Dissolved organic matter and arsenic removal with coupled chitosan/UF operation

Characteristics of Soil Arsenic Contamination and the Potential of Pioneer Plants for Arsenic Remediation in Gold Mine Tailings

Arsenic (As) contamination of gold mine tailings poses major threats to the natural environment and human health, necessitating adequate management measures. To investigate the soil As contamination level and the potential of pioneer plants for As remediation, the soil and plants of an abandoned gold mine tailings in the Qinling Mountains were analyzed. The level of As contamination was assessed using the single-factor pollution index and potential ecological risk index, and its bioeffectiveness was analyzed. The enrichment capability of plants was investigated using the bioaccumulation factor and translocation factor. Redundancy analysis and partial least squares regression were employed to investigate factors affecting the distribution of As in soil and plants. The results show that As in soil mainly existed in the difficult-available state, with serious contamination and extremely high ecological risk. Lythrum salicaria L. and Equisetum ramosissimum Desf. are the preferred plants for remediation of As contamination through screening pioneer plants. Soil total nitrogen (STN) and available phosphorus (SAP) are the main factors influencing the characteristics of As distribution in the soil. Soil available potassium (SAK), water content (SWC), and SAP promote the accumulation of As by plants. This study provides plant materials and new ideas for mine ecological remediation.

Arsenic removal methods for drinking water in the developing countries: technological developments and research needs

Arsenic pollution of drinking water is a concern, particularly in the developing countries. Removal of arsenic from drinking water is strongly recommended. Despite the availability of efficient technologies for arsenic removal, the small and rural communities in the developing countries are not capable of employing most of these technologies due to their high cost and technical complexity. There is a need for the "low-cost" and "easy to use" technologies to protect the humans in the arsenic affected developing countries. In this study, arsenic removal technologies were summarized and the low-cost technologies were reviewed. The advantages and disadvantages of these technologies were identified and their scopes of applications and improvements were investigated. The costs were compared in context to the capacity of the low-income populations in the developing countries. Finally, future research directions were proposed to protect the low-income populations in the developing countries.

Removal of As(III) and As(V) from water by chitosan and chitosan derivatives: a review

As arsenic removal becomes a global concern, the development of removal processes for arsenic treatment is still a major challenge. With regard to environmental compatibility and cheapness, chitosan and chitosan derivatives are considered as a promising removal technology for arsenic. Chitosan and chitosan derivatives possess the properties of low cost and good sorption on the arsenic removal. The present review is concerned about the present understanding of the mechanisms involved in sorption processes. Further on, detailed discussions are given of the effects of various factors on the performance of chitosan and chitosan derivatives in arsenic treatment processes. Finally, special attention is paid to the future challenges of chitosan and chitosan derivatives utilized for industrial arsenic treatment.

Novel Water Treatment Processes Based on Hybrid Membrane-Ozonation Systems: A Novel Ceramic Membrane Contactor for Bubbleless Ozonation of Emerging Micropollutants

The aim of this study is the presentation of novel water treatment systems based on ozonation combined with ceramic membranes for the treatment of refractory organic compounds found in natural water sources such as groundwater. This includes, firstly, a short review of possible membrane based hybrid processes for water treatment from various sources. Several practical and theoretical aspects for the application of hybrid membrane-ozonation systems are discussed, along with theoretical background regarding the transformation of target organic pollutants by ozone. Next, a novel ceramic membrane contactor, bringing into contact the gas phase (ozone) and water phase without the creation of bubbles (bubbleless ozonation), is presented. Experimental data showing the membrane contactor efficiency for oxidation of atrazine, endosulfan, and methyl tert-butyl ether (MTBE) are shown and discussed. Almost complete endosulfan degradation was achieved with the use of the ceramic contactor, whereas atrazine degradation higher than 50% could not be achieved even after 60 min of reaction time. Single ozonation of water containing MTBE could not result in a significant MTBE degradation. MTBE mineralization by O3/H2O2combination increased at higher pH values and O3/H2O2molar ratio of 0.2 reaching a maximum of around 65%.

Use of chitosan and chitosan-derivatives to remove arsenic from aqueous solutions--a mini review

Arsenic removal has become a relevant concern due to the final confirmation of its behaviour as chronic human carcinogen, corresponding to an ever-increasing contamination of water, soil and crops in many parts of the world. Developing easily accessible removal strategies is therefore a primary environmental matter. Chitosan and chitosan derivatives show good adsorption performances against arsenic removal and are considered low cost products, easily obtainable. This review provides a summary of recent advances of the application of these compounds in the area of sorption sciences for arsenate and arsenite removal from water, focusing on equilibrium and kinetic mechanisms.

As(III) removal by hybrid reactive membrane process combined with ozonation

The removal of arsenite (As(III)) was investigated using a combined ozonation-reactive ceramic membrane incorporated with iron oxide nanoparticles (IONs). A disk-type γ-Al(2)O(3) ultrafiltration membrane (CM) was covered with IONs using an annealing method. The reactive ceramic membrane (RM) was then characterized using SEM, zeta potential measurements, and pure water permeability tests. The results showed that IONs were well attached on the RM surface. In addition, doped IONs had no significant effects on the pure water permeability and the isoelectric point (IEP) of RM. Laboratory-scale experiments were subsequently conducted to investigate the impact of combined RM and ozonation processes on As(III) rejection. The experimental results revealed that As(III) rejection rate of RM with an ozonation process (92%) significantly enhanced compared with that of CM (63%). The influence of operating parameters (i.e., pH, NOM, co-existing ions and temperature) revealed that an increase of pH, a decrease of temperature and presence of NOM led to a higher As(III) rejection, whereas the presence of co-existing ions in the feed water significantly reduced the As(III) rejection; divalent counter-ions were the greatest inhibitors for As(III) rejection. Finally, a comparison of As(III) rejection in synthetic water and real groundwater confirmed the importance of real conditions in the hybrid reactive membrane process with continuous ozonation.