Peculiarities of clarifiers’ reconstruction at waste water treatment plants

The article reveals the ways in which the reconstruction of clarifiers for wastewater treatment plant can be performed. One of the most common method is bioflocculation that means use of corresponding properties of excess activated sludge or biofilm, which both have in its composition so called extracellular biopolymers that determine the spatial structuring and bioflocculation of cell formations. Multiple researches showed that use of surplus sludge as bioflocculant provides increased efficiency of sedimentation in any waste water up to 85–90% and reduce biochemical oxygen demand (BOD) in the clarified water by 40–50%. The other method to be implemented for reconstruction of clarifying facilities is thin-layer modules to raise the efficiency of settling. Thin-layer modules can be used in a wide range of capacity of sewage works. The possibility of application depends on the structural size and condition of building structures, the amount of suspended solids and other parameters

Scientific approach and practical experience for reconstruction of waste water treatment plants in Russia

Protection of water bodies has a strict dependence on reliable operation of engineering systems and facilities for water supply and sewage. The majority of these plants and stations has been constructed in 1970-1980's in accordance with rules and regulations of that time. So now most of them require reconstruction due to serious physical or/and technological wear. The current condition of water supply and sewage systems and facilities frequently means a hidden source of serious danger for normal life support and ecological safety of cities and towns. The article reveals an obtained experience and modern approaches for reconstruction of waste water and sludge treatment plants that proved their efficiency even if applied in limited conditions such as area limits, investments limits. The main directions of reconstruction: overhaul repair and partial modernization of existing facilities on the basis of initial project; - restoration and modernization of existing systems on the basis on the current documents and their current condition; upgrade of waste water treatment plants (WWTPs) performance on the basis of modern technologies and methods; reconstruction of sewage systems and facilities and treatment quality improvement

Methods and solutions for galvanic waste water treatment

Currently galvanic sludge is considered as one of the most dangerous wastes, which are formed during purification of galvanic wastewater. The slimes of galvanic production are the most toxic industrial waste and sources of heavy metals emitted into the environment. Galvanic sludge belongs to the third hazard class; these wastes need to be deposited in special landfills for toxic waste. These polygons are complex and require significant costs. In this regard, there is a need for such methods of purification of galvanic sewage sludge, which may be used in other industries or will have fourth class of hazard or below. This article compares the main methods of purification of galvanic waste waters in general and galvanic sludge in particular, currently introducing new techniques for treating industrial effluents. One of them considers treatment of galvanic waste water by means of suspensions of ferriferous hydrosol that is an electric generated coagulant derived from waste forming, steel wool, etc. There is a sort of experience already acquired in some countries how to use of ferropericlase

Research for waste water treatment technology with low production of excessive active sludge

The article reflects the possibility to create a technological scheme of waste water treatment of domestic and similar type of sewage within minimal amount of excessive active sludge by means of bioreactors with immobilized feed. There are various aspects to be considered: technical, economic, social and ecological. According to the above it is strongly needed to provide a combination of proper waste water treatment, minimal sludge formation and the possibility for a further use of the sludge. One of the ways to achieve the goal above is to use an immobilized feed in the aeration tank. The necessary experiments were carried out in the department of waste water treatment and water ecology. The article includes the scheme of the facility and other parameters of the experiments, which has been carried. The combination of aerobic and anaerobic processes helps to provide proper quality of integrated biological treatment. Chambers of the aeration reactor were also equipped with the polymer feed of various structures. The sludge treatment that was also strongly needed was made by means of aerobic stabilization with the use of ejecting aeration. The results of experiment showed a good effect in both components – sewage and sludge treatment. Afterwards there was also an industrial model launched which confirmed the results of the previous stage

The settling behaviour of an activated sludge with simultaneous nitrification and dentrification

Sedimentation properties of activated sludge from the bioreactor with simultaneous nitrification and denitrification are studied in this paper. MLSS was about 2 g/l in the bioreactor, F/M ratio less than 0.4 gCOD/(gMLSSd), average dissolved oxygen concentrations were 0.35–0.75 mg/l. Latin square design method was used in this experiment. The results show that biomass at SND is characterized by high settling velocity. Sludge settling velocity function for this biomass was obtained

Removal of nitrogen and phosphorous from domestic wastewater

This work is aimed at providing a deep cleaning from nitrogen and phosphorus at the requirements level for a small capacity waste water treatment plants with active sludge. The wastewater treatment technology includes: mechanical screen, anaerobic reactor, anoxic reactor, two aerobic reactors with floating media, aerobic reactor, clarifier, bioreactor, purification, filter, filter of tertiary treatment with the sorbent, ultraviolet disinfection facility. The sludge treatment includes aerobic stabilizer and facility of mechanical dewatering. The developed technology ensures deep purification of household waste waters from nitrogen and phosphorus. The degree of purification in the ammonium-ion reaches of 99.5%. Efficiency of total nitrogen removal (the sum of ammonium, nitrite and nitrate nitrogen) is 85%. The efficiency of biological purification of phosphates is 97.8 percent that is achieved without the use of coagulant. Requirements are met in most cases

Numerical Simulation of Propagation of Plane Turbulent Straitened Jet in Counter Flow Using LES Turbulence Model

AbstractIn technical applications are often used jets, emerging in the counter. Experimental study of such flows for the plane and axisymmetric cases was carried out in [1–5]. In [4] with an approximate integral method and some hypotheses about the nature of the course, based on experimental data obtained approximate analytical expressions for the basic characteristics of axisymmetric flow within the boundary layer for the case of a>>1, where a - geometric parameter characterizing the ratio of the size of the incoming flow and the jet directed toward him. In experimental studies also generally considered the case of large values of a.The following research carried out for the plane case for moderate values of a =10÷25, in which the essential straitness jet. Calculations were carried out on the basis of time-dependent system of Navier-Stokes equations for turbulent flow, implemented using LES turbulence model in the complex ANSYS CFX. On the basis of the conservation laws for an analytical assessment of the range of parameters in which there is a solution to the problem, and compared the results of the numerical solution with the available experimental data