On the basis of the enzymatic (phosphatase) activity and microbiological analysis as well, the influence of the oil refinery "Vital" - Vrbas (Serbia, Yugoslavia) wastewater to the recipient DTD (Danube-Tisza-Danube) canal water from the microbiological point of view was determined. In addition the efficiency of the factory's waste water purification plant was estimated. The obtained results of the complex microbiological-enzymological analyses indicated a good water quality at the point where the refinery's water supplies plant is situated (site 1). Very low water quality was determined downstream (site 4) and upstream (site 2) from the inflow of the refinery's wastewater's inflow. The later results might indicated the influence of an unknown pollutant in the region. However, the obtained O/H index value suggests that the self-purification ability of the canal waters is still preserved.

Previous studies clearly indicated that membrane enzymes - ATPases i.e. Na, K-ATPase and Mg-ATPase, responded to presence of various organic and inorganic pollutants. In this work effect of mercury and cadmium on these enzymes activities was investigated in synaptic plasma membranes partially immobilized on microliter plate. Comparing those activities with the control enzyme activities obtained with native and partially immobilized mambranes it was concluded that: a. both metals exerted a concentration-dependent inhibition of investigated enzymes, b. for partially immobilized membranes estimated half maximum inhibition (IC50) values for Na, K-ATPase were IC50 (Hg) = 0.9 micromol/cubic cm, IC50 (cd) = 35 micromol/cubic cm and for Mg - ATPase IC50 (Hg) = 3.5 micromol/cubic cm, IC50 (Cd) = 36 micromol/cubic cm; for native membranes IC50 for Na,K-ATPase were IC50 (Hg) =3.3 micromol/cubic cm, IC50 (Cd) = 2 micromol/cubic cm and for Mg ATPase IC50 (Hg) = 2.3 micromol/cubic cm, IC50 (Cd) = 0.2 mmol/cubic cm. Obtained results indicate avaibility of microtitar plates for partially immobilization of membranes with aim to form a new biosensor for heavy metals detection.

This paper deals with microbiological and chemical analysis of waste mud, produced in wastewater purification plants of the oil refinery. After digest, mud is removed to the filter press. Compressed mud is placed and stored on the storage yard. Content of organic, anorganic and oil matters and also heavy metals contents were determined. Microbiological analysis comprised determination of total count of aerobic organotrophic organisms and many physiological groups of bacteria. As the indicator of the general biochemical activity, enzymatic (dehydrogenase and phosphatase) activities were determined. Waste mud was mixed with soil (chernozem) in 20%, 40% and 60% amount relations. Changes of activities and quantitative fluctuations of the present microflora were observed after 15 and 30 days. Gained results should enable assessing of using-ability of waste mud in soil-quality improvement, in the sense of its utilization as the fertilizer.