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The processes used to remove heavy metals from inorganic wastewater have in general low efficiency. The use of activated peat obtained by using a process similar to a cation exchange reaction increases the removal efficiency up to five times when compared with peat “in natura”. The main objective of this work is to show the fundamental mathematical model, governed by diffusion process and the algorithms utilized to design the batch and the continuous feed stirred tank reactors or in some cases a fixed bed reactor. The principal dimensions of these equipments are obtained from the knowledge of the activated peat's cation exchange capacity used in the process, and the main chemical characteristics of the heavy metal ion contained in the wastewater. Besides, two important parameters are also included: the ion concentration and the efficiency of the process obtained from laboratory kinetics experiments. For example Pb+2 is removed l:rom a wastewater at a concentration of 50g/m3 in five minutes or less, with an efficiency of 98%.

The reduction of the heavy metals concentration in liquid effluents is difficult and the existing methods available are expensive and their efficiencies ate in general low. The normal procedure adopted is based on the recirculation of the “chorume”, sometimes with a high content of heavy metals, into the liquid effluent flux of the central processing unit having in general a biological treatment. Depending on the heavy metal concentration the efficiency of the biological process decreases, or in certain cases, collapses completely. Activated peat by using the acid process or the one developed by the Universidade Federal de Sergipe and Instituto de Tecnologia e Pesquisas de Sergipe becomes an excellent heavy metals sorbent, which in certain analytical conditions has a very high efficiency. The overall process is controlled by diffusion and is governed by a first order kinetics. The use of activated peat shows in several situations that this process is a feasible alternative to getting the reduction of heavy metals concentrations in simulated effluents with one or more cations. Preliminary results show a significant matrix influence. The organic matter presence in the effluent may alter the sorption efficiency depending on its composition. The optimum analytical condition varies with the effluent quality and promotes the highest efficiency in the reduction of heavy metals concentrations.

Modifications of Azospirillum lipoferum Sp Br17 were observed when it was incubated with the organochloride insecticide Dicofol. In experiments run under non N2 fixing conditions, cellular volume measured in a Coulter Counter Channalyser was reduced immediately after addition of pesticide. Cell counts, made in a Coulter Counter increased during 12 hours after addition of 250 and 500 ppm of Dicofol. Cell viability was reduced by 1 hour incubation in Dicofol concentrations of 10 to 500 ppm, These results suggested that one of the first consequences of Dicofol action was cell disruption, Incubation for 1 to 7 days showed that maximum cell counts, protein content, average cell volume, and viability were lowered by increased Dicofol concentrations. Growth was totally inhibited by 250 and 500 ppm of Dicofol but in some experiments a latent growth was observed, suggesting selection of resistant mutants. Experiments under N2 fixing conditions showed that nitrogenase activity was inhibited by increasing Dicofol concentrations of up to 1000 ppm, but in some experiments was stimulated by a concentration of 1 ppm, Microscopic obser vations of Azospirillum morphology in the presence of Dicofol showed cyst like formations that may be an induced resistance mechanism.