There were presented technological and ecological aspects of biogas quality evaluation and introduced an overview of the limits of its selected parameters. There were characterized analytical methods for determining the basic composition of biogas, hydrogen sulfide, ammonia, condensation, dust, oils, siloxanes, and aggregated content of sulfur, chlorine and fluorine. The result of comparative analysis and literature studies are proposes of the most adequate to the studies of biogas -analytical methodologies.

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Application of phytoremediation process for the purification of the environment, particularly of surface water (running or standing) may be a future alternative to existing standard purification methods, in particular for heavy metal removal. Numerous hyperaccumulators are known which can be used for the purification of water, soil or sediment such as Salvinia or Lemna lemnids, occurring in temperate climates, and thus on the territory of Poland. Ability of mercury accumulation by Salvinia natans and Lemna minor was analyzed. The phytoremediation ability of lemnids was compared depending on their origin -commercial (artificial) cultures and those obtained from the natural environment. Phytoremediation process was carried out for a period of 14 days for the concentration of 0.15 mg Hg/dm 3 and 0.2 mg Hg/dm 3 . It was found that both Salvinia natans and Lemna minor show a significant increase in biomass in the presence of mercury, even up to 76% for Lemna minor and 40% for Salvinia natans. The result of this increase was incorporation a considerable amount of mercury in the tissues of plant. The quantity of mercury in plants biomass was in the range of 41.16-115.28 mg Hg/kg DM, while in the control samples -only 0.2-0.6 mg Hg/kg DM.

A B S T R A C TPhytoremediation may be an alternative to traditional methods of removing heavy metals from the aquatic environment. In order to remove mercury at a concentration of 0.3 mg/L from Hoagland medium, two species of pleustophytes were used, namely Salvinia natans and Lemna minor. Some homogeneous cultures and another one mixed in a weight ratio of 2:1 were used. The physiological condition of the plants was controlled after 7, 14 and 21 d by evaluating biomass growth, analysing the changes in the amount of total protein and assimilation dyes. At the same time, the level of the mercury content in the base and plant tissues was controlled. The increase in biomass during plant exposure to mercury was up to 190% compared to baseline. Accumulation of mercury in plant tissues to 238.34 mg/kg d.m. , contributed to a significant reduction in its concentration in the medium. The bad condition of the plants led to an attempt to support phytoremediation by micro-organisms taking an active part in the transformation of mercury. For this purpose, epiphytic bacteria, accompanying S. natans, which are resistant to mercury at a concentrations of 0.3 mg/L, were isolated. Studies indicate the possibility of using the plants S. natans and L. minor to remove mercury compounds from the aquatic environment, while providing a basis to determine the principles of design and operation of Lemna ponds, especially when the process is simultaneously stimulated by those bacteria that are resistant to high concentrations of mercury.