Effects of Natural Zeolites on Bioavailability and Leachability of Heavy Metals in the Composting Process of Biodegradable Wastes

The article presents the results of research on reducing the concentration of heavy metals, such as copper and nickel, on natural zeolite in comparison with synthetic zeolite and chemically treated natural zeolite. The reduction of the content of specific types of heavy metals from aqueous solutions was investigated by the method of sorption kinetics. The results indicate the ability of natural zeolites to compete with synthetic zeolites.

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Stabilization of heavy metals in sewage sludge composting process

Water Science & Technology ◽

10.2166/wst.2001.0591 ◽

2001 ◽

Vol 44 (10) ◽

pp. 95-100 ◽

Cited By ~ 10

Author(s):

K.-Y. Chiang ◽

S.-D. Yoi ◽

H.N. Lin ◽

K.-S. Wang

Keyword(s):

Heavy Metals ◽

Sewage Sludge ◽

Total Concentration ◽

Physicochemical Characteristics ◽

Limit Values ◽

Sludge Compost ◽

Composting Process ◽

Agricultural Applications ◽

Maturation Rate ◽

Sludge Composting

This study investigated the stabilization of heavy metals in a sewage sludge composting process using kaoline addition. The results indicate that the temperature increased rapidly to the thermophilic phase (>55°C) at day 1. The additives enhanced the rate of biodegradation and microbial activity during the co-composting process. The changes in pH (ranging from 8 to 8.5) and electrical conductivity (EC) (≤3 mS/cm) were in compliance with the best conditions during the co-composting process. The C/N ratio was determined in each co-compost sample as an indicator of the co-compost maturity. From the end product of the co-compost experiment, changes in the ratios indicate that the additives promote the co-compost maturation rate. Based on the physicochemical characteristics of the co-compost, the potential use for sewage sludge resource recovery as manure is suggested. The total concentrations of Pb, Cd, Cr, Cu, and Zn in the co-compost product were far below the limit values for agricultural use. The leachability of Pb, Cu, and Cr decreased with increasing co-composting time. That is, the kaoline additive has an inhibitory capacity for leaching heavy metals. The Cd concentrations in the sludge compost were below the detection limits. Because the total concentration of Zn was high in the sludge compost and most soluble Zn was leachable, the leachability of Zn ranged from 25% to 29%. As a result of the physicochemical characteristics and heavy metal stabilization, the selected additive was shown to improve the sewage sludge compost quality and provide information for agricultural applications.

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Removal of Heavy Metals from Model Mine Wastewater by Adsorption Using Mongolian Natural Zeolites

JOURNAL OF CHEMICAL ENGINEERING OF JAPAN ◽

10.1252/jcej.12we137 ◽

2013 ◽

Vol 46 (1) ◽

pp. 50-55 ◽

Cited By ~ 4

Author(s):

Ryuichi Egashira ◽

Saori Tanabe ◽

Hiroaki Habaki

Keyword(s):

Heavy Metals ◽

Natural Zeolites ◽

Removal Of Heavy Metals ◽

Mine Wastewater

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Natural zeolites effect on heavy metals immobilization in soil

NATO Science Series - Phytoremediation of Metal-Contaminated Soils ◽

10.1007/1-4020-4688-x_13 ◽

2006 ◽

pp. 319-326

Author(s):

C.H. Barbu ◽

l. Oprean ◽

C. Sand

Keyword(s):

Heavy Metals ◽

Natural Zeolites

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Treatment of metals-contaminated wastewaters by use of natural zeolites

Water Science & Technology ◽

10.2166/wst.1999.0638 ◽

1999 ◽

Vol 39 (10-11) ◽

pp. 115-122 ◽

Cited By ~ 46

Author(s):

S. K. Ouki ◽

M. Kavannagh

Keyword(s):

Heavy Metals ◽

Metal Removal ◽

Low Cost ◽

Exchange Capacity ◽

Natural Zeolites ◽

Al Substitution ◽

Metals Removal ◽

Exchange Material ◽

Na Ions ◽

Competing Ions

This paper assesses the potential of natural zeolite utilization as a low-cost in exchange material for heavy metals removal. Two natural zeolites, clinoptilolite and chabazite, have been evaluated with respect to their selectivity and removal performance for the treatment of effluents contaminated with mixed heavy metals (Pb, Cd, Cu, Zn, Cr, Ni and Co). The effects of relevant parameters such as chemical treatment, metals concentration, pH, and presence of competing ions were examined. The results showed that the received zeolites contained exchangeable K, Ca and Na ions, but exposing them to concentrated NaCl solutions converted them to a homoionic state in the Na form which improved their exchange capacity. Clinoptilolite and chabazite exhibited different selectivity profiles for all metals studied except for Pb for which both zeolites performed exceptionally well. The results also showed that chabazite exchange capacity is superior to that of clinoptilolite mainly due to the higher Al substitution of Si which provides chabazite with a negative framework favourable to higher exchange capability. The pH was found to have an effect on metal removal as it can influence both the character of the exchanging ions and the zeolite itself. Overall, the removal mechanism was controlled by ion exchange and precipitation was proven negligible.

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