Оценка эффективности очистки модельных растворов шахтных вод карбонатными реагентами

ABSTRACTAs the desire for chemical warfare (CW) capability has developed among the nations of the world, the need for equipment, as well as personnel, to survive in a chemically contaminated environment increases. Navy facilities, vessels and operations are possible targets for CW attack. Chemical contamination and decontamination can cause significant damage to Navy equipment and material.Requirements for DOD components to address nuclear, biological and chemical (NBC) contamination Survivability —consisting of decontaminability, hardness to both agents and decontaminants, and compatibility of equipment with personnel dressed in full NBC protective ensemble — have been established by DOD Instruction 4245.13. Design and material considerations addressing CW contamination Survivability should be planned early in the development and acquisition cycles of new equipment/systems for the Navy.

Resource-efficient purification of acidic multi-metal process water by means of anionic nanofibrillated cellulose

A study was conducted to evaluate the efficacy of recycled concrete aggregate (RCA) and off-specification fly ash (FA) in remediating acid mine drainage (AMD). The pH and AMD concentrations of calcium (Ca), magnesium (Mg), iron (Fe), chromium (Cr), copper (Cu), manganese (Mn) and zinc (Zn) were assessed. The effects of RCA particle size on pH and AMD metal concentrations were also investigated. Results showed that RCAs were effective in neutralising the acidic pH and lowering the AMD concentrations of iron, chromium, copper and zinc. The concentrations of calcium increased, but magnesium and manganese concentrations varied in the treatment process. FA acted as an additional source of metals and increased the concentrations of iron, copper and manganese significantly. Finer RCA particles were the most effective in raising the pH and reducing the AMD concentrations of magnesium, manganese and zinc. The concentrations of calcium, iron, chromium and copper remained unaffected by the RCA particle size. In addition, geochemical modelling indicated that sorption was the leaching controlling mechanism in untreated and FA-treated AMD, whereas it was solubility-controlled leaching in RCA-treated AMD. Finally, the research reported in this study suggests the use of RCA as an effective alternative to the conventional treatment methods for AMD remediation.

Assessing the sustainability of acid mine drainage (AMD) treatment in South Africa

The toxicity to Penicillium digitatum and practical use of carbonate and bicarbonate salts to control green mold were determined. The effective dose (ED50) concentrations to inhibit the germination of P. digitatum spores of sodium carbonate (SC), potassium carbonate, sodium bicarbonate (SBC), ammonium bicarbonate, and potassium bicarbonate were 5.0, 6.2, 14.1, 16.4, and 33.4 mM, respectively. All were fungistatic because spores removed from the solutions germinated in potato dextrose broth. SC and SBC were equal and superior to the other salts for control of green mold on lemons and oranges inoculated 24 h before treatment. When sodium content and high pH must be minimized, SBC could replace SC. Furthermore, because a higher proportion of NaOCl would be present in the active hypochlorous acid at the lower pH of SBC compared to SC, sanitation of the SBC solution should be easier to maintain. NaOCl (200 μg/ml) added to SBC at pH 7.5 improved green mold control. Rinse water as high as 50 ml per fruit applied after SC did not reduce its effectiveness; however, high-pressure water cleaning after SC did. Conversely, high-pressure water cleaning of fruit before SC improved control of green mold. The risk of injury to fruit posed by SC treatment was determined by immersing oranges for 1 min in 3% (wt/vol) SC at 28, 33, 44, 50, 56, or 61°C (±1°C) and followed by storage for 3 weeks at 10°C. Rind injuries occurred only after treatment at 56 and 61°C. The risk of injury is low because these temperatures exceed that needed for control of green mold. SC was compatible with subsequent imazalil and biological control treatments.

Acid mine drainage is wastewater from a mine having a low pH and an elevated level of dissolved heavy metals. These metals are harmful to aquatic, animal and human life. This paper looks at the removal of copper from acid mine drainage using ion exchange to less than 1 mg/l. A weak acidic cation resin was used. Spectrophotometric determination of copper with sodium diethyldithiocarbamate was used to determine the copper concentrations in the treated water. Using regression analysis, the experimental results gave a correlation coefficient of 0.977 and a coefficient of determination of 99.5%. Results indicated that the higher the flows rate the shorter the period after which the copper concentration in the treated water reaches 1 mg/l. At pH 3.85 and 5.09, the resin performed better and at pH above 6.62 and between pH 3.0 and below the resin’s does not perform well. The higher the resin height the greater is the resin exchange capacity and the longer it takes for the copper concentration to reach 1 mg/l in the treated water. The higher the wastewater copper concentration the shorter the time it takes the resin to reach 1 mg/l. The results for this experiment indicated that acid mine drainage can be treated well by ion exchange resins, but it is also very important to establish suitable operating conditions.

Integrated treatment of acid mine drainage using BOF slag, lime/soda ash and reverse osmosis (RO): Implication for the production of drinking water

Unconfined compressive strength (UCS) of high plasticity clayey soil mixed with 5 and 10 % of Portland cement and four chemical agents such as sodium hexametaphosphate, aluminum sulfate, sodium carbonate, and sodium silicate with 0, 5, 10, and 20% concentrations was comparatively evaluated. The individual and combined effects of the cement and chemical agents on the UCS of the soil mixture were investigated. The strength of the soil-cement mixture generally increases with increasing the cement content. However, if the chemical agent is added to the mixture, the strength of the cement-chemical agent-soil mixture tends to vary depending on the type and the amount of the chemical agent. At low concentrations of 5% of aluminum sulfate and 5% and 10% of sodium carbonate, the average UCS of the cement-chemical agent-soil mixture slightly increased compared to pure clay due to increasing the flocculation of the clay in the mixture. However, at high concentrations (20%) of all chemical agents, the UCS significantly decreased compared to the pure clay and clay-cement mixtures. In the case of high cement content, the rate of UCS reduction is the highest among all cement-chemical agent-soil mixtures, which is more than three times higher in comparison to the soil-chemical agent mixtures without cement. Therefore, in the mixture with high cement (> 10%), the reduction of the USC is very sensitive when the chemical agent is added.

The scientific-practical problem of the regulation of chemical parameters of water quality, namely concentrations of sodium, calcium, magnesium, potassium at the outlet of filters, which in turn is an integral part of the scheme of the process of purification of drinking water, is considered. An algorithm for the formation of an optimal structure of the ion exchange filter module and the structure of the control system that implements this algorithm is proposed. The analysis of filters for water purification showed that they are mainly intended to reduce rigidity, turbidity, purification of iron, sulfates, chlorides, nitrates and organic impurities. The proposed work is devoted to increasing the efficiency of water purification from such elements as magnesium, calcium, tri-potassium and potassium, or more precisely, to normalize these indicators to the values defined by the state standard, which involves the introduction of appropriate ion-exchange filters. The aim of this article is to develop a control system algorithm, which increases the efficiency of the stage of fine water purification by forming the optimal structure of the module of ion exchange filters and determining the appropriate flow of purified water. It has been determined that the ion exchange filter is a periodic apparatus and, in order to ensure the continuity of the purification process, the filter module must contain backup capacities in the form of additional filters of different purposes, which creates the preconditions for optimizing the structure of the specified filter module. On the basis of the analysis of the current state of the equipment for purification of drinking water, an algorithm for determining the optimal structure of the module for ion exchange filters and the corresponding flow of purified water is investigated. Implementation of the control system based on the given algorithm will increase the efficiency of the stage of fine purification of the installation of water treatment.

Contaminated mine water with a large amount of salts makes underground and surface water sources unsuitable for household and drinking needs. Already in 2016, there was a shortage of drinking water in the Rostov region. Water from surface sources does not meet the hygienic requirements for chemical parameters in 36.1% of the samples taken. Water from underground sources in terms of color, turbidity, total hardness, dry residue, content of iron ions, manganese, hydrogen sulfide, nitrates, ammonia, chlorides, sulfates, magnesium, sodium did not meet the required standards in 72.2% of cases. Due to the need for huge expenses for the purification of highly mineralized waters and the poor development of cheap technologies for the neutralization of large volumes, attempts to purify discharged or flowing mine waters to a safe level turn out to be practically fruitless. In this article, studies were carried out to reduce the concentration of dissolved ions of heavy metals (iron, manganese, copper and zinc) in mine wastewater by sorption in a static mode (charring) using rice husk biochar with electromagnetic treatment. The authors proposed a method for pre-treatment of the sorbent from rice husk biochar in an electromagnetic field at a process activation unit. The results of laboratory tests confirmed the high efficiency of the sorbent for the removal of heavy metal ions from mine waters. On the basis of the results obtained, optimization of the sorption purification of mine waters in the mode of carbonization was carried out using the method of mathematical planning of the experiment (full factorial experiment FFE 2k). The factors most influencing the efficiency of mine wastewater treatment from iron and zinc ions have been identified. With a probability of 0.95, the proposed models are adequate, and they can be used to describe the sorption process when using the studied sorbent to remove heavy metal ions (iron, zinc, etc.), while the optimal concentration of the sorbent from rice husks is within 0.5 mg/l. With an increase and decrease in the concentration of the sorbent above the optimal values, the efficiency of sorption decreases, and this affects the iron to a greater extent. In general, the obtained sorbent has a chemical composition similar to that of activated carbon (the most widely used sorbent for water purification), but at the same time it is a cheap production waste, which confirms its efficiency, both technological and economic, when used to purify natural and waste water. With the introduction of the proposed treatment scheme for mine water treatment facilities, it is expected that the concentrations of dissolved heavy metal ions, in particular, iron, zinc, manganese, will decrease to the concentration of the discharge into the reservoir.

Treatment of mining-influenced water at Malanjkhand copper mine

Valorization of acid mine drainage (AMD): A simplified approach to reclaim drinking water and synthesize valuable minerals – Pilot study

Six groups, each of six sheep, were fed in pens for 15 months on a ration of chaffed lucerne and wheaten hays. One group was offered rain-water to drink, another group was offered 1.30% sodium chloride, whereas the others were offered one of the following mixtures of sodium chloride, carbonate, and bicarbonate: 1.26 + 0.015 + 0.025, 1.21 + 0.04 + 0.06, 1.12 + 0.08 + 0.13, and 0.95 + 0.161+ 0.25%. The intake of all saline solutions was higher than that of rain-water, ranging from 150% above for 1.30% sodium chloride to 60% above for the highest level of carbonates; the mean daily intakes for the entire experiment by the six groups were 2.6, 6.6, 4.8, 5.7, 5.8, and 4.2 l. respectively. The intake also increased in all groups with temperature, being 40–70% higher in the hottest months than in the coldest months.Weight increase was less from 6 months onward in the group receiving 1.30% sodium chloride, and was less at certain times only in the experiment in the groups receiving 0.04 or 0.10% carbonates, than in that receiving rain-water (control group). There were no differences in weight increase between the control group and the groups receiving the highest concentrations (0.21 and 0.41%) of carbonates The saline drinking waters had no effect on the concentrations of sodium, potassium, calcium, magnesium, or chloride in the blood plasma. The concentration of carbon dioxide was higher, for the last year of the experiment, in the blood of the control group, and, for approximately one-third of the experiment, in that of the group receiving the highest level of carbonates in its drinking water, than in that of any of the groups receiving lower levels of carbonates. There were differences in blood carbon dioxide on one occasion only between the control group and that receiving the highest level of carbonates. None of the solutions used in the experiment had any adverse effect on the general health, food consumption or wool production of the sheep.

Comparison of mine water neutralisation efficiencies of different alkaline generating agents

Recovery of drinking water and valuable minerals from acid mine drainage using an integration of magnesite, lime, soda ash, CO2 and reverse osmosis treatment processes