Engineering and Physical Bases of Development and Creation of Plasmochemical Reactors for Mobile Facilities for Medical Waste Disposal

This paper presents the results of the development and creation of plasma-chemical reactors for mobile and stationary installations for the destruction and disposal of solid, liquid, gaseous and mixed medical waste based on the domestic plasma generator PUN-1, with air as the plasma-forming gas. The design and principle of operation of plasma-chemical reactors installed on mobile experimental and industrial plants “Plazmon-1,2,3”, as well as the main features of the plasma waste disposal process are described.

The Adsorption of Pb(II)Using Silica Gel Synthesized from Chemical Bottle Waste:Optimization Using Box-Behnken Design

The adsorption of Pb(II)on silica gel synthesized from chemical glass bottle waste has been studied.The effect of independent variables(adsorbent dose,initial concentration of Pb(II),contact time,and pH)on the Pb(II)removal from water was evaluated and optimized using the Response Surface Methodology(RSM).Under optimized conditions(adsorbent dose:20 mg;contact time:30 min;initial Pb(II)concentration:120 mg.L^(−1);and pH:8),the removal of Pb(II)was 99.77%.The adsorption equilibrium data obtained from the batch experiment were investigated using different isotherm models.The Langmuir isotherm model fits the experimental data.This shows that the surface of the silica gel synthesized from chemical bottles waste was covered by a Pb(II)monolayer.XRF analysis showed that the synthesized silica gel had a SiO_(2) content of 75.63%.Amorphous silica was observed from XRD analysis.SEM-EDX characterization showed that Pb was adsorbed on the silica gel surface.SEM analysis showed that silica gel has irregular particles with a surface area of 297.08 m2.g^(−1) with a pore radius of 15.74 nm calculated from BET analysis.

A Report on Identification, Segregation, Disposal and Reduction of Chemical Wastes

The accumulation of generated chemical wastes posed a serious problem for the UP College of Pharmacy. The faculty from the Department of Pharmaceutical Chemistry devised a scheme for the identification and segregation of the chemical wastes and created a system for proper disposal of future chemical wastes. There were a total of 1,142 of accumulated chemical waste bottles, 804 of which were subjected to identification and segregation procedures. The wastes were preliminarily tested for its solubility/miscibility in water and acidity or basicity. The identification was done by qualitative tests for cyanide, sulfide, halogenated, non-halogenated, oxidizing, nitro, and heavy metal compounds. The final segregation was based on the presence of the most hazardous component or on pH and water-miscibility. The Department then developed and implemented a scheme for the proper disposal of the chemical wastes generated in laboratory experiments done in the College. Laboratory experiments were also modified to use less toxic and less amounts of chemicals.

Biochemical Methane Potential of Food Wastes from Akouedo Landfill, Côte d’Ivoire

The determination of biochemical methane potential (BMP) is very important for the valorization of food wastes. This study is focused on the evaluation of the theoretical methane production from chemical oxygen demand (COD) of some food wastes, coming out Akouedo landfill. Almost all of the considered samples exhibited methane theoretical yields equal to about 402.5 - 507.8 mLCH4/gVS. These results indicate the suitability of all the studied food wastes from Akouedo landfill to be converted into energy.

Chemical speciation and mobility of heavy metals in municipal solid waste incinerator fly ash

Chemical speciation is a significant factor that governs the toxicity and mobility of heavy metals in municipal solid waste incinerator fly ash. Sequential extraction procedure is applied to fractionate heavy metals(Pb, Zn, Cd, Cu, and Cr) into five defined groups: exchangeable, carbonate, Fe-Mn oxide, organic, and residual fractions. The mobility of heavy metals is also investigated with the aid of toxicity characteristic leaching procedure. In the fly ash sample, Pb is primarily presented in the carbonate(51%) and exchangeable(20%) fractions; Cd and Zn mainly exist as the exchangeable(83% and 49% respectively); Cu is mostly contained in the last three fractions(totally 87%); and Cr is mainly contained in the residual fraction(62%). Pb, Zn and Cd showed the high mobility in the investigation, thus might be of risk to the natural environment when municipal solid waste incinerator fly ash is landfilled or reutilized.

Effects of bioleaching on the mechanical and chemical properties of waste rocks

Bioleaching processes cause dramatic changes in the mechanical and chemical properties of waste rocks, and play an important role in metal recovery and dump stability. This study focused on the characteristics of waste rocks subjected to bioleaching. A series of ex- periments were conducted to investigate the evolution of rock properties during the bioleaching process. Mechanical behaviors of the leached waste rocks, such as failure patterns, normal stress, shear strength, and cohesion were determined through mechanical tests. The results of SEM imaging show considerable differences in the surface morphology of leached rocks located at different parts of the dump. The minera- logical content of the leached rocks reflects the extent of dissolution and precipitation during bioleaching. The dump porosity and rock size change under the effect of dissolution, precipitation, and clay transportation. The particle size of the leached rocks decreased due to the loss of rock integrity and the conversion of dry precipitation into fine particles.

Chemicals,Energy,and Biomaterials from Agricultural Waste Resources in South China

Owing to its subtropical or tropical environment and climate,South China is home to unique agricultural crops such as sugar cane,pineapple,banana,cassava,and rice,which generate a large amount of lignocellulosic agricultural wastes during agricultural as well as associated industrial processing.The efficient utilization of these wastes will have a significant impact on the economy and sustainable development of South China.This paper reviews the research investigations conducted both in China and elsewhere on the conversion of wastes from these subtropical or tropical agricultural crops into useful chemicals,energy,and biomaterials.The goal of this paper is to promote and summarize the extensive investigations on these agricultural wastes for the development of biorefinery.

Chemical constituents and antioxidant activities of waste liquid extract from Apostichopus japonicus Selenka processing

Apostichopus japonicus Selenka is an ideal tonic food that is used traditionally in many Asian countries, and it contains many bioactive substances, such as antioxidant, antimicrobial, and anticancer materials. To convert waste liquid generated during production into a useful resource, extract from waste liquid was isolated by column chromatography and studied by the pyrogallol autoxidation and 1,10-phenanthroline-Fe^2＋ oxidation methods. Results show that the extract scavenged about 91% of the superoxide anion radical at a concentration of 1.4 mg/mL and 24% of the hydroxyl radical at 3.3 mg/mL. Four compounds were isolated and identified from the extract： 2,4-dihydroxy-5-methyl-1,3-azine; 2,4-dihydroxy- 1,3-diazine; 3-O-β-D-quinovopranosyl-（1→2）-4-O-sodium sulfate-β-D-xylopranosyl]-holosta-9（11）-ene313,12β,17α-triol; and 24-ethyl-5α-cholesta-7-ene-3β-O-β-D-xylopyranoside. All of these compounds are known in A. japonicus, and were found in the waste liquid for the first time.

Ca-and Mg-rich waste as high active carrier for chemical looping gasification of biomass

Chemical looping gasification(CLG)is a promising technology for high-quality syngas production.One key issue to successful CLG is the selection of high-performance oxygen carrier.In this study,several Ca-and Mg-rich steelmaking wastes from steel industry,such as blast furnace slag(BF slag),blast furnace dust(BF dust)and Linz-Donawitz converter slag(LD slag),were used as oxygen carriers in chemical looping gasification of biomass.The results showed that the reducibility of Ca-and Mg-rich waste,especially LD slag and BF dust,was superior to that of hematite.Considering long-term operation,the cyclic stability of steelmaking waste was tested.BF dust showed a poor stability,while the other carrier(hematite,BF slag or LD slag)presented an excellent stability during multiple redox cycles in spite of partial sintering and agglomeration.Moreover,the effects of supply oxygen coefficient(O/B ratio)and reaction temperature on CLG of biomass were investigated.The results revealed that Ca-and Mg-rich waste exhibited a higher syngas production compared to hematite.The higher performance could be attributed to the improved reduction rate of Fe2O3 and gasification rate of biomass by Ca or Mg in steelmaking waste.In addition,LD slag exhibited the higher gas value at the O/B ratio of 1 at 900℃.As a consequence,LD slag was an appropriate oxygen carrier for CLG of biomass in terms of perfect reducibility,superior cyclic stability and high reactivity.

Modelling thermo-hydro-mechano-chemical interactions for nuclear waste disposal

A fully coupled thermo-hydro-mechano-chemical（THMC） formulation is described in this paper.Special attention is paid to phenomena likely to be encountered in clay barriers used as engineered barriers in the disposal of nuclear radioactive waste.The types of processes considered in the chemical formulation include hydrolysis,complex formation,oxidation/reduction reactions,acid/base reactions,precipitation/dissolution of minerals and cation exchange.Both kinetics-and equilibrium-controlled reactions are incorporated.The formulation is implemented in a numerical code.An application is presented concerning the performance of a large-scale in-situ heating test simulating high-level radioactive waste repository conditions.

Rheological and physicochemical characteristics of asphalt mastics incorporating lime kiln dust and dolomite powder as sustainable fillers

The filler-bitumen interaction mechanism is one of the most essential phases for comprehending the asphalt mixture's performance.However,despite numerous studies,in-depth knowledge of filler-bitumen reciprocity at a microscale level is yet to be ascertained.The goal of this research is to gain a better understanding of the fillerbitumen microscale interaction in terms of the synergy and coaction between the physicochemical and rheological performance of mastics due to filler inclusions.The rheological properties of two sustainable mastics,dolomite powder(DP)and lime kiln dust(LKD),together with a neat PEN 60/70 binder,were analysed based on a temperature sweep at elevated temperature conditions.Meanwhile,frequency sweep and multiple stress creep recovery(MSCR)tests were also conducted at pavement serviceability temperature using the dynamic shear rheometer(DSR).Physicochemical tests using a scanning electron microscope(SEM)and energy dispersive X-rays(EDX)were conducted to analyse the impact of parameters such as particle shape,grain size,texture,and chemical compositions.The DSR test results showcased how the incorporation of fillers in asphalt binder considerably improved the performance of the binder in terms of rutting and fatigue.Likewise,its strain and nonrecoverable compliance parameters were substantially reduced at higher filler and binder concentrations.Physical filler attributes of low rigden voids(R.V),high fineness modulus(FM),and high specific surface area(SSA)led to greater interfacial stiffness and elasticity in LKD mastics compared to DP mastics at different loading frequencies and temperature levels.The SEM/EDX results also indicated that the elemental calcium and carbon composition of each filler component,together with its grain morphology,strongly influenced its rheological performance.

Recycling of waste foundry sands by chemical washing method

This study aims to remove the metals(inorganic and heavy metals) in waste foundry sand(WFS)via chemical washing method. Washed waste foundry sand(WWFS) samples were obtained by using triptych washing successively with 5 M HCl, 5 M H_2SO_4 and 5 M NaOH solutions. Analysis on functional groups,micropores, heavy metals,and inorganic components of WFS and WWFS was carried out by using FT-IR, SEM and XRF. Results show that the concentration values of some inorganic components such as Ca, Fe, Mg, S were decreased, and the maximum removal percentage of these inorganic components are 47%, 19%, 32%, and 8%,respectively. The concentration values for each of the heavy metals of WWFS are below of limit values given in App-3 List of Regulation on General Principles of Waste Management. The removal percentages of Pb, As and Zn elements are 100%, 71%, and 40%, respectively. The findings of this research suggest that WWFS can be used in more applications due to its ability to remove heavy metals and some other inorganic components.

Issue of Managing Waste Computer Equipment in Conakry City (Republic of Guinea)

The digitization of administrative activities is a technique that not only optimizes resources, but also professionalizes the working methods of public and private services. This dematerialization process involves technologies based on computer equipment, which, after use, becomes cumbersome waste. The aim targeted consisted of taking stock of the management of waste computer equipment imported into the Republic of Guinea, with a view of proposing a mode of environmentally sustainable management methods in a short time. To achieve this, the data was collected through investigation methods (observations, interviews, and questionnaires). This study reveals an excess of imports of electrical and electronic equipment in general, and computer equipment in particular, over the last ten years (2009-2019), With an import rate ranging from 4.03 to 54.45%. This study demonstrated the different ways in which computer and electronic equipment of all kinds are managed, with her failings. This study demonstrated the different ways in which computer and electronic equipment of all kinds are managed, as well as their failings. For this purpose, the different ways in which electronic waste is managed by different users were identified as storage, recycling, or rejection into nature or at waste storage points, often mixed with household waste. Companies specializing in the management of this type of waste and the presence of a certain number of regulatory texts almost do not exist. One company is only for the entire country but unknown to the majority of users.

Troubleshooting and Optimization of High-Strength Inhibitory Chemical Wastewater Treatment Process

Wastewaters from the chemical industry are usually of high-strength and may contain minor inhibitory and recalcitrant organics that are at times not readily identifiable. This paper describes the experience of a biological waste water treatment plant （WWTP） processing a COD concentration of 43000 mg·L^-1 wastewater from an oxochemical manufacturing plant. Stage improvements of the plant process by dilution of the inhibitory influent using other chemical wastewater streams resulting in a synergistic process effect, and removal of inhibitory organics by phase separation via acidification, effectively achieved process optimization producing a high quality effluent. In particular, the COD removal efficiency of granular sludge based anaerobic reactors increased from 56% to 90%. The final effluent COD decreased from 250mg·L^-1 to 50mg·L^-1, consistently meeting the COD concentration of 100 mg·L^-1 regulatory discharge limit. The success of the process enhancements supports the hypothesis that long-chain quaternary carboxylic acids act as substrate inhibitors in the biological process.

Long-Term Effect of Industrial Waste Water Irrigation on Soil Chemical Properties

A laboratory experiment was conducted in Soil Science Division of BRRI during 2011 aimed to determine the vertical distribution of soil chemical properties under long-term industrial waste water irrigated rice field. Waste water irrigated rice field seemed to create some differences in soil pH profile. The pHW and pHKCl in all soil depth was higher with waste water irrigated rice field. The surface charge of both the soils was considerably negative. Waste water irrigated rice field developed more negative charges in soils. Irrigation with waste water increased Electrical Conductivity （EC） in rice soils profile. The organic carbon content （%） started to decrease sharply with the increase in soil depth. Organic carbon content was higher with waste water irrigated rice soils Total nitrogen （%） was high with underground water irrigated rice soils in surface but at deeper, total N was similar in both soils. Olsen P （mg/kg） was higher with underground water irrigated soil at 0-5 cm depth but at 5-100 cm soils profile, it was higher with waste water irrigated rice soils. Micronutrients （Zn, Fe, Cu and Mn） and heavy metals （Pb, Cd, Ni and Cr） in soils were increased significantly through irrigation with waste water in rice-rice cropping pattern.

Short Term Effects of Olive Mill Waste Water on Soil Chemical Properties under Semi Arid Mediterranean Conditions

The aim of this work is to assess the short term effect of OMWW （olive mill waste water） application on chemical and biological soil properties. A field experiment was carried out in southern Tunisia. OMWW application was done at rates equivalent to 0, 15, 30 and 45 m^3/ha. Results showed that increasing rates of OMWW enhance the soil fertility due to its richness in organic matter such as N and P. A rapid increase of microbial biomass （during 14 days of incubation） of OMWW amended soils occurred. However, a high increase in salinity values and phenolic compounds concentrations was observed during this experiment.

Studying the Utilization of Plastic Waste by Chemical Recycling Method

The rapid increase in the use of plastic materials in the recent years led to the accumulation of excessive amounts of plastic waste. The so-called thermoplastics such as PE, PP, PS, PVC and PET as well as materials that are derived from these are the type of plastic that is most used and consequently creates most of the waste. In this study, the original and waste forms of PE and PP plastic types have been chosen for thermal and catalytic degradation. As process parameter, 410oC - 450oC temperature interval and 600 mL/min constant flow rate nitrogen gas have been chosen as the carrier gas and the reaction time was considered to be 90 minutes for all experiments. Liquid products collected in experiments were separated by means of fractioned distillation process. For purposes of determining product distribution, the fractions, which were separated by distillation, were diluted in an appropriate solution for analysis of GC/MS. In the study conducted, it has been observed that the liquid product distribution obtained mainly consists of a mixture of saturated and unsaturated (heptane, heptane, octane, nonane, dodecane, etc.) hydrocarbons.

Physico-Chemical and Microbial Quality of Locally Composted and Imported Green Waste Composts in Oman

In this work the physical, chemical and microbial properties of four locally composted green waste composts (GWCs) namely Almukhasib, Growers, Plantex, and Super along with four imported GWC (Florabella, Mikskaar, Potgrond, and Shamrock) were studied to evaluate the quality of these composts with the acceptable standards. All composts showed normal physical properties, except the bad smell from sulfur reducing bacteria in Almukhasib, light brown color Plantex and one viable weed seed in Shamrock compost. The germination indexes of the composts comparable to the standard (90%) were 100% for Mikskaar, followed by Shamrock (92%), Florabella (97), Potgrond (95%), Plantex (98%), Growers (77%), and 5% for both Super and Almukhasib. The physical and chemical properties vary considerably as follows: pH 3 - 10.5, 5.1 - 6.5 (standard 5 - 8), electrical conductivity (EC) 0.4 - 10.2 mS·cm-1, 0.8 - 1.8 mS·cm-1(standard 0.0 - 4.0 mS·cm-1), moisture content (MC%) 29% - 43.7%, 64% - 74% (standard 35% - 60%) and water holding capacity (WHC%) 92% - 200% and 400% - 800% for the locally produced and imported composts, respectively. Wide ranges in the chemical properties were expressed as ammonia concentration 512.4 - 1640.1 mg·kg-1, 459.4 - 656.5 mg·kg-1(standard -1), organic matter 17% - 67.6%, and 53.3% - 66.2% (standard 35%) for the locally composted and imported composts, respectively. The concentrations of the heavy metals (Zn, Ni, Pb, Hg, As, Cd, and Cr) were lower than the recommended levels. The average of the bacterial colony forming unit per gram of locally produced and imported composts ranged between 260 - 1740 CFU/g and 330 - 2870 CFU/g, whereas the fungal CFU were 10 - 2800 CFU/g and 27 - 1800 CFU/g, respectively. The most probable number (MPN) for coliform bacteria was 43 - 1100 CFU/g for locally produced composts, and 23 - 480 CFU/g for the imported composts. Therefore, these composts can not be used directly without effective treatment as substrate for plant growth, soil amendment and as biofertilizer.

Synergistic effects of chemical additives and mature compost on reducing H_2S emission during kitchen waste composting

Additives could improve composting performance and reduce gaseous emission,but few studies have explored the synergistic of additives on H_(2)S emission and compost maturity.This research aims to make an investigation about the effects of chemical additives and mature compost on H_(2)S emission and compost maturity of kitchen waste composting.The results showed that additives increased the germination index value and H_(2)S emission reduction over 15 days and the treatment with both chemical additives and mature compost achieved highest germination index value and H_(2)S emission reduction(85%).Except for the treatment with only chemical additives,the total sulfur content increased during the kitchen waste composting.The proportion of effective sulfur was higher with the addition of chemical additives,compared with other groups.The relative abundance of H_(2)S-formation bacterial(Desulfovibrio)was reduced and the relative abundance of bacterial(Pseudomonas and Paracoccus),which could convert sulfur-containing substances and H_(2)S to sulfate was improved with additives.In the composting process with both chemical additives and mature compost,the relative abundance of Desulfovibrio was lowest,while the relative abundance of Pseudomonas and Paracoccus was highest.Taken together,the chemical additives and mature compost achieved H_(2)S emission reduction by regulating the dynamics of microbial community.

Rapid chemical recycling of waste polyester plastics catalyzed by recyclable catalyst

Waste plastics are serious environmental threats due to their low degradability and low recycling rate.Rapid and efficient waste plastics recycling technologies are urgently demanded for a sustainable future.Herein,we report a rapid,closed-loop,and streamlined process to convert polyesters such as poly(ethylene terephthalate)(PET)back to its purified monomers.Using trifluoromethanesulfonic acid or metal triflates as the recyclable catalyst,polyesters such as PET can be completely depolymerized by simple carboxylic acids within 1 h.By coupling this acidolysis with a subsequent hydrogenolysis process,the consumed carboxylic acid was recovered and the closed-loop of PET depolymerization could be established.All catalysts and depolymerization agents are fully recycled while only PET and hydrogen are consumed.