Ecological treatment of El Kriymat boiler ash for recovering vanadium,nickel and zinc from sulfate leach liquor

The primary goal of this work is to develop a technology that allows for the recovery of metal values from waste products, thereby promoting the wise and efficient use of our nation's resources. To achieve this goal, an industrial waste of El Kriymat boiler fly Ash was used for recovering its content of vanadium, nickel and zinc. About 97, 95 and 99% respectively of these economic elements were first dissolved from boiler fly ash magnetic concentrate (after physical concentration). Leaching experiments using optimum conditions include: 180 g/L sulfuric acid concentration and 4% solid/solid proportion manganese dioxide acts as an oxidant at 80 °C. The recovery of vanadium (V) metal ions was carried out using 3% Alamine 336 in kerosene at an equilibrium pH value of 0.9. Subsequently, 15% sodium sulfide solution was used for co-precipitation of nickel and zinc metal ions in the raffinate solution at pH value of 3.5.

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Production of artificial aggregates by granulation and carbonation of recycled concrete fines

There is a growing need to find ways to reuse fine concrete waste from the construction industry. In this study, recycled concrete fines were granulated and used as lightweight aggregates. Ladle slag, a steel industry residue, was used as a co-binder in different ratios (0, 10, 20, and 30%). The materials were blended and granulated, and then the granules were cured in three conditions: ambient condition, humidity chamber, and carbonation chamber. The results showed that the ladle slag content of 30% cured in a humidity chamber produced the strongest granules, with a crushing strength of 127 N, which was 135% greater than a commercial lightweight aggregate. The granules generally had satisfactory density and water absorption with a higher ladle slag content. Carbonation increased the granule strength with a low ladle slag content and decreased the granules’ water absorption. The improved physical and mechanical properties of carbonated granules are attributed to the formation of calcium carbonate during the carbonation process. The granules produced in this study show good potential for use as lightweight aggregates in the construction industry.

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Estimating uncertainties in the life cycle assessment of composting household biowaste and urban green waste in Germany

Life cycle assessment (LCA) of waste treatment processes is often associated with considerable uncertainties. The aim of this study is to estimate the total uncertainty in the modelled composting system and the influence of material and process parameters on the uncertainty. Four composting combinations with fresh (FC) and mature substrate compost (MSC) from partially enclosed (PEC) and open composting (OC) were investigated. Perturbation analysis was used to determine the effect of parameters on the result and Monte Carlo simulation was used to estimate the total uncertainty. This study showed that the production of MSC using PEC had the lowest overall impacts across all impact categories except ozone depletion. Results of the Monte Carlo simulation showed that comparing composting options was challenging. The sensitivity ratios obtained from the perturbation analysis showed that the process parameter percentage of carbon fraction degraded was the most influential for FC. In MSC, the moisture content in the input material and the substitution factor used for peat were the most influential. Monte Carlo simulations demonstrated the overall uncertainty of the model and its relevance when comparing results between combinations. The perturbation analysis identified the parameters that required more accurate data to reduce the uncertainty in the model.

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Utilization of alum sludge waste for production of eco-friendly blended cement

This work was focused on evaluating the suitability of replacing Portland cement (PC) by 5, 10 and 15 mass % of activated alum sludge waste (AAS) as a pozzolanic material. Exploitation of low-cost nanocomposite for bolstering the physical, mechanical, and stability against firing of PC–AAS-hardened composites was inspected. CuFe₂O₄ spinel nanoparticle with average particle size (~ 50 nm) was prepared. Inclusion of CuFe₂O₄ spinel in different PC–AAS-hardened composites bolsters their physicomechanical features at almost normal curing ages as well as their stability against firing. The positive impact of synthesized CuFe₂O₄ spinel was affirmed via TGA/DTG and XRD techniques, which indicated the presence of diverse hydration yields such as CSHs, CASHs, CFSH, and CuSH that enhance the overall physicomechanical characteristics and thermal stability of various PC–AAS-hardened composites. The composite containing (90 PC–10 AAS waste–2 CuFe₂O₄) offers many benefits from the economic and environmental view.

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An Overview on Starch-Based Sustainable Hydrogels: Potential Applications and Aspects

Hydrogels are a kind of three dimensional polymeric network system which has a significant amount of water imbibing capacity despite being soluble in it. Because of the potential applications of hydrogels in different fields such as biomedical, pharmaceutical, personal care products, biosensors, and cosmetics, it has become a very popular area of research in recent decades. Hydrogels, prepared from synthetic polymers and petrochemicals are not ecofriendly. For preparing biodegradable hydrogels, most available plant polysaccharides like starch are utilized. In its structure, starch has a large number of hydroxyl groups that aid in hydrogel networking. For their easy availability and applications, starch-based hydrogels (SHs) have gained huge attention. Moreover, SHs are non-toxic, biocompatible, and cheap. For these reasons, SHs can be an alternative to synthetic hydrogels. The main focus of this review is to provide a comprehensive summary of the structure and characteristics of starch, preparation, and characterization of SHs. This review also addresses several potential multidimensional applications of SHs and shows some future aspects in accordance.

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Novel Pretreatment Performance Evaluation for Cellulose Nanofibrils Extraction from Ficus natalensis Barkcloth

Recently, nanosized cellulose materials extraction is extensively interesting from the sources of sustainable materials. Cellulose nanofibrils (CNF) extraction through green bio-based materials featured as promising interest in the field of science. In this study, dimethyl sulfoxide (DMSO) was applied to examine its effectiveness in pretreating the Ficus natalensis barkcloth cellulose (FNBC) for CNF production before 2,2,6,6,-tetramethylpiperidine-1-oxyl (TEMPO) oxidation. The pretreatment performance of DMSO was evaluated based on the structural and morphological changes. DMSO pretreated FNBC attained the most dramatic morphological changes as compared to untreated cellulose samples. The results of the scanning electron microscope (SEM) and transmission electron microscope (TEM) shows that there is an extensive structural disruption of FNBC during the pretreatment process, which could be because of outstanding ability to eliminate non-cellulosic materials and amorphous regions from the FNBC, confirmed by the X-ray diffractometry (XRD) showing higher crystallinity values, as well as higher thermal stabilities values of pretreated FNBC samples, were also noted. Overall, this study revealed a tremendously effective and pioneer pretreatment method for fractionating FNBC, to stimulate the successive extraction of cellulose nanofibrils. Furthermore, based on the cellulose and CNF characterizations, this study showed that F. natalensis barkcloth could be considered as an alternative source of cellulose for potential value-added industrial applications such as the food industry, paper making, and biomedicines.

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Mercury flows in a zinc smelting facility in South Korea

To prepare for the international mercury convention, the characteristics of mercury emissions from a zinc smelting facility in South Korea have been reviewed and a material flow analysis (MFA) has been conducted in this research. As inputs into the mercury MFA study, zinc ores and sulfuric acid were examined, whereas wastewater sludge, effluence water, spent catalyst, and emissions from the casting and roasting processes were examined as outputs. Mercury concentrations extracted from end products like zinc ingots, cadmium ingots, and sulfuric acid were then analyzed. Our results showed that the wastewater sludge discharged from the zinc smelting process had a relatively higher concentration of mercury, indicating that the concentration of mercury was further enriched in the wastewater sludge. The wastes discharged through the zinc smelting process should be thoroughly controlled, as results of the MFA showed that approximately 89 % of the mercury contained in the original input was later found in the waste. According to this study, the higher the concentration of mercury within zinc ores at the input stage, the higher is the mercury concentration found in the wastewater sludge at the output stage.     

Development of nutrient cycle through agricultural activities of a rural area in the North of Vietnam

Material flow analysis (MFA) has been applied to assess the environmental impact of human activities on nutrient flows at the commune scale. This paper reports the assessment of human excreta and animal manure as a nutrient source for paddy fields and fishponds in Hoang Tay commune, Ha Nam province, Vietnam. The quality of MFA model was confirmed through modified uncertainty analysis, then was used to originally quantify and visualize the interlinks of livestock with the environmental sanitation and agricultural system in terms of nutrients. Currently, half of the pig manure was collected to the biogas, and the remainders were freely discharged to the commune’s drainage system (25%) or directly reused in the paddy fields (25%). While wastewater in the drainage system was the biggest source of nitrogen (contributed 46%), paddy field was the biggest source of phosphorous (contributed 55%) discharged to the Nhue River, totaling 57 ± 9 ton N and 29 ± 6 ton P, annually. Consequently, mitigation measures for nutrient resource management were proposed, and reducing half of chemical fertilizers applied and reusing all excreta and manure in the paddy fields were the most effective option.     

Exploration of urban deposits: long-term prospects for resource and waste management.

Many materials currently in use are potentially available to become raw materials for future production if the materials are recycled instead of discarded as solid waste. However, the structure and life-expectancy of these secondary resources have not been sufficiently examined, and comprehensive methods for forecasting the availability of such materials are still lacking. This study presents a method for identifying anthropogenic material stocks in combination with the method of material flow analysis (MFA). The method was applied to copper in Switzerland as an example, with the focus on use in buildings. The exploration concept was a three-step process. First, a MFA identified the relevant stocks within the inventory of the region. Second, these stocks were inventoried through a building stock model and determination of key parameters that were defined by surveying selected buildings and from the literature. Third, the study team developed a dynamic MFA model to describe the copper stocks and flows during the period 1900-2000. The results of the copper stock calculation (in kg capita(-1)) were: buildings 79 +/- 11, infrastructure 107 +/- 25, movables 34 +/- 9, landfills 50 +/- 12. The calibrated model enabled the study team to develop resource and waste management scenarios forecasting waste flows. It is shown that the conversion of buildings into other uses may affect the waste flows significantly.     

Nutrient Dynamics in Jiaozhou Bay

Three cruises were carried out in Jiaozhou Bay (JZB) in the neap tide in October 2002 (fall) and in both neap and spring tides in May 2003 (spring) to understand the relative importance of external nutrient inputs versus physical transport and internal biogeochemical processes. Nutrients (, , , , silicic acid, total dissolved nitrogen (TDN) and phosphorus (TDP), dissolved organic nitrogen (DON) and phosphorus (DOP)) were measured. The concentrations of nutrients were higher in the northern part than in the southern part. High concentrations of and DON in JZB demonstrated the anthropogenic input. Ambient nutrient ratios indicated that the potential limiting nutrients for phytoplankton growth were silicon, and then phosphorus. Nutrients showed an obvious tidal effect with low values at flood tide and high values at ebb tide. Nutrient elements were transported into JZB in the north and output in the south (i.e., into the Yellow Sea), which varied with season, tidal cycle and investigation sites. Water exchange between JZB and the Yellow Sea exports , and DON out of JZB, while it inputs , silicic acid and DOP into JZB. Nutrient budgets demonstrate that riverine input and wastewater discharge are major sources of nutrients, while residual flow is of minor importance in JZB ecosystem. JZB is a sink for the nutrient elements we studied except for DON. Stoichiometric calculations demonstrate that JZB is a net autotrophic system.     

大型磷铵工程磷石膏制硫酸联产水泥装置的三废治理及利用

介绍了大型磷铵工程磷石膏制硫酸联产水泥装置排出的废水，废气和废渣的利用及治理情况，并对生产过程的磷、硫和氟的转化及损失量进行了衡算。     

Estimation of nitrogen flow change in Beijing,China, for the years 1995, 2000, and 2004

Rapid economic growth in China has led to environmental pollution. Recycling nutrients is essential for sustainable agriculture, and it is necessary to estimate the amount of available organic resources in order to achieve this. Using nitrogen as a tracer, we estimated the organic resource flows in 1995, 2000, and 2004 in Beijing. The agricultural nitrogen flow was calculated from the fertilizer, agricultural product, and byproduct flows. The livestock nitrogen flow was calculated from the feed, excretion, and stock flows. The human nitrogen flow was calculated from the food intake, excretion, and food waste flows. The amounts of recyclable organic resources were estimated from these nitrogen flows. The Daxing, Fangshan, Miyun, Shunyi, and Tongzho areas had high nitrogen loads in 2004, as did the outer suburbs, but Beijing proper had an extremely low nitrogen flow and the inner suburbs had low nitrogen flows. The estimated amount of compost that could be produced from domestic organic waste across Beijing was equivalent to 88,100 t of nitrogen. The Beijing area contains 394,100 ha of farmland, so, if the compost was applied at an equivalent of 100 kg of nitrogen per hectare, the equivalent of 48,000 t of nitrogen would be surplus.     

Wastewater remediation using coal ash

 Small-scale domestic septic tanks discharge excess nutrients such as phosphorus and nitrogen, as well as pathogens, which can degrade local water supplies. Unfortunately, traditional chemical and physical treatments are not practicable for single-home dwellings. This work reports on a potentially attractive solution to protect local water supplies by using a low-cost industrial waste, coal ash, for contaminant removal. Coal ash is produced as a consequence of electric power generation. The majority of the ash is disposed of in landfills and surface impoundments, or stored on- or off-site, producing large hills or leveling valleys. Only a small portion of the ash is ever utilized, mainly by cement industries and road construction. For example, in Canada less than 25% is used. Therefore, if useful applications can be found, an opportunity exists to make better use of this waste material. Bench-scale laboratory experiments and full-scale field tests show that coal ash has the capacity to remove phosphorus from domestic waste water. The experimental and field data demonstrate that phosphate levels and calcium levels can be correlated, although not in a simple manner. In addition, the ash in packed beds removed total suspended solid (TSS), biological oxygen demand (BOD), ammonia nitrogen (NH₃—N), total Kjeldahl nitrogen (TKN), and E. coli. The removal of E. coli was close 100% in the cases studied. Received: May 20, 2002 / Accepted: October 5, 2002     

Comparison of five organic wastes regarding their behaviour during composting: Part 2, nitrogen dynamic

This paper aimed to compare household waste, separated pig solids, food waste, pig slaughterhouse sludge and green algae regarding processes ruling nitrogen dynamic during composting. For each waste, three composting simulations were performed in parallel in three similar reactors (300 L), each one under a constant aeration rate. The aeration flows applied were comprised between 100 and 1100 L/h. The initial waste and the compost were characterized through the measurements of their contents in dry matter, total carbon, Kjeldahl and total ammoniacal nitrogen, nitrite and nitrate. Kjeldahl and total ammoniacal nitrogen and nitrite and nitrate were measured in leachates and in condensates too. Ammonia and nitrous oxide emissions were monitored in continue. The cumulated emissions in ammonia and in nitrous oxide were given for each waste and at each aeration rate. The paper focused on process of ammonification and on transformations and transfer of total ammoniacal nitrogen. The parameters of nitrous oxide emissions were not investigated. The removal rate of total Kjeldahl nitrogen was shown being closely tied to the ammonification rate. Ammonification was modelled thanks to the calculation of the ratio of biodegradable carbon to organic nitrogen content of the biodegradable fraction. The wastes were shown to differ significantly regarding their ammonification ability. Nitrogen balances were calculated by subtracting nitrogen losses from nitrogen removed from material. Defaults in nitrogen balances were assumed to correspond to conversion of nitrate even nitrite into molecular nitrogen and then to the previous conversion by nitrification of total ammoniacal nitrogen. The pool of total ammoniacal nitrogen, i.e. total ammoniacal nitrogen initially contained in waste plus total ammoniacal nitrogen released by ammonification, was calculated for each experiment. Then, this pool was used as the referring amount in the calculation of the rates of accumulation, stripping and nitrification of total ammoniacal nitrogen. Separated pig solids were characterised by a high ability to accumulate total ammoniacal nitrogen. Whatever the waste, the striping rate depended mostly on the aeration rate and on the pool concentration in biofilm. The nitrification rate was observed as all the higher as the concentration in total ammoniacal nitrogen in the initial waste was low. Thus, household waste and green algae exhibited the highest nitrification rates. This result could mean that in case of low concentrations in total ammoniacal nitrogen, a nitrifying biomass was already developed and that this biomass consumed it. In contrast, in case of high concentrations, this could traduce some difficulties for nitrifying microorganisms to develop.     

How to engineer biological processes that neutralize hazardous wastes

Because bioremediation must satisfy the fundamental biological tastes of specific organisms, environmental engineers must create a nutritious waste stew. Waste-hungry organisms need a proper electron acceptor. Oxygen is preferred; if it is not available, nitrate, sulfate, or carbon dioxide may work. The waste itself is a source of carbon and energy. Macronutrients are next—including phosphorus, nitrogen, and certain metals, if they are not already present in the wastewater—as well as micronutrients. Other factors, including pH, temperature, aeration, and mixing must suit the organisms' natural temperaments. This article explores how bioengineers can combine these ingredients in precise quantities and proportions in both conventional and innovative aerobic and anaerobic bioprocesses, including in situ treatment and even composting, to make the organisms healthy, happy, and inexpensive.     

Estimating construction and demolition debris generation using a materials flow analysis approach

The magnitude and composition of a region’s construction and demolition (C&D) debris should be understood when developing rules, policies and strategies for managing this segment of the solid waste stream. In the US, several national estimates have been conducted using a weight-per-construction-area approximation; national estimates using alternative procedures such as those used for other segments of the solid waste stream have not been reported for C&D debris. This paper presents an evaluation of a materials flow analysis (MFA) approach for estimating C&D debris generation and composition for a large region (the US). The consumption of construction materials in the US and typical waste factors used for construction materials purchasing were used to estimate the mass of solid waste generated as a result of construction activities. Debris from demolition activities was predicted from various historical construction materials consumption data and estimates of average service lives of the materials. The MFA approach estimated that approximately 610–780 × 10⁶ Mg of C&D debris was generated in 2002. This predicted mass exceeds previous estimates using other C&D debris predictive methodologies and reflects the large waste stream that exists.     

改性沸石复合材料的制备及对废水同步脱氮除磷

采用十六烷基三甲基溴化铵(HDTMA)溶液和LaCl3溶液对人造沸石进行改性,以实现其对废水的同步脱氮除磷。通过正交试验确定了改性沸石制备的最佳条件,并运用SEM、BET、EDS、FTIR、XRD和TG技术对改性沸石进行了表征。实验结果表明:改性可提高人造沸石对废水中氨氮(NH4+-N)和总磷(TP)的去除率;改性沸石制备的最佳条件为HDTMA质量浓度12 g/L、LaCl3质量浓度9 g/L、HDTMA溶液和LaCl3溶液的体积比1∶5,固液比1∶90;采用该条件下制备的改性沸石吸附处理NH4+-N和TP的质量浓度分别为23.78 mg/L和11.78 mg/L的废水,NH4+-N和TP的去除率分别达96.88%和95.12%。表征结果显示,改性后,HDTMA和LaCl3有效负载于人造沸石表面,且未改变人造沸石的基本骨架。     

气升式环流生物反应器处理废水厌氧过程研究

采用气升式环流生物反应器处理模拟废水。周期性通入空气和氮气来实现厌氧一好氧交替过程。对厌氧一好氧过程和普通好氧过程进行了对比,研究了厌氧处理时间和曝气速率对生物除磷效果的影响。结果表明,厌氧过程可以显著地增强生物除磷效果,与普通好氧过程相比,在进水总磷质量浓度为10mg／L时,磷的去除率可以提高30％,而COD的去除基本不受影响;适当延长厌氧处理时间和适当增大厌氧过程曝气速率可以改善厌氧环境及活性污泥性能,提高磷的去除率。     

利用啤酒废水培养极大螺旋藻

利用啤酒废水培养极大螺旋藻（Spirulina maxima）。研究了初始COD、DO、氮磷元素等培养条件对藻生物量（每mL培养液中极大螺旋藻的质量,以干重计）及废水水质的影响。实验结果表明：将废水稀释至COD=700 mg/L,控制DO=2.5 mg/L,并添加氮磷元素使废水的碳氮磷质量比为225∶15∶1,培养3 d,极大螺旋藻的藻生物量可达175.55 mg/L,即每吨啤酒废水可生产极大螺旋藻175.55 g;废水中COD,TN,NH₃-N,NO₃^-,TP的去除率分别达到85.43%,94.54%,74.66%,94.53%,61.54%。利用啤酒废水培养螺旋藻在收获极大螺旋藻生物质的同时,还能对废水起到一定程度的净化作用。