The soils situated near the abandoned mines are highly polluted with metals due to the discharge and dispersion of mine waste into nearby air, water (surface and groundwater) and soil. Heavy metals may be transferred to humans through ingestion, inhalation or dermal absorption and can produce serious health problems affect the nervous, endocrine and immune systems, hematopoietic function and cellular metabolism. This paper investigates the presence of metallic elements from fourteen soil samples (seven sampling points) and thirty-six vegetation samples (different types of leaves, plants, roots and tree barks). The samples were collected from six different sites located in an abandoned mining area and from a point (blank sample) located 5 km in the SV direction of the quarry. The results obtained for soil samples show an overrun of the alert and / or intervention threshold for the following metals: arsenic, cadmium, cobalt, copper, manganese, nickel, lead and zinc. The analytical investigation for vegetation samples indicated that concentration for calcium, magnesium, cadmium, chromium, manganese, nickel, lead, zinc were situated over the normal range in some samples. The analytical investigations were performed by optical emission spectrometry (ICP-OES). The study�s conclusion indicates that, as result of soil acidic pH and high mobility of some metals, metallic elements migrate from soil to vegetation.
(1) Background: A comparative research study to remove Congo Red (CR) and Methyl Orange (MO) from single and binary solutions by adsorption onto cobalt ferrite (CoFe2O4) and cobalt ferrite–chitosan composite (CoFe2O4-Chit) prepared by a simple coprecipitation method has been performed. (2) Methods: Structural, textural, morphology, and magnetic properties of the obtained magnetic materials were examined by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, N2 adsorption–desorption analysis, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and magnetic measurements. The optimal operating conditions of the CR and MO removal processes were established in batch experiments. The mathematical models used to describe the processes at equilibrium were Freundlich and Langmuir adsorption isotherms. (3) Results: Cobalt ferrite–chitosan composite has a lower specific surface area (SBET) and consequently a lower adsorption capacity than cobalt ferrite. CoFe2O4 and CoFe2O4–Chit particles exhibited a superparamagnetic behavior which enabled their efficient magnetic separation after the adsorption process. The research indicates that CR and MO adsorption onto prepared magnetic materials takes place as monolayer onto a homogeneous surface. According to Langmuir isotherm model that best fits the experimental data, the maximum CR/MO adsorption capacity is 162.68/94.46 mg/g for CoFe2O4 and 15.60/66.18 mg/g for CoFe2O4–Chit in single solutions. The results of the kinetics study revealed that in single-component solutions, both pseudo-first-order and pseudo-second-order kinetics models represent well the adsorption process of CR/MO on both magnetic adsorbents. In binary solutions, adsorption of CR/MO on CoFe2O4 better follows the pseudo-second-order kinetics model, while the kinetic of CR/MO adsorption on CoFe2O4–Chit is similar to that of the dyes in single-component solutions. Acetone and ethanol were successfully used as desorbing agents. (4) Conclusions: Our study revealed that CoFe2O4 and CoFe2O4–Chit particles are good candidates for dye-contaminated wastewater remediation.
The focus of this study was to assess the treatment performance and granule progression over time within a continuous flow reactor. A continuous flow airlift reactor was seeded with aerobic granules from a laboratory scale sequencing batch reactor (SBR) and fed with dairy wastewater. Stereomicroscopic investigations showed that the granules maintained their integrity during the experimental period. Laser diffraction investigation showed proof of new granules formation with 100-500 μm diameter after only 2 weeks of operation. The treatment performances were satisfactory and more or less similar to the ones obtained from the SBR. Thus, removal efficiencies of 81-93% and 85-94% were observed for chemical oxygen demand and biological oxygen demand, respectively. The N-NH(+)(4) was nitrified with removal efficiencies of 83-99% while the nitrate produced was simultaneously denitrified - highest nitrate concentration determined in the effluent was 4.2 mg/L. The removal efficiency of total nitrogen was between 52 and 80% depending on influent nitrogen load (39.3-76.2 mg/L). Phosphate removal efficiencies ranged between 65 and above 99% depending on the influent phosphate concentration, which varied between 11.2 and 28.3 mg/L.
The growth of population has been linked with the increase usage of chemical compounds design for domestic and industrial use. At its turn, the increased amount of the chemical compound puts an enhanced stress on the environment. In such scenario, the waste management, including the wastewater treatment strategies have become an important part for the environmental protection. Unfortunately, the wastewater treatment procedures have several components which could be improved. Among them aeration process and biomass sedimentation have been the most stringent to tackle, since the aeration alone consume more than 60% from wastewater treatment energy cost. In this study, we proposed a new microalgae-bacteria activated sludge granule which could be an economical and technological solution to the above mentioned issues such as aeration and sedimentation. Moreover, during this study we characterized the physical, morphological and chemical characteristic of the newly formed granules by advances techniques such as electronic and correlative microscopy.
This paper emphasized the influence of the main operating parameters of ultrasonic biological sludge pretreatment onto disintegration (DD-COD) and solubilizing degree of organic matter content. The optimal ultrasonic reaction time, energy and amplitude of ultrasonic waves and pH of the sludge (non-modified pH and pH 8.5) were established taking into account their influence on the solubility level of COD, an evolution of particles size. Correlations between disintegration degree and dimensional analysis were performed. Ultrasonic reactor operating to 20 kHz ultrasound frequency was a close system having cooling water jacket. Experimental tests in different operating conditions (reaction time 5 � 60 min., ultrasound energy 2000 � 9000 kJ, pH = 6.5/8.5) demonstrated that alkaline ultrasonic treatment (pH = 8.5, initial homogeneous COD = 72600 mg O2/L) at medium - high ultrasound energy levels led to highest disintegration degree � DD 12% (comparing with pH = 6.5 � DD ~ 5%). Still, the process should be managed carefully because of possibility to have important variation of DD during the ultrasonic treatment.
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