The Effects of Water Recycling on Flotation at a North American Concentrator—Part 1

Water chemistry and its impact on mineral processing operations are not well understood and often not adequately monitored. CanmetMINING, as part of its water management research program, has been involved in a project initiated to identify opportunities for improving water recovery, water treatment, and recycling in the mining and mineral processing operations. One of the main objectives of this work is to evaluate and assess water chemistry and identify factors that impact mineral recovery, concentrate grade, and metal extraction efficiencies in order to understand and mitigate negative impacts of water recycling and improve process efficiency. In collaboration with a North American concentrator, CanmetMINING has been involved in assessing the water chemistry in the mill and evaluating water recycling options for select process streams to reduce fresh water intake and maximize recycling. The overall goal of the project is to investigate options for water recycling (increase the thickener overflow recirculation from thickener overflow tank) without affecting nickel and copper metallurgy. The results of the sampling campaigns showed that the water chemistry of the streams was fairly consistent throughout the year with no significant seasonal variations. The laboratory tests illustrated that when higher quantities of thickener overflow from thickener overflow were used, the nickel + copper grade versus nickel recovery curves shifted towards lower values. These observations were observed for the plant water samples obtained in April, June and August 2019.

Analysis of Gray Water Recycling by Reuse of Industrial Waste Water for Agricultural and Irrigation Purposes

Isfahan industrial province with its numerous industrial estates in its area and consequently the amount of wastewater produced by these settlements is very difficult to deal with.Therefore,the need for proper wastewater treatment and efficient management of industrial waste water from the industrial estates of this province should be seriously addressed and followed up by the authorities.The purpose of this study is the feasibility of reuse of wastewater from industrial settlements for agricultural and irrigation purposes.The present study is a descriptive cross-sectional study.In this study,the average values obtained from the sampling and the results of the experiments on waste water from the industrial waste water treatment plant in Isfahan,2017,have been used.Average values of BOD5,COD,TSS and so on were compared with the standards set by the Environmental Protection Agency and analyzed in Excel software.According to the results,the average values of COD,BOD5,TSS,SO4,pH and catalyst quality parameters were determined from wastewater effluents of 315,162,93,164(mg/L),8.3 and 32.5(NTU)respectively.The results of the study show that the average values of the quality parameters examined from the effluent of the treatment plant other than BOD5 and COD are within the standard range and the limit for agricultural and irrigation purposes,which may lead to undesirable environmental performance of these two parameters.

A Preliminary Study on Cactus as Flocculants in Water Recycling from Moroccan Phosphates Schlamms

In this work we used a new organic biodegradable flocculants which is the cactus cladodes juice in order to recycle water from phosphate schlamms. This flocculants has enabled us to increase the settling velocity of the schlamms so consequently the water recycled degree. The study was conducted on an industrial sample of phosphates schlamms from Khouribga phosphates washing plant. The study was about the influence of concentration, pH, and velocity gradient with cactus extract leads to satisfactory results in term of settling decantation, and in water recycling degree which is 93%.

Implications of de Facto Reuse on Future Regulatory Developments for Beaufort-Jasper Water & Sewer Authority in Okatie, South Carolina, USA

A significant portion of the national water supply can be attributed to de facto or unplanned potable reuse, though the extent of its contribution is difficult to estimate. Fortunately, the contribution of Water Resource Recovery Facility (WRRF) effluent to waters that supply drinking water treatment plants has been documented by some communities. In the United States (US), among the top 25 most impacted drinking water treatment plants by upstream WRRF, 16% of the influent flow to the drinking water treatment plant under average streamflow and up to 100% under low-flow conditions is WRRF effluent. Currently, the full extent of de facto reuse in the US may be much higher because of population growth. The scenario is no different for Beaufort-Jasper Water and Sewer Authority (BJWSA) in South Carolina, US, with contributions to the Savannah River originating from numerous WRRF and other upstream dischargers. South Carolina coastal utilities such as BJSWA are considering direct and indirect potable reuse options, driven by disposal limitations and challenges. Currently, South Carolina does not have a framework, guidelines, or regulations for reuse, but discussions have started among the regulated community. In addition to understanding the extent of de facto reuse, the state will need to develop standards and best practices to enable future adoption of planned potable reuse solutions to water resources challenges. Such guidance should address human health risk management and technical considerations regarding treatment in addition to other factors, including source control, storage, fail-safe operation, monitoring, non-cost factors, and public acceptance. This study conducted a mapping assessment specific to BJWSA, sampled at four locations on Savannah River, and observed that de facto reuse is approximately 4.6% to 5.9% during low-flow months and is within the range generally observed nationwide. When coupled with evidence that planned potable reuse can improve human health and environmental risks, this practice is a meaningful option in the water supply portfolio for many utilities.

Innovative Technologies for Large-Scale Water Production in Arid Regions: Strategies for Sustainable Development

Water scarcity in arid regions poses significant challenges to sustainable development and human well-being. This article explores both existing and innovative technologies and methods to produce large amounts of water to address these challenges effectively. Key approaches include atmospheric water generation, advanced desalination techniques, innovative water collection methods such as fog nets and dew harvesting, geothermal water extraction, and water recycling and reuse. Each method is evaluated for its feasibility with existing technology, potential time of implementation, required investments, and specific challenges. By leveraging these technologies and combining them into a multifaceted water management strategy, it is possible to enhance water security, support agricultural and industrial activities, and improve living conditions in arid regions. Collaborative efforts between governments, private sector entities, and research institutions are crucial to advancing these technologies and ensuring their sustainable implementation. The article provides a comprehensive overview of the current state of these technologies, their potential for large-scale application, and recommendations for future research and development.

Optimization of the wash process and wash water recycling in the preparation of MgZnAl-CO_3 layered double hydroxides

An MgZnAI-CO3 layered double hydroxide （LDH） slurry with Na2 S04 as the by-product has been prepared by a co-precipitation method. The filtrates in the LDH washing process were collected according to their different levels of salinity. Filtrates with lower salinity can be used to wash a LDH slurry with higher salinity in the next cycle. Only in the final stages is pure water used. Recycling of the wash water in this way has been employed in a commercial production process, resulting in a water-saving of over 80%. The resulting MgZnAI-CO3-LDH product has a well-formed crystalline layered structure with a low content of impurities.

Effect of impurities in recycling water on Pb-Ag anode passivation in zinc electrowinning process

Effect of impurities in recycling water on Pb-Ag anode passivation in zinc electrowinning process was investigated by linear scan voltammetry.Results show that passivation process would be affected in the presence of Cl^-and F-in recycling water.It was highly advantageous to take H2SO4 concentration as 180g/L,Mn^2＋ concentration as 3-5 g/L and F-less than 42mg/L.However,passivation process would not be affected when Cl^-concentration was less than 13mg/L without any other ions,or when mass ratio of Mn^2＋ to Cl^-existing in electrolyte was 8,where Cl^-concentration could reach up to 625mg/L.

In situ combined chemical and biological assessment of estrogenic pollution in a water recycling system

Estrogenic pollution and its control in aquatic systems have drawn substantial attention around the world. The chemical and biological assessment approaches currently utilized in the laboratory or field cannot give an integrated assessment of the pollution when used separately. In this study, in situ chemical and biological methods were combined to detect pollution in a water recycling system. Data for the water quality index（WQI） demonstrated that the water treatment resulted in the decline of pollution from upstream to downstream.Wild male Nile tilapia, Oreochromis niloticus, was sampled in June and September. The concentrations of four common endocrine disrupting chemicals（EDCs） were determined in the tilapia liver by chromatographic analysis methods. The level of 17β-estradiol（E2） declined from upstream to downstream in both months. In contrast, the levels of bisphenol A（BPA）,di-（2-ethylhcxyl） phthalate（DEHP）, and perfluorooctane sulfonate（PFOS） did not display this declining tendency. The highest relative expression of vitellogenin 1（VTG1） was observed in tilapia from upstream, then the level significantly decreased along the water system. The relative expression levels of CYP1A1 in the water system were also significantly higher than that of the control. However, no declining trend could be observed along the water system. The change of VTG1 expression corresponded well with that of E2 levels in the tilapia liver. Overall,our study assessed the pollution by endocrine disruptors using chemical and biological data with good correspondence. This study also demonstrated the effectiveness of the water recycling system in eliminating estrogen pollution in municipal sewage.

Influence of Wetland Self-purification Capacity on the Utilization of Water Resources——A Case Study of the Project for Recycling Yanshan River Water

[ Objective] The study aims to resolve water resource problem availably. [ Method] On the basis of wetland self-purification capacity, Yanshan River water was purified by Xixi Wetland, and the feasibility of using treated Yanshan River water for urban greening and watering road was analyzed. [Result] Compared with direct utilization of tap water, it is more economic to recycle Yanshan River water purified by Xixi Wetland for urban greening and watering read, with obvious economic, ecological and social benefits, so it is an effective method to address shortage of water resources and is worth spreading. [ Conclusion] It is feasible to use Yanshan River water purified by Xixi Wetland for urban greening and watering read.

Repeated batch fermentation with water recycling and cell separation for microbial lipid production

Large waste water disposal was the major problem in microbial lipid fermentation because of low yield of lipid. In this study, the repeated batch fermentation was investigated for reducing waste water generated in the lipid fermentation of an oleaginous yeast Trichosporon cutaneum CX1 strain. The waste fermentation broth was recycled in the next batch operation after the cells were separated using two different methods, centrifugation and flocculation. Two different sugar substrates, glucose and inulin, were applied to the proposed operation. The result showed that at least 70% of the waste water was reduced, while lipid production maintained satisfactory in the initial four cycles. Furthermore, it is suggested that T. cutaneum CX1 cells might produce certain naturally occurring inulin hydrolyzing enzyme（s） for obtaining fructose and glucose from inulin directly. Our method provided a practical option for reducing the waste water generated from microbial lipid fermentation.

Performance of recycling abrasives in rock cutting by abrasive water jet

Rock cutting performance of recycling abrasives was investigated in terms of cutting depth, kerf width, kerf taper angle and surface roughness. Gravity separation technique was employed to separate the abrasives and the rock particles. The recycling abrasive particles were then dried and sieved for determination of their disintegration behaviors. Before each cutting with recycling abrasives, the abrasive particles less than 106 ?m were screened out. It is revealed that a considerable amount of used abrasives can be effectively reused in the rock cutting. The reusabilities of abrasives are determined as 81.77%, 57.50%, 34.37% and 17.72% after the first, second, third and fourth cuttings, respectively. Additionally, it is determined that recycling must be restricted three times due to the excessive disintegration of abrasives with further recycling. Moreover, it is concluded that cutting depth, kerf width and surface roughness decreases with recycling. No clear trend is found between the kerf taper angle and recycling. Particle size distribution is determined as an important parameter for improving the cutting performance of recycling abrasives.

Synthesis and Scheduling of Optimal Batch Water-recycle Networks

This work develops an optimization-based methodology for the design and scheduling of batch water recycle networks. This task requires the identification of network configuration, fresh-water usage, recycle assignments from sources to sinks, wastewater discharge, and a scheduling scheme. A new source-tank-sink representation is developed to allow for storage and dispatch tanks. The problem is solved in stages by first eliminating scheduling constraints and determining minimum usage of fresh water and wastewater discharge. An iterative procedure is formulated to minimize the total annual cost of the system by trading off capital versus operating costs. The work overcomes limitations in previous literature work including restricted recycle within the same cycle, lumped balances that may not lead to feasible solutions, and unrealistic objective functions. A case study is solved to illustrate the usefulness of the devised procedure.

Hydrological analysis of Kuroshio water intrusion into the South China Sea

Using CFD and ADCP data collected by four research vessels from both sides of the Taiwan Strait in the northeastern area of the forth China Sea in August - September 1994 and incorporating with CTD data collected in the same area in March 1992 and some historical hydrologic data, the water features and the intrusion of Kuroshio water into the South China Sea are discussed, which shows that the water mass distribution in the survey period was similar to that in the cruise of late winter and early spring (March 1992), that is, the water structure in the northeast of the sea and in the Northwest Pacific had their own independent features of temperature and salinity. Though the intrusion of Kuroshio water into the sea was found, it was very weak. Therefore there would be no direct Kuroshio branch into the sea in the late summer and early autumn. Even the Kuroshio water intrusion from the Bashi Channel into the Taiwan Strait, its influence was also very weak. Analysis of isopycnic surface and geretrophic current and the Observed ADCP data show that there was a rather strong northward flow in the southeast pat of the survey area which flowed northward along the west coast of Philippines, rounded the northwest corner of Luzon Island and then flowed northeastward. Some kind of mixing with Kuroshio water was shown in the Bashi Channel. The water mass was obviously of high temperature and low salinity in winter and comparatively low temperature and low salinity in summer.

Impact of Untreated Sedimentation Tank Sludge Water Recycle on Water Quality During Treatment of Low Turbidity Water

The overall purpose of this research is to examine the impact of untreated sedimentation tank sludge water( USTSW) recycle on water quality during treatment of low turbidity water in coagulation—sedimentation processes. 950 m L of raw water and different concentrations of 50 m L USTSW are injected into six 1 000 m L beakers without coagulant.The results indicate that USTSW characterized as accumulated suspended solids and organic matter has active ingredients,which possess the equivalent function of coagulant. The optimal blended water turbidity is in the range of 10-20 NTU,within which USTSW recycle achieves the highest save coagulant rate. The mechanism of strengthening coagulation effect when USTSW recycle mainly depends on the chemical effect and physical effect. What is more,through scanning electron microscopy( SEM),it is found that the floc structures with USTSW recycle are more compact than those without USTSW recycle. Besides,the water quality parameters of color,NH3-N,CODMn,UV254,total aluminum,total manganese when USTSW recycle is better than the raw water without recycle,indicating that USTSW recycle can improve water quality with strengthening coagulation effect.

Sustainable wastewater treatment and reuse in space

Exploring the vast extraterrestrial space is an inevitable trend with continuous human development.Water treatment and reuse are crucial in the limited and closed space that is available in spaceships or long-term use space bases that will be established in the foreseeable future.Dedicated water treatment technologies have experienced iterative development for more than 60 years since the first manned spaceflight was successfully launched.Herein,we briefly review the related wastewater characteristics and the history of water treatment in space stations,and we focus on future challenges and perspectives,aiming at providing insights for optimizing wastewater treatment technologies and closing the water cycle in future.

Flocculation of the Moroccan phosphates slimes

In Morocco, the phosphate industry generates by washing during the ore beneficiation in humid way, big quantities of sludge loaded in fine mineral particles （or slimes） with contents of water in the order of 90-95%. The specific consumption in water for the beneficiation of one tone of dry ore is approximately 0.6 m3. The management of this sludge and the recycling of process water are played to a schema of solid-liquid separation by flocculation, settling then stocking in basins of several dozens hectares. Recovered clear waters are recycled into the circuit of washing. The principal motivation of this work which is a part of EL MAA project is dedicated to the study of the impact of the speed of agitation on the flocculation behavior in terms of dewatering of the phosphate slimes and recycling of the process water. Study was driven on sample of slimes taken in entrance of the thickeners of a Moroccan washing plants, before flocculation. The raw slimes have a concentration in solid of 75.5 g·L^-1, a P205 grade of 17.3% and a free settling velocity 9 cm·h^-1. Fine fraction -2 μm, responsible for the poor settling of slimes is composed in practice of nearly 96% of smectite. It represents 9% of the dry solid content in the slimes. Measurements reveal important variations of the granulometric and textural properties of large floes in response to flocculation, opening ways of optimization for the velocity gradient.

Biochar and zero-valent iron sand filtration simultaneously removes contaminants of emerging concern and Escherichia coli from wastewater effluent

Advanced treated municipal wastewater is an important alternative water source for agricultural irrigation.However,the possible persistence of chemical and microbiological contaminants in these waters raise potential safety concerns with regard to reusing treated wastewater for food crop irrigation.Two low-cost and environmentally-friendly filter media,biochar(BC)and zero-valent iron(ZVI),have attracted great interest in terms of treating reused water.Here,we evaluated the efficacy of BC-,nanosilver-amended biochar-(Ag-BC)and ZVI-sand filters,in reducing contaminants of emerging concern(CECs),Escherichia coli(E.coli)and total bacterial diversity from wastewater effluent.Six experiments were conducted with control quartz sand and sand columns containing BC,Ag-BC,ZVI,BC with ZVI,or Ag-BC with ZVI.After filtration,Ag-BC,ZVI,BC with ZVI and Ag-BC with ZVI demonstrated more than 90%(>1 log)removal of E.coli from wastewater samples,while BC,Ag-BC,BC with ZVI and Ag-BC with ZVI also demonstrated efficient removal of tested CECs.Lower bacterial diversity was also observed after filtration;however,differences were marginally significant.In addition,significantly(p<0.05)higher bacterial diversity was observed in wastewater samples collected during warmer versus colder months.Leaching of silver ions occurred from Ag-BC columns;however,this was prevented through the addition of ZVI.In conclusion,our data suggest that the BC with ZVI and Ag-BC with ZVI sand filters,which demonstrated more than 99%removal of both CECs and E.coli without silver ion release,may be effective,low-cost options for decentralized treatment of reused wastewater.

Seasonal dynamics of cyanobacteria and eukaryotic phytoplankton in a multiplereservoir recycling irrigation system

Background:Agricultural runoff recycling systems are manmade aquatic ecosystems of growing significance to global water sustainability,crop health,and production.This study investigated the seasonal dynamics of microbial community in a three-reservoir recycling irrigation system with a stepwise water flow and compared with that of an adjacent runoff-free stream.Runoff water from all production areas was captured in a sedimentation reservoir which overflowed to a transition reservoir then retention reservoir through a culvert.Stream water was pumped to replenish the reservoirs as needed during growing seasons.Results:16S rDNA PCR clone libraries of quarterly water samples from three reservoirs and one stream were sequenced,and 575 operational taxonomic units(OTUs)were identified and assigned to cyanobacteria,eukaryotic phytoplankton,and other bacteria.When compared to the stream,three reservoirs consistently had low microbial diversity.A distinct seasonal pattern of microbial community structure was observed for each reservoir and the stream.Stream was consistently dominated by other bacteria.Retention reservoir was dominated by cyanobacteria during the summer and fall and eukaryotic phytoplankton during the winter and spring.Sedimentation reservoir was dominated by cyanobacteria beginning in the spring but that dominance was altered when water was pumped from the stream from early spring to fall seasons.Transition reservoir had the greatest shift of microbial community structure,being dominated by other bacteria in the summer,cyanobacteria in the fall,and eukaryotic phytoplankton in the winter and spring.Water temperature and ammonium level were the two most important contributing factors to the seasonality of microbial community in these reservoirs.Conclusions:The three recycling irrigation reservoirs consistently had lower microbial diversity and distinct community structure when compared to the stream.These reservoirs were typically dominated by cyanobacteria during warm seasons and eukaryotic phytoplankton during cool seasons.This seasonal pattern was altered when water was pumped from the stream.The cyanobacteria dominance was associated with rising water temperature and ammonium level.These results highlight the importance of preventing agricultural runoff from entering natural waterways and water resources and provide a useful framework for further investigations into the ecological processes of this emerging ecosystem.

Treatment of spent wash water derived from shredded lettuce processing using a combination of electrocoagulation and germicidal ultraviolet light

Objective:Water recycling is a significant part of an overall water management system.The current study evaluated electrocoagulation,used in combination with ultraviolet light(at 254 nm),to reduce the organic content and enhance the microbiological quality,of wash water derived from shredded lettuce processing.Method:The composition of spent wash water derived from a commercial lettuce processing operation was used to prepare a simulated solution to be applied to validate the water recycling system.The simulated spent wash water was subjected to an electrocoagulation process followed by filtration and a tertiary ultraviolet(254 nm)treatment.The efficacy of the recycling treatment to decrease turbidity(nephelometric turbidity units,biological oxygen demand(BOD),chemical oxygen demand(COD)and decrease in introduced bacterial numbers.Results:Spent wash water sampled from a commercial processing line was found to be colloidal in nature(78±26 NTU)with low total solids content(544±87 mg/L),BOD(230±53 mg/L)and COD(309±53 mg/L).An electrocogaultion process performed for 10 min using 3.48 A/m2 current density at pH 6.5 and conductivity of>100μS/cm supported an 87%removal of turbidity,38%reduction in BOD along with 49%decrease in COD.The electrocoagulation process was also found to reduce the levels of Escherichia coli,Salmonella and Listeria monocytogenes by 1-2 log cfu.The tertiary UV treatment of water derived from the electro coagulation process,supported further reduction in model pathogens,although it was noted that the D values for inactivation were in the order of 1.01-1.60 mJ/cm^(2),which compares to 0.22-0.31 mJ/cm^(2) in saline.The apparent increase in bacterial resistance to ultraviolet was likely due to the UV absorbing low molecular weight constituents within wash water that provided protection against inactivation.Conclusion:In conclusion,the study demonstrated the feasibility of applying electrocoagulation and UV to rapidly treat spent lettuce wash water to facilitate in-process recycling within shredded lettuce processing operations.

Fifty Years of Water Sensitive Urban Design, Salisbury, South Australia

Australia has developed extensive policies and guidelines for the management of its water. The City of Salisbury, located within metropolitan Adelaide, South Australia, developed rapidly through urbanisation from the 1970s. Water sensitive urban design principles were adopted to maximise the use of the increased rim-off generated by urbanisation and ameliorate flood risk. Managed aquifer recharge was introduced for storing remediated low-salinity stormwater by aquifer storage and recovery （ASR） in a brackish aquiter for subsequent lrngatlon. Ibis paper outlines now a municipal government has progressively adopted principles of Water Sensitive Urban Design during its development within a framework of evolving national water policies. Salisbury＇s success with stormwater harvesting led to the formation of a pioneering w aterbusiness that includes linking projects from nine sites to provide a non-potable supply of 5 ×10^6 m^3 year. These installations hosted a number of applied research projects addressing well configuration, water quality, reliability and economics and facilitated the evaluation of its system as a potential potable water source. The evaluation showed that while untreated stonnwater contained contaminants, subsurface storage and end-use controls were sufficient to make recovered water sale for public open space irrigation, and with chlorination acceptable lbr third pipe supplies. Drinking water quality could be achieved by adding microfiltration, disinfection with UV and chlorination. The costs that would need to be expended to achieve drinking water safety standards were found to be considerably less than the cost of establishing dual pipe distribution systems. The full cost of supply was determined to be AUD$1.57 m ＂ for non-potable water for pubhc open space lrngatlon much cheaper than mares water, AUD $3.45 m at that time. Producing and storing potable water was found to cost AUDS1.96 to $2.24 m .