ 2, while COD ranged between 3000 and 30 000 mg/L. Gas chromatography-mass spectra analysis indicated the presence of 55 organic compounds in the wastewater, some of which reached undetectable concentrations after treatment. The fungi and the bacterial strain removed up to 50% of the substances, while the toxicity decreased with respect to time of exposure to the treatment. Results support the potential use of these microorganisms as bioremediators. Although the organic compounds were partially removed, the treated wastewater exhibited high toxicity for Daphnia magna (water flea). Further experiments with longer treatment times or other strains might be needed for effective removal of pollutants.

Chemical Treatment of Liquid Waste Generated from Leather Tannery Industry by Using Alum as Coagulant Material

The tannery industry generally produces trivalent chromium waste (Cr3 +) and hexavalent chromium (Cr6 +). This waste before being released into the environment must meet quality standards according to KEPMENLH no.51 / MENLH / 10/1995 concerning liquid quality standards for industrial activities which says the maximum total chromium content is 0.6 ppm. This study aims to reduce the levels of Chromium in waste produced by the leather tanning industry by using alum coagulants. This research uses simulation waste which is made based on the results of BPPT analysis of waste in the leather tanning industry in Tangerang city, namely CV "Lengtat Tangerang Leather". The method used in this research is coagulation-flocculation with alum as a coagulant and lime as an alum reaction assistant in the form of hydroxide ions. The parameters observed in this study were the pH adjustment and the ratio of alum mass to lime mass. From the results of the study it was found that the decrease in the best chromium content for Cr + 3 occurred at a ratio of 5 and pH 8.2 which resulted in a chromium content of 0.0076 ppm with a decrease in percentage of 99.95%. As for the Cr6 + test, at a ratio of 3 and pH 6.4 the chromium content showed a value of 0.4110 ppm. The lowest chromium level occurs at a ratio of 5 and pH of 5.8 which results in a chromium level of 0.3341 ppm with a decrease percentage of 56.61%.

In vitro antioxidant properties and digestibility of chicken feather protein hydrolysates

The in vitro antioxidant property and digestibility of chicken feather protein hydrolysate (CFPH) were evaluated in this study. The antioxidant property of CFPH obtained following chemical treatment of chicken feather waste involving precipitation with various acids (H2SO4, HNO3, TCA and HCl) was determined via its scavenging action against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, iron reduction power and metal ion chelating activity. Data obtained showed that CFPHHNO3 had the highest DPPH scavenging activity while CFPHTCA exhibited the highest ferric (Fe3+) reduction potential. On the other hand, CFPHTCA, CFPHH2SO4 and CFPHHNO3 showed a similar capacity for Fe2+ -chelation compared to CFPHH2SO4 with the least chelating potential. The in vitro protein digestibility of the CFPH of the various acids ranged from 62.30±1.0% (CFPHHNO3) to 73.10±1.3% (CFPHTCA) and were significantly (p < 0.05) higher compared to the raw feather (23.80±0.5%). These results indicate that CFPH may be useful as antioxidants in animal feed formulations and also serve as additional source of essential nutrients in feeds.