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Энэхүү судалгаагаар Завхан аймгийн Улиастай сумын хөрсний хүнд элементийн судалгааг хийсэн ба судалгааны хүрээнд өмнөх 2022 онуудын хөрсний дээжний шинжилгээнүүдтэй харьцуулж, бохирдлын индекс үнэлж, экологийн эрсдлийн үнэлгээг хийж гүйцэтгэлээ. Улиастай сумын нийт 20 цэгээс хөрсний дээж авч, SGS магадлан итгэмжлэгдсэн лабораторид 33 элементийг шинжилж, тэдгээрээс байгаль орчин, хүний эрүүл мэндэд хор хөнөөлтэй нөлөө бүхий 9 хүнд металлын(As, Cd, Co, Cr, Cu, Ni, Pb, V, Zn) агууламжийг Монгол Улсын стандарт болон олон улсын судалгаатай харьцуулан үнэлсэн. Шинжилгээний үр дүнд бүх дээжид хүнд металлын агууламж MNS 5850:2019 стандартын зөвшөөрөгдөх хэмжээнээс бага байсан боловч, гео-хуримтлалын индекс (Igeo) болон экологийн эрсдэлийн үнэлгээ (Er)-гээр зарим элементүүд нь “дундаас их”, “их хэмжээний” бохирдолтой байв. Ялангуяа хүнцэл (As) болон хар тугалга (Pb)-ын хувьд тодорхой цэгүүдэд экологийн эрсдэл нэмэгдэж буйг анхаарах шаардлагатай.Баяжуулагч хүчин зүйлийн (EF) үнэлгээгээр зарим металлууд (жишээлбэл, Cu, Zn, Ni) “дунд зэрэг”, “дунд зэргээс их” баяжуулалттай гарсан нь хүний үйл ажиллагаанаас үүдэлтэй бохирдлын эх үүсвэр болохыг илтгэж байна. Мөн авто засварын газар, уурын зуух, мах комбинатын орчмоос авсан хөрсөнд бохирдлын түвшин өндөр байгаа нь тухайн бүсэд хяналт, зохицуулалт сул байгааг харуулж байна. Нүүрс болон Үнсний шинжилгээний дүнгээс харахад галлагаанд хэрэглэж буй нүүрс нь шаталтын дараа хүнд элементийг агууламж нь өссөн үр дүнтэй харагдаж байна. Экологийн эрсдэлийн үнэлгээний хамгийн бага утга нь 5.54 буюу Авто засварын газарын ойролцоох хөрсний дээжинд гарсан байна. Судалгааны үр дүн нь Улиастай сумын хөрсөнд хүнд металлын бодит аюул одоогоор бага түвшинд байгаа ч, зарим бүсүүдэд хуримтлал нэмэгдэж, урт хугацаанд байгаль орчны тогтвортой байдалд нөлөөлж болзошгүйг харуулж байна.
Spent hydrodesulfurization (HDS) catalysts, produced in the petroleum refining process, are usually classified in hazardous solid waste. Recovery of valuable metals from spent HDS catalyst not only reduce substantially environmental risk but is an important way to alleviate global resource shortages for high-valuable metals. This study reviews numerous references regarding to recovery valuable metals from spent HDS catalyst in last decades, and divided current methods into three processes: pretreatment, oxidation-leaching, and separation-purification processes. Roasting and solvent washing usually emerge as primary methods in the pretreatment process, and effectively eliminate the surface oily substances and sulfur. Sodium salt roasting-leaching are considered as higher efficient among all leaching methods. The application of organic acid in the leaching can separate valuable metals selectively and simplify subsequent purification steps. In separation-purification processes, solvent extraction is still a standout method to isolate challenging metals such as Mo, W and V. However, the burgeoning field of ion imprinting technology exhibits the promising potential. Additionally, Random Forest and XGBoost model are used to analyze reported methods to recovery Mo and Ni and predict the key factor to regulate recovery efficiency. The results show that Mo recovery process is depended on the spent HDS characteristics and solid-liquid ratio in leaching process, while Ni recovery processes is depended on the roasting time and roasting temperature. Finally, serval specific industrial cases on recycling valuable metals from spent HDS were given, and found that sodium salt roasting-water leaching process was still frequent used in practical application due to its characteristics of high efficiency and low cost.
Abstract Spent hydrodesulfurization (HDS) catalysts were considered as a vital secondary resource for precious metals like Mo. The current pyrometallurgy and hydrometallurgy usually exhibits the characteristic of remarkable high energy consumption and high secondary pollutions. This study proposes an innovative technique to recycling MoO3 from spent HDS catalyst by sublimation process at high temperature, which has notable advantages of zero wastewater-generation and zero chemical reagent consumption. Notably, MoO3 recovery efficiency was improved remarkably with the introduction of water-vapor. About 99.33 % of MoO3 was recovered by heating spent HDS catalyst at 1100℃ for 2.5 h in water-vapor atmosphere with partial pressure of 101.33 kPa. The yielded MoO3 was tested with the purity of 99.94 % and exhibited the appearance of thin strips. Furthermore, the sublimation kinetic of MoO3 in air was adhered to a desorption model, while agreed with a non-desorption model in water-vapor atmosphere. Density Functional Theory (DFT) calculations revealed that -OH obtained by the dissociation of H2O molecules preferably combined with MoO3 and formed the volatile MoO3-OH, which was responsible for enhancing MoO3 sublimation efficiency significantly in water-vapor atmosphere. Economic analysis suggested that the direct cost of this method was 345 $/t, accounting for around 50 % compared to current roasting-leaching-purification methods.
Abstract Cement kiln co-processing has become a popular strategy for dealing with solid waste containing Cr(III) because hazardous Cr(III) can be incorporated into the cement matrix to reduce its leaching risk. However, whether Cr(III) can be transformed and leached from the cement matrix under extreme conditions remains unclear. This study demonstrates that even when Cr(III) is solidified and encapsulated by the cement matrix, it can undergo substantial oxidation into soluble Cr(VI) in case of low-intensity fire with temperatures range of 100–250°C. Approximately 43.8% of Cr(III) was oxidized into Cr(VI) when the cement matrix was fired at 250°C for 1 h, and CrO3 was identified as the predominant phase of Cr(VI). When the firing time was increased beyond 10 h,some CrO3 was reduced into Cr(III), and the combination of CrO3 and CaO occurred accompanied with the formation of CaCrO4. Based on the toxicity characteristic leaching procedure, the concentrations of Cr(VI) leached from the cement matrix samples fired at 200 and 250°C for 5 h exceeded the regulatory limit. The cumulative leaching amounts of Cr(VI) from the cement matrix samples fired at 200 and 250°C in EA NEN 7375:2004 tank tests were 1381 and 1369 mg/m2 respectively, far higher than the limit of 25 mg/m2. These substantial levels of Cr(VI) formation and release imply that Cr(III) solidified into cement materials may still pose environmental risks due to leaching in the event of a fire or other high-temperature situation. Keywords: Wildfire, Hexavalent chromium, Cement martials, Oxidation, Leaching risk
Abstract Thermal hydrolysis is becoming a crucial approach to enhance the level of sewage sludge resource utilization. Introducing additives became the dominant way to improve thermal hydrolysis efciency for sewage sludge, because elevating temperatures increased system energy consumption. Traditional additives like strong acids (e.g. vitriol) may lead to high overall operating costs for sludge thermal hydrolysis. This study proposed a new strategy to improve signifcantly the thermal hydrolysis efciency of sewage sludge by adding a new additive of tannic acid (TA). It was observed that TA facilitated the dissolution of organic matter during the thermal hydrolysis process of sewage sludge and promoted the conversion proportion of macromolecular organic matter into smaller molecular forms. The highest organic matter content (142% of the blank group) in the fltrate was achieved when the sewage sludge was treated at 175 °C for 45 min with the optimal TA dosage of 0.3 mmol/gTS. While the biodegradability of the fltrate was better (BOD5/COD was 62%) when the sewage sludge was treated at 175 °C for 60 min. The addition of TA can greatly reduce the temperature of sludge thermal hydrolysis (Decreased by 25 °C). The carbohydrate and VFAs were identifed as major contributors to the increase in dissolved organic matter content in the fltrate. Additionally, it was demonstrated that TA promoted N and P release from sewage sludge but inhibited NH3-N release. This study give a novel strategy to enhance the practical application potential for thermal hydrolysis of sewage sludge.
Монгол орны хувьд хот суурин газруудад хүн ам суурьших үйл явц ХХ зууны сүүлийн хагаст явагдаж эхэлсэн хэдий ч 1990 оны нийгмийн өөрчлөлттэй холбоотой зөв зохистой суурьшил, хүн амын нягтшилын бодлого алдагдсан. Олон хүн бөөгнөрөн суурьших байгалийн нөхцөл, нөөц багатай манай орны хувьд томоохон хот суурин газрууд ихэвчилэн томоохон голын хөндий, уулын ам хөндийн системд төвлөрсөн шинжтэй байгаа нь хүн амын төвлөрөлтэй уялдан техноген нөлөөлөлд хялбар өртөх, байгаль орчны тэнцэл алдагдах үндсэн шалтгаан болж байна. Энэ судалгааны ажлын хүрээнд баруун бүсийн хөгжлийн томоохон төв болох Завхан аймгийн Улиастай хотын орчны бохирдол, антропогени нөлөөллийг тодорхойлох зорилгын хүрээнд хөрсний хүнд металлаас хүрээлэн буй орчин болон хүний эрүүл мэндэд үзүүлэх эрсдлиийн үнэлгээг тооцоолох, Улаанбаатар хотын хөрсний судалгааны үр дүнг харьцуулсан судалгааг хийж гүйцэтгэсэн. Улиастай сумын төвийн бүсд газар ашиглалтын эрчим, төрөл, нягтшилтай уялдуулан хөрсний 38 цэгээс холбогдох стандартын дагуу өнгөн хөрсний дээжлэлт гүйцэтгэсэн бөгөөд хэмжилтийн үр дүнгийн үнэмшилийг нэмэгдүүлэх зорилгоор Завхан аймгийн Ус, цаг уур орчны шинжилгээний газрын Улиастай төвийн мониторингийн цэгүүдийг хамруулсан. Лабораторийн задлан шинжилгээг МУИС-ийн Хүрээлэн буй орчны лаборатори болон Япон улсын Каназава их сургуулийн Байгаль орчны технологийн хүрээлэнгийн Геохимийн лабораторид хөрсний хүнд элементийн агууламжыг ICP-MS болон ICP-OES аргазүйгээр хэмжилт гүйцэтгэсэн. Судалгааны үр дүнгийн урьдчилсан боловсруулалтаас үзэхэд Улиастай хотын хүрээнд хүнцэлийн агууламж анхаарал татахуйц өндөр агууламтай байгаа бол хүлцэх агууламжаас кобальт, хром зэрэг элементүүд давсан утгатай байгаа бөгөөд бохирдлын гол тархалт нь голын арал орчмын бүс, цахилгаан станц, сургуулийн халаалтын уурын зуух зэрэг газрууд багтаж байна. Улиастай хот нь орчим жилийн хугацаанд баруун бүсийн засаг захиргаа, эдийн засгийн бүс болж байсан газар ашиглалтын түүхтэй бүс нутгийн хувьд хөрсний бохирдол анхаарал татах хэмжээнд хүрсэн байна. Улаанбаатар хот нь нийгэм-эдийн засгийн голлох төв ач холбогдол бүхий суурин газрын хувьд хөрсний бохирдолд хүчтэй өртөн, хар тугалга, хром, азот зэрэг элементүүд цагаан хаалга, баянбүрд, 100-н айлын худалдааны төв, Нарантуул ОУХТ зэрэг газруудад бүртгэгдсэн байна. иймд хөрсний бохирдолоос хүний эрүүл мэндэд үзүүлэх нөлөөллийн эрсдэлийн үнэлгээг USEPA-ийн аргыг ашиглан хүүхэд том хүн дээр тооцоолсон. Үр дүнд бидний Улаанбаатар хотын гэр хороололд хийгдсэн тооцоотой харьцуулахад Улиастай сумын хөрсний бохирдол хүний эрүүл мэндэд үзүүлэх эрсдлийн үнэлгээний үр дүн эрсдэл өндөр гарсан нь суурийн газрын хөрсний хүнд металлын бохирдол хот хөдөөд нүүрснээс шалтгаалан ижилхэн өндөр байгааг харуулж байна.
Abstract: There is two types of dwelling in capital city in Mongolia such as Ger and apartment. The Ger is a Mongolian traditional house. Residents of Ger districts in Ulaanbaatar, use coal as a source of fuel for their daily life activities such as heating and cooking in winter due to lack of central heating systems. Coal ash is generated into a form of powder that contains heavy metals toxic to human health deposited at the bottom the oven after coal burning. In this study, we as-sess the heavy metal exposure pathways to coal ash, which has potential adverse effects on Ger district residents’ health and quality of life, using questionnaires at specific sites where concen-trations of heavy elements were identified in our previous study. Survey results indicate that residents store the coal ash in packing bags and metal garbage cans outside and inside fences of their households for at least two weeks due to poor waste management. Due to weak seals of the packaging material and open metal cans deposited with the coal ash, the ash is easily transport-ed into the surrounding area due to wind action. Adults come into contact with contaminated soil when they are cleaning areas outside and inside the fence, and children are exposed when the play in playgrounds outside the fences. Such activities represent dermal, inhalation and in-gestion pathways of the contaminants for the adults and children. Түлхүүр үгс: өртөх замууд: залгих; амьсгалах; арьсны; нүүрсний хэрэглээ; гэр хорооллын оршин суугчид; нийгмийн судалгаа; үндсэн бүрэлдэхүүн хэсгүүдийн шинжилгээ
The aim of the present study was to evaluate human health and potential ecological risk assessment in the ger district of Ulaanbaatar city, Mongolia. To perform these risk assessments, soil samples were collected based on reference studies that investigated heavy element distribution in soil samples near the ger area in Ulaanbaatar city. In total, 42 soil samples were collected and 26 heavy metals were identified by inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) methods. The measurement results were compared with the reference data in order to validate the soil contamination level. Although there was a large difference between the measurement results of the present and reference data, the general tendency was similar. Soil contamination was assessed by pollution indexes such as geoaccumulation index and enrichment factor. Mo and As were the most enriched elements compared with the other elements. The carcinogenic and noncarcinogenic risks to children exceeded the permissible limits, and for adults, only 12 out of 42 sampling points exceeded the permissible limit of noncarcinogenic effects.
In total, 28 drinking samples were collected between May 2020 and September 2020. Total 20 heavy metals were identified by inductively coupled plasma mass spectrometry (ICP-MS) methods at SGS company. The cancer risk evaluated by the USEPA guideline based on concentration of Co, Cr, As, Cd, Al and B elements.
In total, 28 drinking samples were collected between May 2020 and September 2020. Total 20 heavy metals were identified by inductively coupled plasma mass spectrometry (ICP-MS) methods at SGS company. The cancer risk evaluated by the USEPA guideline based on concentration of Co, Cr, As, Cd, Al and B elements.
The aim of the present study was to evaluate human health and potential ecological risk assessment in the ger district of Ulaanbaatar city, Mongolia. To perform these risk assessments, soil samples were collected based on reference studies that investigated heavy element distribution in soil samples near the ger area in Ulaanbaatar city. In total, 42 soil samples were collected and 26 heavy metals were identified by inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) methods. The measurement results were compared with the reference data in order to validate the soil contamination level. Although there was a large difference between the measurement results of the present and reference data, the general tendency was similar. Soil contamination was assessed by pollution indexes such as geoaccumulation index and enrichment factor. Mo and As were the most enriched elements compared with the other elements. The carcinogenic and noncarcinogenic risks to children exceeded the permissible limits, and for adults, only 12 out of 42 sampling points exceeded the permissible limit of noncarcinogenic effects. According to the results of the ecological risk assessment, Zn and Pb showed from moderate to considerable contamination indexes and high toxicity values for ecological risk of a single element. The Cr and As ranged as very high ecological risk than that of the other measured heavy metals. View Full-Text Keywords: health risk assessment; ecological risk assessment; ger district; heavy metals; soil pollution
The capital city in Mongolia comprises two types of dwellings: apartments and Gers. The Ger is a traditional Mongolian house. Residents of Ger districts in Ulaanbaatar use coal as a source of fuel for daily activities such as heating and cooking in winter due to lack of central heating systems. After coal burning, the ash deposited at the bottom of the oven converts into a powder containing heavy metals that are toxic to human health. Through questionnaires at sites where concentrations of heavy elements were identified in our previous study, we examined the heavy metal exposure pathways of coal ash, which has potentially adverse effects on the health and quality of life of Ger district residents. Survey results indicate that residents have to store the coal ash in packing bags and metal garbage cans near their household fences for at least two weeks because of poor waste management. Owing to the weak seals of the packaging material and open metal cans that contain the coal ash, it is easily transported into surrounding areas by the wind. Adults come into contact with contaminated soil when they are cleaning areas outside and inside the fences, and children are exposed when they play outside the fences. Such activities enhance the dermal exposure as well as inhalation and ingestion pathways of the contaminants for adults and children. View Full-Text Keywords: exposure pathways; ingestion; inhalation; dermal; coal usage; Ger residents; questionnaire survey; principle component analyses
