bioaugmented phytoremediation of cadmium and crude oil co-contaminated soil by in association with PGPR WN01
Heavy metals and petroleum oil are the two most important contaminants in the environment. Currently, phytoremediation is regarded as an effective and affordable solution that allows the attenuation of toxic pollutants through the use of plants. Not many studies are carried out regarding the use of aromatic plants capable of remediating soil that is co-contaminated by heavy metal and petroleum hydrocarbons. A pot experiment was conducted to investigate the influence of cadmium-resistant PGPR on the phytoremediation efficiency of in Cd and petroleum co-contaminated soil. The plants were harvested after 60 days of treatment and their growth and biomass were determined. The accumulation of Cd in plant shoots and roots was determined. The residual petroleum hydrocarbon concentration during the 60 days of the phytoremediation experiment was determined using GC-FID. with showed the highest Cd accumulation (14.05 mg kg) and the highest reduction of TPH (46.64%). ameliorated contaminant toxicity and promoted biomass production of . These results demonstrated that in combination with can be efficiently used to remediate Cd and petroleum-co-contaminated soils.
Responses of glyoxalase system, ascorbate-glutathione cycle, and antioxidant enzymes in to lead stress and its capacity to remove lead
A hydroponic experiment was conducted to investigate the variations in membrane permeabilities, chlorophyll contents, antioxidase activities, the ascorbic acid (AsA)-glutathione (GSH) cycle, and the glyoxalase system in the leaves of with 0 ∼ 15.0 mg L lead ion (Pb) exposure. The concentrations of Pb accumulated in the plant roots, stems, and leaves were also evaluated. After 7 days of exposure, the plants maintained normal growth, and there was a significant increase in ascorbate peroxidase and dehydroascorbate reductase activities. With 5.0 mg L Pb exposure for 28 days, nearly 66.36% of Pb accumulated in the roots, while excess Pb immobilized in the leaves was not observed. Exposure to 10.0 and 15.0 mg L Pb for 28 days significantly increased Pb contents in the leaves. This led to decrease in chlorophyll , and carotenoid contents, and to increase in the methylglyoxal content in the leaves. With 10 and 15 mg L Pb exposure, NPT and PCs contents in leaves increased. however, the glyoxalase system did not function well in the plant tolerant to Pb at higher concentrations. The AsA-GSH cycle did not cooperate with the glyoxalase system in the plant defense against Pb exposure in the present investigation.
Hyperaccumulation of metal in the apoplast contributes to the tolerance of the phytoremediator L. to manganese-contaminated water
Phytoremediation of manganese (Mn)-contaminated water requires the selection of Mn-tolerant species. This study reports on physiological changes and Mn bioaccumulation in the aquatic macrophyte cultivated under various MnCl concentrations: control, 80, 340, 600, 1000, 2000, and 4000 µM. Few visual symptoms of Mn toxicity, such as chlorosis, were observed after 10 days, especially in plants treated with 2000 and 4000 µM MnCl. High Mn accumulation was recorded, with maximum values of 23,700 and 24,600 µg g DW in the shoots and roots, respectively, at 4000 µM Mn, contrasting with 825.01 and 1587.53 µg g DW in control plants. Cellular fractioning showed that Mn in shoots and roots was mainly associated with the cell wall, with approximately 90% of the Mn in roots detected in the apoplast. There were no significant changes in net CO assimilation or respiratory rates after 5 and 10 days of Mn exposure. These results demonstrate that is a Mn hyperaccumulator species with excellent phytoremediation potential, as shown by its high bioaccumulation capacity and its ability to maintain photosynthetic efficiency under Mn stress.
Strategy on rapid selection of woody species for phytoremediation in soils contaminated with copper, lead and zinc in Shanghai
The use of woody species for the remediation of heavy metal-contaminated soils is an environmentally friendly and economically viable strategy. This study investigates the phytoextraction abilities of 15 woody species for copper, lead and zinc in contaminated soil. The results indicated that all species showed phytoextraction ability, with metal concentrations varying from 5.59 to 27.45 mg·kg for Cu, 2.79 to 16.75 mg·kg for Pb and 22.13 to 185.72 mg·kg for Zn in the stem tissues depending on the species. , and were identified as the top performers in terms of overall phytoextraction capacity. Notably, their capacity to transport zinc exceeded that of copper and lead. The enrichment of copper, lead and zinc in the soil showed a synergistic effect in the presence of heavy metal. The distribution of heavy metals within plant tissues was affected by water content and the inherent toxicity of metals. The study highlights that the accumulation of tree biomass and water content in the stem play a significant role in determining the amount of heavy metals phytoextracted. This insight offers a quick method for the rapid selection of woody species for phytoremediation in urban soils contaminated with heavy metals.
Exploring the growth and phytoremediation efficacy of in agricultural soil contaminated by shrimp aquaculture
Plants face numerous environmental challenges from biotic and abiotic stressors, with soil salinization emerging as a significant global concern. The coastal regions of Tamil Nadu, face severe environmental challenges due to discharge of saline water from shrimp farms exacerbates this issue, compromising the viability of paddy and other crops in the vicinity. This study explores the phytoremediation potential of in addressing soil salinity resulting from shrimp farming activities under field conditions over a 120-day period to restore soil health in salt affected soil. This research demonstrates exceptional salt tolerance and bioaccumulation potential in facilitating soil restoration. Significant enhancements were observed in various growth parameters, including 466% increase in plant height, 338% in fresh weight and 387% in dry weight. Biochemical parameters also showed substantial enhancements with total chlorophyll, protein, proline, phenol, and glycinebetaine levels increasing by 655%, 588%, 690%, 153%, and 531%, respectively. Enzymatic activities exhibited notable elevations as well, with catalase, peroxidase, and polyphenol oxidase activities escalating by 258%, 587%, and 121% respectively, indicating robust adaptation to saline environments. Moreover, exhibited remarkable bioaccumulation capabilities, accumulating 461 kg NaCl ha. This led to substantial improvements in soil characteristics, including a reduction in pH from 8.8 to 6.49, electrical conductivity from 5.7 to 1.53 dSm, and sodium adsorption ratio from 16.1 to 4.4 mmol L. The successive cultivation of in this study, has proven to be a viable strategy for reclaiming salt-affected lands, thereby alleviating a significant constraint on crop productivity.
Sustainable Methylene Blue dye removal with activated carbon from Prosopis juliflora stem
This study addresses the environmental challenge posed by the invasive Prosopis juliflora plant by converting its stem into activated carbon for the adsorption of Methylene Blue dye from water. The goal is to create an effective and sustainable wastewater treatment solution. Prosopis juliflora stems were harvested, cleaned, dried, carbonized, and activated with zinc chloride to create Prosopis Juliflora Stem Activated Carbon. This activated carbon was characterized using Brunauer-Emmett-Teller surface area analysis, Fourier transform infrared spectroscopy, and scanning electron microscope imaging. Results revealed a significant surface area of 158.107 m/g and the presence of functional groups essential for adsorption processes. Batch adsorption experiments were conducted to determine the efficiency of activated carbon in removing Methylene Blue dye at various dosages and contact times. The highest adsorption efficiencies were 73.5% at 80 min, 90.1% at 60 min, and 90.65% at 50 min for dosages of 80, 100, and 120 mg, respectively. These findings show that Prosopis Juliflora Stem Activated Carbon is highly effective at removing Methylene Blue dye, providing a cost-effective and environmentally friendly method of wastewater treatment.
Shields against pollution: phytoremediation and impact of particulate matter on trees at Wigry National Park, Poland
This study examines the impact of airborne particulate matter (PM) and associated trace elements (TEs) on deciduous and coniferous trees at the edge of Wigry National Park in northeast Poland, focusing on pollution levels and the potential for phytoremediation. Researchers measured PM concentrations in the air and on the leaves of , , and , along with photosynthetic indicators (Fv/Fm ratio and performance index). The study found significant differences in pollution intensity across areas with varying levels of human activity. , an evergreen species, accumulated the highest PM levels (>200 μg/cm), while had the highest accumulation among deciduous trees (>50 μg/cm). Trace elements such as Fe, Cu, Zn, Sr, and Cd were detected, with being the most efficient in accumulating Cd (up to 7.5 mg/kg). The accumulation of pollutants correlated with reduced photosynthetic efficiency in trees closest to pollution sources. The findings suggest that strategically planting specific tree species can help mitigate air pollution in national parks and protect sensitive vegetation. Future research should explore the long-term effects of PM on forest health and the role of different species in phytoremediation.
Effective adsorption of Cr(VI) from aqueous solution by Mg-Fe LDH supported on orange peel activated carbon: isotherm, kinetic, thermodynamics and mechanism studies
The toxic Cr(VI) contaminating water released from the metallurgical, dyeing, and electroplating industries is getting worse day by day and is extremely hazardous to human health. Thus, the development of a cost-effective, quick, and efficient adsorbent is highly essential for the Cr(VI) decontamination from wastewater. Herein, a microwave-assisted carbon-based composite called Mg-Fe LDH@OPAC was prepared by assembling Mg-Fe LDH onto orange peel-activated carbon (OAPC). Prior to investigating deeply into the adsorption behavior of the composite, the Mg-Fe LDH@OPAC formation was confirmed by using instrumental techniques like FESEM, EDS, Zeta potential, XRD, FTIR, Raman, XPS, and BET analyzer. The material had a high surface area of 143.9 m/g and showed a good monolayer Langmuir uptake capacity of 118.36 mg/g. Under ideal circumstances, the maximum amount of Cr(VI) was removed within just 120 min and showed high efficiency in the presence of other coexisting anions respectively. The adsorption was accounted by pseudo-second-order kinetics and spontaneous in nature. Ultimately, a possible adsorption mechanism was suggested, confirmed by XPS studies; which showed that oxidation-reduction, electrostatic interaction, and surface complexation reaction were responsible for Cr(VI) adsorption on Mg-Fe LDH@OPAC surface.
Bioenergy products sequestration proportions among three mixotrophically cultivated microalgae by remediating two organic waste resources
In this study, three microalgae species were cultivated using dairy and fish wastewater: , and sp. The process involved manipulating various physicochemical conditions, to determine optimal growth parameters. Our evaluation considered cell count, biomass productivity, specific growth rate, pigments, carbohydrates, proteins, lipid compositions, and cellulose stored in microalgae. A significant observation of highest cellulose accumulation was recorded in cultivated in dairy waste (DW) medium (2.54 ± 0.042 µg/mg). In contrast, the species grown in fish waste (FW) media recorded a lower level (0.9405 ± 0.06 µg/mg) of cellulose. In DW, and accumulated substantial amounts of astaxanthin and carotenoid, respectively. Carbohydrate, protein, and lipid accumulation was maximized in DW culture, with exhibiting a more incredible carbohydrate content. Lipid analysis showed as sp. was capable of accumulating alpha-linolenic acid. The disparity may be attributed to DW's nutritional and mineral content, which encourages cellulose deposition. The FTIR analysis confirmed the accumulation of cellulose. These findings underscore the potential of DW and FW media as valuable resources for microalgal biofuel and ethanol production, offering a hopeful future for sustainable energy production.
Phytoremediation potential of potted plant species against vehicular emissions
Urbanization and industrialization are exponentially deteriorating air quality, ecosystems, and human health. Phytoremediation is cost cost-effective, sustainable, and nature-based solution against air pollution. This study is designed to evaluate four species, , a, , and for their phytoremediation potential. The experimental setup consisted of a sealed chamber to place potted plants and equipment, it was also connected to the vehicular exhaust pipe. The Air Pollution Tolerance Index was highest for (12.19) and lowest for (8.58) has the highest VOC removal efficiency (90%, 0.172 ppm h). NO remediation was highest by with 0.057 ppm h (77%) removal efficiency. SO and CO were remediated more efficiently by as 89%, (0.18 ppm h) and 80% (0.23 ppm h), respectively. reduced a higher concentration of NH (77%, 0.06 ppm h) compared to other species. and may serve as bio-indicator species. These findings provide a sustainable, natural, economical, and eco-friendly way to mitigate air pollution. and are suitable species for urban landscapes, green spaces, urban plantations, and green walls to curb air pollutants due to traffic and industries.
Screening of multi-metal tolerant plant growth promoting bacteria (PGPB) WA4 and its assistance on phytoextraction of heavy metals (Cu, Ag and Pb)
In the current study, coal fly ash contaminated soil was collected in and around Mettur Thermal Power Station, Salem district, Tamil Nadu. The metal concentrations present in the coal fly ash soil samples were analyzed and also used for the isolation of bacteria. The isolates were screened for their multi-metal resistance against three heavy metals (Cu, Ag and Pb) and plant growth-promoting traits (siderophore, phosphate solubilization, IAA, cellulase, HCN, and ammonia production). Among the 12 isolates, the WA4 strain revealed promising results for both metal-resistant and plant growth-promoting activity. In the pot experiment, (Palak), (Red spinach), (Green chilly) and (Brinjal) plants were grown in ash-contaminated soil treated with different concentrations of selected bacterial inoculum (25%, 50%, 75% and 100%) along with a control pot. The results of the study indicated that the ash-contaminated soil treated with bacterial inoculum distinctly increased the growth of plants when compared to untreated soil (control). Thus, the best-performing strain WA4 could be utilized as a good bio-stimulant for promoting the growth of selected plants in the re-vegetation programs of ash-contaminated soil.
Eco-friendly banana peel biochar for adsorption of toxic metals from landfill treatment pond leachate
Adsorption is one of the most efficient ways to eliminate hazardous metals. The study evaluated the effectiveness of banana peel biochar as a cheap adsorbent to remove hazardous metals from landfill leachate. The landfill leachate of 100 mg/L was mixed with banana peel biochar (0.50, 1.50, and 3.00 g each) and placed in a water bath for 15, 30, and 45 min at a constant temperature of 30 °C and 35 °C. The adsorption efficiency of banana peel biochar for nickel in the leachate ranged from 98.76% to 98.96% and chromium ranged from 99.71% to 99.77% at a temperature of 30 °C for 15 mins and 99.07% to 99.27% for Ni and 99.71% to 99.73% for Cr at a temperature of 35 °C for 45 min. Banana peel biochar maximum adsorption capacity of nickel ranged from 1.15 × 10 mg/g to 5.27 × 10 mg/g, and 1.05 × 10 mg/g to 6.76 × 10 mg/g for chromium. Adsorbent made from less expensive banana peel can affordably remove nickel and chromium from landfill leachate. To acquire a broad understanding of the adsorbent's application, more adsorptive research utilizing banana peels as an adsorbent to treat various wastes ought to be conducted.
Menadiol diacetate mediated subcellular Cd accumulation and nutrients uptake alleviates Cd toxicity and increases growth and yield of summer squash
Cadmium (Cd) has shown toxicity to reduce growth and productivity in different plants. The Present study investigated the efficacy of menadiol diacetate (MD) to reduce Cd stress on growth and yield of summer squash plants. The experiment was performed under saturated Hoagland's nutrient solution (control) while the other group was supplemented with 0.1 mM CdCl (Cd stress). Surface sterilized seeds of summer squash were primed in different concentrations (10, 20 µM) of MD as well as in distilled water for 24 h and sown in the pots. Different morphological and physio-biochemical attributes were determined after 35 d of growth whereas the data for yield attributes was collected after 70 d. Cd concentration was determined in various subcellular compartments cell walls and cell wall debris, chloroplast, cell membrane and other organelles including vacuoles. The Cd stress decreased photosynthetic pigments, osmoprotectants and ultimately caused reduction in the yield attributes. Further, it increased the secondary metabolites and oxidants (MDA and HO) in the summer squash tissues. Cd exposure also altered ions accumulation in the summer squash tissues by increasing the root and shoot Ca (24-93%) and Fe (4-18%) ions while decreasing the Mg (31-39%) ions. The MD-priming, particularly at 10 µM concentration mediated increase in the total phenolics, ascorbic acid, and anthocyanins concentration, and thus enhanced growth and yield attributes of summer squash exposed to Cd toxicity. Further, 10 µM MD-priming facilitated Cd compartmentalization in the subcellular compartments mainly in the cell wall (58%) rather than in the chloroplast (18%), cell membrane (7%) and soluble fractions (18%). In this context, cell wall and vacuole were the key compartments for Cd sequestration. This study highlights MD-priming as a potential strategy to counter Cd toxicity in summer squash plants.
Metal phyto-accumulation potential, biochemical response, and health risk assessment of selected wheat varieties grown in municipal sewage sludge amended soils
Present study identified metal accumulation potential, biochemical, growth, and human health risk attributes of wheat varieties (Zincol-16, NARC-09, NARC-11, Pakistan-13, Borlaug-16) cultivated in sewage sludge amended soils, that is, 80% soil + 20% sludge (C), 90% soil + 10% sludge (B) and 100% soil (control, A). Metal accumulation significantly varied ( < 0.05) among wheat varieties and the accretion pattern was roots > straw > grains. The Borlaug-16 was found most efficient for biochemical attributes, that is, proline (0.84), sugar (2.76) and total chlorophyll (2.35) in mg/g amongst selected varieties. Among treatments, maximum mean total chlorophyll (2.18), carotenoids (0.97), sugar (2.88) in mg/g, plant height (76.04 cm), weight per 1000 kernel (55 g) and spike length (4.17 cm) were recorded in B followed by A > C. However, mean membrane stability index%, that is, A (82.76)>B (75.26)>C (54.35) and mean proline contents, that is, C (0.49)>B (0.39)>A (0.29) in mg/g were recorded respectively. Mean hazard quotient and hazard index (HI) calculated on the basis of grain metal contents followed the trend, that is, C > B > A. The HI results revealed highest and lowest health risks associated with the consumption of Zincol-16 and Borlaug-16, respectively. The 'Borlaug-16' and 'sludge treatment B' are recommended for cultivation and as rate of application, respectively, for ensuring food safety and agro-ecological health.
Elicitors fortifies the plant resilience against metal and metalloid stress
This review addresses plant interactions with HMs, emphasizing defence mechanisms and the role of chelating agents, antioxidants and various elicitor molecules in mitigating metal toxicity in plants. To combat soil contamination with HMs, chelate assisted phytoextraction using application of natural or synthetic aminopolycarboxylic acids is an effective strategy. Plants also employ diverse signaling pathways, including hormones, calcium, reactive oxygen species, nitric oxide, and Mitogen-Activated Protein Kinases influencing gene expression and defence mechanisms to counter HM stress. Phytohormones enhance the enzymatic and non-enzymatic antioxidant defence mechanism and the level of secondary metabolites in plants when exposed to HM stress. Also it activates genes responsible for DNA repair mechanism. In addition, the plant hormones can also regulate the activity of several transporters of HMs, thereby preventing their entry into the cell. Elicitor molecules regulate metal and metalloid absorption, sequestration and transport in plants. Combining of different elicitors like jasmonic acid, calcium, salicylic acid etc. effectively mitigates metal and metalloid stress in plants. Moreover, microbes including bacteria and fungi, offer eco-friendly and efficient solution for HM remediation. Understanding these elicitors, microbes and various signaling pathways is crucial for developing strategies to enhance plant resilience to metal and metalloid stress.
Antioxidant and pH-dependent cationic and anionic dye degradation activities of optimum synthesized organic@inorganic Cu hybrid nanoflowers
First time in this study, hybrid Cu nanoflowers (Cu hNFs) were synthesized with algae extract and the pH-dependent catalytic activities of hNFs synthesized under optimum conditions against brilliant blue and methylene blue dyes were determined. Ideal morphology of hNFs, were synthesized by using 1 ml extract in PBS (pH 7.4). The diameter and petal thickness of optimum synthesized hNF were 7-22 µm, and 35.5 nm, respectively. Main skeleton component (C, O, P, and Cu) of hNFs were determined by EDX. The presence of functional groups and primary phosphate crystals formed by Cu and phosphate reaction in the PBS buffer were confirmed by FT-IR analysis. The hNFs exhibited the antioxidant activity (IC = 1.27 mg/ml, = 0.6971) against to DPPH (2,2-diphenyl-1- (2,4,6-trinitrophenyl) hydrazyl). hNFs degraded methylene blue and brilliant blue dyes at the highest at pH 9 (73.85%) and pH 5 (68.19%) media, respectively. Catalytic activities of hNFs against methylene blue and brilliant blue dyes were explained by Fenton mechanism. The findings are thought to be used in new type hNF synthesis and various environmental applications.
Biosorption potential of (Malabar spinach) for removal of fluoride in aqueous solutions based on its phytoremediation applications; a review
This review article explores the applications of Basella alba (Malabar spinach), a fast-growing vine plant known for its numerous health benefits, culinary uses, and potential in dye and oil production. Fluoride contamination in water poses a significant global health and environmental challenge, particularly in regions where natural and industrial activities lead to elevated fluoride levels. Among its varied applications, has shown significant promise in the phytoremediation of contaminants in both water and soil, owing to its hyper accumulating capacities. The plant has a transfer factor value of more than 1 which means that there is higher accumulation of contaminants in parts of the plant than in soil. The objective of this review is to assess the feasibility of B. alba in contributing to sustainable water management solutions for fluoride contamination, while offering a comprehensive evaluation of its environmental remediation potential. The article examines the biosorption capabilities of B. alba based on its established use in phytoremediation, offering insights into its suitability for addressing fluoride contamination in water. This article is organized into sections starting with an introduction, which brings explains the global challenge of fluoride, and different treatment techniques justifying why biosorption needs to be considered, cases of application of phytoremediation using B. Alba, and finally exploring the success factors for plants that have been applied for both biosorption and phytoremediation.
In-situ biosynthesis of metallic nanoparticles using and extract: characterization and application in dye decolorization
The synthesis of catalysts has gained specific concern due to their versatile applications in particular azo dye decolorization. In the current work, metallic nanoparticles (copper and silver) were In-situ biosynthesised using and extract. The obtained -copper oxide and -silver oxide materials were analyzed using SEM, TEM, FT-IR, TGA-DTG, SEM, TEM, and XRD techniques. peels had a rough surface, with nanoparticles equally distributed over it. The crystal structure of peels was altered after the addition of CuO and AgO nanoparticles. The highest residual mass values in the prepared materials indicated that the metallic nanoparticles were, , formed. The prepared materials had worse thermal stability than peel powders. The azo dyes, Calmagite and Naphthol Blue Black B were tested in the catalytic power of the resulting materials. The decolorization process was affected by the dye structure, amount of HO, dye concentration, time of reaction, and temperature of the bath. The activation energy values for -CuO were 18.44 kJ mol for calmagite, and 23.28 kJ mol for naphthol blue black, respectively. Nevertheless, the energy values for -AgO were 50.01 kJ mol for calmagite and 12.44 kJ mol for Naphthol blue black. The calculated low energy values for the prepared materials suggested the high efficiency of the use of these catalysts in azo dye decolorization under the change of some main experimental conditions.
Stress reduction with co-culture of and in a pb contaminated soil to improve biomass production
The industrial past of most regions in Lorraine and the intensification of activities on soils has increased the number of polluted sites. To rehabilitate these areas, several methods can be employed. In this study, co-culture of Miscanthus x giganteus and Pelargonium x hortorum was used to clean up a soil mainly contaminated by metallic elements including lead. The use of ornamental plants has been little studied, even if these species can be used to rehabilitate a site while improving its esthetics. At the end of the experiment, Pb concentrations were measured in the soil and plants. Furthermore, phytohormones were also measured to evaluate the defense mechanisms of the plants in front of pollutants. The results showed a reduction in Pb concentrations following the phytoremediation process implemented and that PxH was able to extract Pb from the soil. Results showed that co-culture was not beneficial to the development of MxG. Concerning the molecules synthesized by the plants under stress conditions, only salicin was found in MxG roots and aerial parts in particular for plants grown in individual culture. According to the results obtained, it seems that MxG is able to make compromises between the synthesis of protective molecules and its development.
Particulate matter retention and removal efficiency in ten tree species of semi-arid environment
Modern era has witnessed particulate matter (PM) become one of the biggest threats for the existence of biological species. Therefore, a study was performed in Faisalabad city to evaluate PM retention and removal efficiency of ten local tree species. Branch samples were collected from urban, sub-urban and rural areas in September 2020 (183 days after rain), and in August 2021 (30 days after rain). Results showed that total PM load, PM and PM- retention was the highest in urban followed by sub-urban and rural area. PM, PM-, total PM, and PM deposition rate decreased significantly in the following order, during both years 2020, and 2021. During the artificial rainfall experiment, total PM removed by the species also followed the same order however, PM removal efficiency was the highest in and followed by and Therefore, it can be concluded that species selection must be done skillfully for congested urban environment.
Application of dairy wastewater as substrate for bioremediation of coal mine drainage in planted horizontal flow constructed wetland
Coal mine drainage (CMD) is an environmental threat due to its high volume, low pH, presence of toxic metals, and absence of biodegradable organics. The present study aims to treat CMD in a horizontal sub-surface flow constructed wetland (CW) using dairy wastewater as an organic source. CW was planted with Characteristics of synthetic CMD were (except pH, all unit mg/L) pH 1.9; Fe: 100, : 1,000, Mn: 6, Zn: 5, Co: 1, Ni: 1, and Cr: 1. CMD was mixed with synthetic dairy wastewater (pH: 5.05, COD: 2,700 mg/L, BOD: 1,600 mg/L) in the ratio of 3:1. Alkalinity of 120-190 mg/L CaCO was generated and effluent pH improved from 2.2 to 6.6. Metals precipitated as metal sulfide or hydroxide. Sulfate removal was hindered due to the synergistic toxicity of several metals. Except for Mn, all other effluent parameters were within the discharge limit for disposal in inland surface water.