Column Experiments on Arsenic Removal Through Adsorption From Water Using Different Natural and Synthetic Adsorbents

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Modern practices for wastewater reuse in urban agriculture

Reuse of wastewater is getting progressively popular; however, it comes with a set of risks and challenges. The fit-for-purpose wastewater treatment and effective on-site farm management practices can be employed to enhance benefits and reduce risks. This paper analyses and evaluates various non-conventional treatment options and on-site farm practices for wastewater fed irrigation to grow safer products. The treatment techniques accessed covers from simple sedimentation ponds to sandbags, fabric-based and bio-sand filtrations, natural and synthetic adsorbents, and microfiltration. The advantages, risks, applicability, and limitations for all considered treatment systems have been evaluated and discussed. Likewise, farm management practices including various irrigation methods have also been evaluated. Wastewater fed drip irrigation are regarded as much safer practice, especially for the production of leafy vegetables.

Column Experiments on Arsenic Removal Through Adsorption From Water Using Different Natural and Synthetic Adsorbents

With the aim of exploring a best adsorbent from locally available sands for removing arsenic from water, eight different adsorbents are tested through column experiments using those materials as filter bed. Based on earlier batch experimental results five locally available sands (Scoria, Skye, Iron ore, NT red and TGS), one commercial sand (GFH) and two synthetic sands (IOCS and IOCS-AOCS) were selected for the column experiments. Target was to treat arsenic from water up to WHO standard level of 10 µg/L for a considerable period. It is found that Skye sand is capable to treat arsenic-contaminated water to the WHO standard for the longest period, followed by TGS, Iron ore and NT red sands. Scoria sand is unable to treat water up to the WHO standard. Although, GFH, IOCS and IOCS-AOCS are capable to remove arsenic to an excellent level, however practically not suitable as they get clogged due to accumulation of finer particles in the filter bed. Also, it is found that artificial coatings enhance the arsenic removal capabilities, however susceptible to clogging.

An Eco-Friendly Procedure for Preparation of Activated Carbon as a Capture Material of Heavy Metals in Wastewater

This study aims to prepare an activated carbon from environmentally and inexpensive materials such as banana peels. The synthetic activated carbon has been employed in the capture of heavy elements e.g., copper (Cu), zinc (Zn) and cadmium (Cd) ions from wastewater. The spectroscopic (Fourier-transform infrared; FTIR) and morphological surface (scanning electron microscopy; SEM) investigations of the activated carbon were assigned. Adsorption of mentioned heavy metals upon the activated carbon studies were performed with different parameters such as effect of contact time, initial concentration of the heavy metal and pH (2–10) of the solution. A comparison of the adsorption capacity of the synthetic activated carbon (dried banana peels) with different adsorbents previously used (dried fruits peels) for Cu(II), Zn(II) and Cd(II) ions removal from wastewater streams shows its observable efficiency over many other treated and untreated natural and synthetic adsorbents. The Cu(II) ions showed the highest removal efficiency followed by Cd(II) then Zn(II) ions.

ELIMINATION OF TOXIC ELEMENTS BY NATURAL AND SYNTHETIC ADSORBENTS

The adsorption of Zn(II) and Cu(II) onto siderite (S) and kaolin (K) and adsorption of As(V) ontobentonite (B) was studied. The chemical modification – precipitation of MnO2 on the kaolin (KM) andsiderite (SM) surface was used to improve the adsorption properties of natural materials for theirapplication in columns. In the batch tests the higher adsorption capacity was observed for the KMsample. The binary solution of Zn(II)/Cu(II) was percolated through the columns filled with quartz sand(QS) as a bearer of KM or SM. The effect of toxic elements removal reached in average 90 % for bothcolumns.The adsorption of As(V) onto natural bentonite (B) and synthetic magnetic particles (MP) was studiedby batch as well as column tests. Whereas the B sample did not perform good adsorption properties inbatch test, in dynamic conditions its effect was comparable with MP. The effect of As(V) removal wasstudied in a number of series with different materials beddings and cycles repetitions. The resultsshowed that the most effective was the column filled with QS+B+MP containing more coarse-grainedfraction of bentonite. In the second cycle its removal effect reached 60 % of As(V) elimination from thesolution.

Adsorption of Pb(II) from wastewater by natural and synthetic adsorbents

Water pollution is a major concerned to the human health. Most of the global surface water is contaminated with heavy metals, has become a serious problem today. Particularly, Pb is highly toxic and directly associate with health risk such as damage to kidney, liver and central nervous system. In this review article, removal of lead utilizing various adsorption methods is described. Such as, natural (e.g. shells and peels corncobs, mushrooms, dairy manure, orange, apple, custard apple, peanut, eggshells, banana, eggplant, fish scales algae); activated carbon (e.g. sugar cane, orange peel, chicken feather fruit seed and bentonite); nano-composite, magnetic nanomaterials, polymer composite; chitosan, cellulose, clay, lignin, calcite, resin and chemicals are presented.

Optimization of Adsorption Parameters for Ultra-Fine Calcite Using a Box-Behnken Experimental Design

Removal of heavy metals from wastewater is a significant issue because it prevents environmental-based concerns and impacts a large number of diseases and disorders. Many low-cost natural materials have been offered recently as possible precursors to commercial synthetic adsorbents. Ultra-fine calcite, one of these natural materials, has been investigated as a potential commercial adsorbent. Response surface designs are effective experimental techniques to investigate the heavy metal adsorption capacity of ultra-fine calcite. In the present study, one such response surface design, Box-Behnken, is used in order to optimize adsorption factors, such as pH level, initial metal concentration, stirring rate and adsorption time, and to determine the heavy metal capacity of this adsorbent. Our results show that the proposed methodology is an effective approach to optimizing the adsorption process and to maximize the heavy metal capacity.

Chitin from Portunus pelagicus (Crab) Shells as a Potential Adsorbent for Common Water Contaminants

Portunus pelagicus (crab) shells are considered a delicacy by many throughoutAsia. In most instances, the specie is highly prized as the meat is sweet. This studywas conducted to investigate the common water-contaminant adsorption capacityof chitin from Portunus pelagicus (crab) shells under different concentrations and compare its adsorption capacity with that of standard adsorbents.Demineralization was done to the shells using a standard HCl solution for 24hours to remove all existing minerals. The demineralization and deproteinationprocesses were based on the methods of Takiguchi (1991). Demineralizedand deproteinized crab-shell was subjected to qualitative tests to confirm thepresence of chitin using the methods of Richards and Campbell. The percentageadsorption activities were determined by comparing the concentration of thecontaminants before and after chitin were added to the solution. It was observedthat adsorption activity increases as concentration of chitin increases. Thus, itis more effective in higher concentrations. The results revealed that chitin fromPortunus pelagicus offer adsorption sites for the common water contaminantssince it is composed of chitin fibrils, arranged with units of amino groups andoxygen that makes it ideal for adsorbing different materials; hence, it can be anefficient substitute for synthetic adsorbents for common water contaminants forit does not pose any danger to human health.Keywords: Marine biology, portunus pelagicus, turbidity, demineralized, deproteinized,chitin, absorption, pH, mercury, lead, experimental design, Philippines