Pollution of rivers and reservoirs with sewage is a serious problem nowadays. Waste from the central sewerage of large cities and other settlements needs constant cleaning, so the use of filter systems and biological cleaning methods is a must.
What is activated sludge?
Silt, which is active against pollutants, is used in domestic septic tanks, in industrial plants and in urban sewer systems. Activated sludge, or the biocenosis of zoogenic accumulations, is a complex of bacteria and other microorganisms that use human waste for nutrition and reproduction.
Microorganisms and bacteria absorb organic matter from the total mass of wastewater and process it into simpler compounds in the process of oxidative reactions. For the productive work of activated sludge, it is necessary to create certain conditions: the waste liquid must have a temperature of at least +6 degrees. Effluent should not contain many toxic substances or refined petroleum products. Activated sludge is a complex of living organisms that can die with a sharp change in the environment. Low temperatures can slow the growth of bacteria, but not kill them.
Silt concentration
Productive wastewater treatment is possible only if the polluted mass is exposed to a sufficient number of microorganisms. The concentration of biologically activated sludge is measured as follows: the amount of dry matter of biomass per unit volume is determined. 100% is the total mass of all liquid in the container. The activated sludge concentration is measured as a percentage.
Oxidation processes in high concentration sludge will be much faster, waste processing will become more productive.
Silage composition
Activated sludge is a mass consisting of flakes 1-3 mm in size. Flakes are formations that consist of bacteria combined with polysaccharides. Activated sludge contains biologically active components, dead microorganisms, suspended particles of inorganic compounds, fiber and other polysaccharides.
Each group of bacteria specializes in the oxidation of certain substances. Filamentous bacteria, nitrifying bacteria and flocculent bacteria oxidize organic carbohydrates and nitrify compounds. bacteria p. Pseudomonas are able to oxidize fatty acids, paraffins, alcohols and hydrocarbons. Oil refinery products, naphthenes, phenols, aldehydes are oxidized by bacteria p. Brevibacterium. Bacteria from p. Bacillus are used forsplitting of aliphatic hydrocarbons. bacteria p. Cellulomonas oxidize cellulose.
Microorganisms of activated sludge can also be of a fungal nature. Molds and yeast fungi do an excellent job of breaking down complex oxidizable substances and toxic compounds.
Activated sludge monitoring
The activity of the sludge may decrease over time, it all depends on the medium coming from the runoff water. In order for the cleaning process to be productive, it is necessary to monitor the condition of the bacterial environment of the sludge.
Bioindicator control of activated sludge is carried out using microscopic analysis. Features of the structure and composition of the sludge are identified, and a detailed report and a list of bacterial species are compiled. The predominance of microorganisms of a certain group indicates a favorable development of the bacterial environment, since bacteria must respond to the incoming runoff mass by changing their composition and quantity. For example, when sewage with a high sulfur content enters, thionic bacteria and sulfur bacteria begin to actively develop.
By the composition of activated sludge, one can not only determine the productivity of processing, but also make a forecast of the development of the environment, provided that the regime of sewage inflow of the same composition is maintained.
Industrial Wastewater Treatment
Waste water, which is the waste of industrial enterprises, contains a large amount of toxins and complex chemical compounds. Getting into the environment, effluents cause damage to living organisms and plants,contaminate groundwater and air. Therefore, each industrial enterprise develops a plan for the disposal of production waste.
Before the biological oxidation of wastewater, the liquid flow undergoes mechanical cleaning. Filters separate large solid particles of impurities, which are deposited in separate containers. After biological treatment, the liquid is disinfected.
Some businesses get useful components from stock waste. The biomass that comes from the wastewater treatment process can be valuable. Substances used in the production of fertilizers, medicines and other useful substances are released. The possibility of using waste depends on the type of production and the chemical composition of the waste mass. The introduction of activated sludge into industrial wastewater is an inexpensive and productive way to treat waste. This is currently the most popular waste disposal method.
Analysis of environmental change sludge
Research of sludge on the composition is carried out in a special laboratory. To do this, a sample is collected in a clean, opaque container. Analysis of activated sludge is carried out 1-2 times a week for 2 months. Sludge efficiency is determined by the following indicators:
- dry matter concentration;
- phosphorus content;
- enzymatic activity productivity;
- respiratory activity;
- silt flakes condition.
Determination of the composition of sludge is carried out using microscopes of different power. A reagent of a certain composition is introduced into the mass of activated sludge. For several daysthere is a change in the composition of the sludge and the growth rate of certain types of bacteria. The size of the flakes and the concentration of individual bacteria are evaluated.
Activated sludge treatment steps
Neutralization of complex organic compounds and their oxidation to simple components takes place in several stages:
- Anaerobic oxidation.
- Aerobic oxidation.
- Settling of the mass in the sump.
- Biological treatment with the participation of microorganisms of various nature.
- Separation of liquid from sludge in the sump.
- Activated sludge dewatering.
- Drying sludge.
Solid particles, debris and sand are removed before the main cleaning. The size of suspended particles at the outlet depends on the throughput of the filters. The material collected from the filters is incinerated.
During the primary cleaning process, the remaining solid particles are concentrated at the bottom, and light fat-containing substances spread along the surface. The sediment and the film are removed from the total mass, and the liquid enters the next container for the next cleaning step.
Activated sludge is used for secondary treatment. Water enters the tank along with the sludge, which in the process of interaction is filled with oxygen. Such an environment is an ideal condition for the development of bacteria that feed on the organic substances of the liquid, purifying it and releasing carbon dioxide and water. The amount of sludge is constantly growing, as bacteria actively multiply. Excess activated sludge must be periodically removed from the tank.
Anaerobic andaerobic activated sludge bacteria
Nutrition and reproduction of anaerobic bacteria occurs without the active participation of oxygen. More precisely, oxygen is used in the process of oxidative reactions, which is part of oxygen-containing acids formed from complex organic substances.
Oxidation by anaerobic bacteria is identical to the natural processes of decomposition of organic matter. Only these processes proceed much faster due to the high concentration of bacteria in the activated sludge medium.
As a result of the decay of organic matter, carbon dioxide and methane are released.
The processes of oxidation of aerobic bacteria occur with the active participation of oxygen contained in the liquid. To maintain the amount of oxygen necessary for the life of bacteria, a septic tank should be equipped with a special compressor or aerator. Aerobic activated sludge is an environment that needs a constant and continuous supply of oxygen.
Aerobic bacteria break down complex organic substances into simpler ones in a shorter time than anaerobic bacteria. It is necessary to clean such a septic tank less often, since the amount of solid waste is much lower. The downside is that a septic tank with aerobic oxidation is much more expensive than an anaerobic one.
If the drain fluid stops flowing into the sewer or septic tank, over time, the bacteria will die from a lack of nutrient medium. Starting the septic tankwill be possible only after the introduction of a new active bacterial medium.
Treatment and use of waste activated sludge
Activated sludge is a valuable substance. Its content may contain elements such as phosphorus, zinc, nitrogen. These trace elements can be useful in agriculture. The use of activated sludge as a fertilizer is possible only if there are no impurities of heavy metals in the composition. Concentrating in plant tissues, metals make vegetables and fruits hazardous to he alth.
Spent activated sludge is a dehydrated mass. If there are extraneous unnecessary impurities, then the spent dehydrated sludge is cleaned or disposed of. Purification of biologically activated sludge is done only in cases where it is advisable. Thanks to chemical reactions, toxic elements are removed from the mass of sludge. Heavily contaminated activated sludge, which has no industrial value, is incinerated.
Where to buy activated sludge for cleaning
If you are going to install a septic tank on your personal plot on your own, then in the process of arranging the sewer system, the question may arise with the purchase of activated sludge.
Biological latrines and septic tanks are sold as liquids or dry substrates. You can buy them in the department of household chemicals for giving. The price depends on the volume of packaging and the composition of the mixture. The package describes in detail how to use the product, what volume the container is designed for and for how long the productivework of biological composition.
When buying a wastewater treatment agent, you should carefully read the composition of the options offered. It is better to use products with aerobic bacteria. For their active reproduction and nutrition, air flow is necessary. Oxidative processes allow you to get rid of a larger amount of impurities compared to anaerobic bacteria. And the sediment can be used to fertilize the soil.
Optimal conditions for the full functioning of activated sludge
Observance and maintenance of favorable conditions for the development of activated sludge is the key to the successful productive operation of the treatment plant. The temperature at which active reproduction and nutrition of colonies of bacteria and fungi takes place is + 20-27 degrees Celsius. If the ambient temperature is less than +6 degrees Celsius, the action of microorganisms becomes less productive, and the rate of wastewater processing decreases.
When changing the composition of the waste, productivity also falls. Bacteria need a certain amount of time to rebuild. If, for example, refined products are introduced into the bacterial environment, and there are few bacteria responsible for the oxidation of such complex substances, then a certain amount of time must pass for their active reproduction. If a large amount of toxic substances is introduced, the bacterial environment may die.
The composition of the incoming liquid should contain a sufficient amount of organic substances: carbohydrate, nitrogen, phosphorus, sulfur, manganese. Aerobic bacteria require oxygen to function properly.care must be taken to continuously feed it into the liquid.
In conclusion
Recycling household waste, based on the processes of decay and oxidation with the help of bacteria, is a natural way of disposal. The safety and productivity of using activated sludge for wastewater treatment makes the process convenient and environmentally friendly, regardless of the application of this waste treatment method.
