Sawdusts of hardwood - oak and black locust, modified with formaldehyde and/or alkali solution, were used as adsorbents zinc ions from model water. The influence of concentration of alkali solution for modification, on zinc ions adsorption efficiency were investigated. Batch adsorption tests were conducted on ambient temperature. Langmuir and Freundlich adsorption isotherm equations were determinated for some adsorbents investigated. Good improvement of adsorption characteristics is achieved by modification of sawdust with alkali. Modification of sawdusts only with formaldehyde results with good prevention of leaching of organic substances as well as poor increase of adsorption efficiency.

In this study possibilities for application of natural aluminosilicates, zeolites in the wastewater treatement has been investigated. Under the laboratory conditions the pilot experimental a column filled with aluminosilicates was established. Technological characteristics of the system were estimated by wastewater flow monitoring and calculation of Darcy filtration coefficient.

This study investigates the effect of pH, temperature, contact time and initial metal concentration on Cu++ ions removal from water solutions, using biomass of Lagenaria vulgaris skin (LV). With higher pH, the efficiency of copper sorption increases and reaches its maximum at pH 7.0. Temperature has negative effect on sorption process due to its exothermic properties. Biosorption efficiency increases with time and reaches equilibium after 40 min. Increasing initial copper concentration gives an increase in biosorbent sorption capacity, and a proportional decrease in treatment efficiency. Obtained results have shown that LV based biosorbent is an efficient and available mean for toxic metal removal from natural and waste waters.

Anionic clays (layered double hydroxides) comprise positively charged layers with at least two different metal cations, octahedrally coordinated by hydroxyl groups. The positive charges of layered double hydroxides are counterbalanced by interlayer anions. The interlayer anions and water, which fill the interlayer space, are often labile. Therefore, anionic clays exhibit anion exchange capacity (AEC). Anionic clays which have a high surface area and a high anion exchange capacity, are potential adsorbents for anionic contanimants, such as the oxyanion of chrome. The adsorption study of chromium (VI) from aqueous solutions by natural cationic clay mineral (kaolinite, montmorillonite, etc.) was not given much attention, perhaps due to the fact cationic clays have negatively charged layers and clay mineral surface shows no affinity for oxyanion of chrome.