OUR WATERS, POLLUTION, PROTECTION AND RECYCLING....continued

Due to progressing pollution, bathing in rivers, ponds, or lakes has become rather risky, drinking their water is dangerous. Technical requirements additionally changed the "water landscape". This atlas of transparencies at hand informs about the dangers to our waters, treats general questions of pollution and clarification of surface waters, shows the importance of analysis and control, describes the methods of clearing sewages, and discusses natural treatment of flowing waters as well as steps to redevelop lakes.

Running and Standing Waters in Land Developed and Cultivated by Humans. Dynamic hydrosphere, diagram - Natural water cycle, diagram - Natural dynamic of water: waterfall - Clear mountain creek. Natural purification and oxygenation - Big stones on the banks of mountain creek - Creeks and rivers coming from wooded areas ensure steady flow and deep temperature - Correcting of the course and covering the banks with concrete depopulates a river and lowers the neighbouring ground water level - Cutting down trees and shrubs on river banks, a wrong step.

Natural Structure of a Running Water. Subdivision of a running water into head-waters, creek, river, and brackish water region, diagram - Morphology of a running water with upper, middle, lower reaches including erosion and sedimentation regions, diagram - Build-ups, weirs protect from high water and serve to raise the ground-water level - Line of water-level duration and profile of bank vegetation - Change of the transverse profile to shade the water and lower its temperature, diagram - Installation of small steps on the bed to raise the water-level - a) steps of local stone, - b) groynes and disturbing stones support the dynamic development of the water - Protected by trees and shrubs, the water gradually runs a natural course with undercut bank and slope. - Fish ladders improve biotope - Measures to protect flat and steep coasts, diagram - Active cliff - Marram grass (Ammophila arenaria) fixes shores and dunes.

Water Tests and Survey. Test of water quality: determination of temperature - Test of water quality: electrometrical determination of oxygen content, conductivity, and pH - Taking water samples: measuring contents of oxygen, conductivity and pH with electric gauge - Analysis of water in the laboratory - Fully automatic testing of water in laboratory installed close to a river.

Grades of waters. Grade I: pure water zone of a mountain creek (oligosaprobic zone) - Bioindicators (organisms) of grade I (oligosaprobic zone) - Grade II: moderately polluted surface water (beta-mesosaprobic zone) - Bioindicators (organisms) of grade II = Moderately polluted zone (beta-mesosaprobic zone) - Grade III: heavily, critically polluted surface water (alpha-mesosaprobic zone) - Bioindicators (organisms) of grade III = heavily polluted zone (alpha-mesosaprobic zone) - Grade IV: extremely polluted superficial water (polysaprobic zone) - Bioindicators (organisms) of grade IV = extremely polluted zone (polysaprobic zone) - Extremely polluted water (grade IV, polysaprobic zone) of an oasis - Water grades between source and mouth of a river, graph - Subdivision of a running water according to degree of organic pollution, grades of saproby, saproby index, identifying colours, and oxygen minima - Chemical criteria for grades of biological pollution, table - Classification of running waters according to bacteriological findings.

Pollution of Waters by Introduction of Sewage. Cycle of organic substances in the water, diagram - Mouth of a sewage drain on the Mediterranean shore - Same place of shore with bathing persons. Extreme danger of infection ((cholera, typhoid, paratyphoid, enteritis) - Introduction of unprocessed sewage of a town with 100 000 inhabitants into a river - Introduction of dairy sewage into a standing water - Introduction of dyes into a brook - Creek, totally destroyed by hot effluents containing stains - Creek, extremely polluted with domestic sewage and waste - Effluents of an iron factory colour the water and the bed red-brown - Destruction of natural biocoenosis by deposition of non-ferrous metal sludge - Use of wood for poison dump killed trees by toxic quantities of chromate - Introduction of liquid manure containing proteins causes formation of scum - Highly polluted effluents drawing out of cellulose plant - Ligninsulphonic acid contained in cellulose effluents colours creek dark - Consequence of introducing cellulose effluents: bacteria (Sphaerotilus natans) and fungi (Leptomites lacteus) produce great quantities of mucilage - Oil floating on water - Physical, chemical, and biological processes decompose oil floating on water, diagram.

Eutrophication of Lakes and Running Water. Eutrophication of a river by introduction of phosphates and nitrates - Eutrophication (lack of oxygen) and pollution cause death of fish - Completely eutrophicated lake due to introduction of domestic sewage and liquid manure - Odours caused by microorganisms forming alga bloom, diagram - Mass reproduction of algae I: Euglena viridis - Mass reproduction of algae II: Asterionella formosa - Production of methane and hydrogen sulphide in the marginal zone of an eutrophicated lake - Mass reproduction of jellyfish in the sea indicates unbalanced biological equilibrium - Jellyfish, photograph.

Redevelopment and Restoration of Lakes. Unspoiled oligotrophic mountain lake - Polysaprobic lake with extreme alga growth - Phosphorus cycle in a lake, diagram - The lake, a phosphate trap: cause of accelerated refertilisation - trophication spiral, diagram - Reoligotrophication of lakes due to external and internal treatment, reduction of nutrient spiral to normal nutrient cycle, diagram - Reoligotrophication I: installation of deep water drain for various zones - Installation of deep water drain - Percentage biomass of the various alga groups after deep water drainage - Reoligotrophication II: addition of oxygen to deep water (hypolimnion), diagram - Reoligotrophication III: injection of nitrates for biochemical oxidation of reduced sediments - Manipulation of food chain: purposeful fishing of zooplankton-eating fish reduces algae-eating zooplankton - Manipulation of food chain: reduction of zooplankton-eating fish increases number of predaceous ones, diagram - Fishing manipulates food chain.

Purification and Protection of Waters, Methods. Removal of organic substances by mechanical and biological processes in sewage plants and recipients, diagram - Structure and function of a sewage plant - Retention of coarse particles by the grit - 1st Cleaning step - Size of particles in sewage, diagram - Fluctuations of urban sewage quantity during 24 hours, diagram, - Long sand catch with gauge for water quantity - Basin for primary sedimentation with clearing bridge - 2nd Cleaning step - Drip tower filled with synthetic elements - Section through a drip tower, diagram - Decrease of biochemical oxygen demand during 5 days indicates biological clarification - Biological clarification of sewage with diving cylinders. - View on a group of drip towers filled with synthetic elements to clear effluents from a paper mill - Drip tower with water circulation and filled with synthetic elements - General view of a modern full biological activated sludge plant - Turbines swirl and aerate - Aeration of activated sludge by bubbles - Aeration of activated sludge by tubes - Organisms in the activated sludge basin, diagram - Organisms in activated sludge I. Vorticella microstoma - Organisms in activated sludge II. Rotaria rotatoria - Clarification of sewage with pure oxygen, diagram - Supply with pure oxygen in closed system by surface aeration (Detroit, USA) - Biocoenosis of activated sludge treated with pure oxygen I: mass reproduction of Carchesium polypinum - Ditto. II: Vorticella convallaria - Basin for secondary sludge in big oxygen treatment sewage plant (Detroit, USA) - Flowover of the purified water - Function test by determination of sludge volume, sludge weight and sludge index, diagram - 3rd Cleaning step - Phosphate elimination by chemical precipitation in sewage plant - Denitrification eliminates nitrogen - Anaerobic sludge fermentation - Fermentation (digestion) of sludge in fermentation towers - Fermentation (digestion) in separate towers, diagram - Efficiency of various clarification steps in a sewage plant.

Acidification of Surface Waters - Biocides in Waters. Effects of sour rain on aquatic ecosystems, diagram - Lake in Sweden with high acidification - Toxic pH-limit in acid and basic range, diagram - Summary of various contacts of biocides with water, diagram - Accumulation of biocides in the food chain of various aquatic organisms - Direct entry of biocide sprays into the water.

Drinking water - Summary. Future demand of water in Sweden (industrial, domestic), diagram - Introduction of surface water into a drinking water plant - Precipitation of unwelcome substances - Filtration with sand - Inconsiderate exploitation of water - Good use and processing of water.