The paper presents the results of studies on detection, occurrence and differentiation of the waterborne bacterial potential pathogens from Staphylococcus genus in the water of Wigry Lake watering places in north-eastern Poland. The samples of water were collected from June 1995 to September 1999 at one-month intervals, during bathing season. Eight sampling stations were selected in the most attended watering places of the lake, situated near landing stages, camping sites and holiday resorts were investigated. The watering places in the northern part of Lake Wigry (called Ploso Northern) showed the highest number of waterborne bacterial pathogens from Staphylococcus genus. The most numerous were species: Staphylocorcus capitis, Staphylococcus cohnii, Staphylococcus len/us and Staphylococcus xylosus. Pathogens from Staphylococcus aureus species identified in I 0% of water samples in the absence of faecal bacteria from Escherichia coli species (in 100 crn' of water). The Czarna Hańcza River, which brought a lot of purified sewage from Wastewater Treatment Plant in Suwałki to northern part of Wigry Lake has immense influence on the pollution of this part Wigry Lake.

One of the prerequisites for sustainable development is integrated waste management, including sewage sludge. Besides its good fertilization properties, sewage sludge, which is an inevitable by-product of sewage treatment, accumulates toxic chemical substances and dangerous pathogenic and toxicogenic organisms. Uncontrolled introduction of sewage sludge into soil might pose a serious threat to food chain and natural soil microflora. This in effect might disturb the ecological balance in a particular ecosystem. This study presents author’s own investigations of the sanitary conditions of sewage sludge and the conditions after the processes of aerobic and anaerobic stabilization. The investigated sewage sludge originated from a municipal wastewater treatment plant. The sewage sludge samples were transferred onto proliferation and diagnostic media. The results of the analysis obtained in this study confirmed that sewage sludge is a material which is rich in microorganisms, including pathogenic bacterial species such as: Escherichia coli and Salmonella typhimurium. Mycological tests demonstrated that sewage sludge is a material which is conducive to proliferation of yeast-like and mould-like fungi, among which both pathogenic and toxinogenic species can be present. Quantitative analysis of the investigated sewage sludge demonstrated that the processes of stabilization reduce the content of microorganisms but they do not guarantee product safety in sanitary terms. A huge variability and variety of biological composition points to the need for further research in the field of sanitary characteristics of sewage sludge and survival rate in microorganisms from different types of sewage sludge.