PL154994B1 - Biological sewage treatment process - Google Patents

Description

RZECZPOSPOLITA PATENT DESCRIPTION 154 994

POLAND

OFFICE

PATENT

RP

Additional patent to patent no. - Filed: 87 07 30 (P. 267080)

Precedence - Int. Cl. ⁵ C02F 3/12

Application announced: 88 03 31

Patent description published: 1992 03 31

Creators of the invention: Ryszard Przybyłowicz, Lech Narbutt

The holder of the patent: Przedsiębiorstwo Eksportu Budownictwa "INSTALEXPORT", Warsaw (Poland)

Method of biological wastewater treatment

The subject of the invention is a method of biological wastewater treatment with the activated sludge method carried out in several phases and several interconnected reactors.

The method of biological wastewater treatment is known from the Polish patent specification No. 133 176. This method consists in the fact that the biological treatment process is carried out in at least two reactors, the first of which is adapted to a continuous inflow of wastewater under the conditions of constant oxygen content and continuous mixing thereof with active sludge, while the next reactor is adapted to periodic outflow of sewage under changing oxygen conditions from oxygen deficit to the maximum oxygen concentration.

There is also a known method of biological wastewater treatment from the Polish patent specification No. 121 946. This method consists in the fact that the treatment process is carried out in two phases. In the first, the wastewater is loaded with active sludge in the amount of 2 kg BODs per kilogram of dry mass and 24 hours, with a part of the excess sludge being removed to lead to respiration of the substrate. Then, in the second phase of activation, the wastewater is treated with an active sludge in the amount of 0.15 kg BOD5 per kilogram of dry matter and 24 hours, with the separation of the biocenoses of the first and second phases.

The essence of the invention is a method of biological wastewater treatment in which the treatment process is carried out in at least two phases which take place in at least two biological reactors. A mass of microorganisms is introduced into the circulation cycle against the direction of the treated sewage flow, and oxygen is introduced into the sewage by means of oxygenation devices. During the process of wastewater treatment, different conditions of oxygen concentration occur in individual phases, as well as different residence times of microorganisms in contact with the sewage. Two purification phases take place in one complete cycle of the circulation of the mass of microorganisms with time T closed in two reactors. One phase of oxidation at time Tn takes place in the oxidation reactor in which there is a constant oxygen concentration greater than one, most preferably equal to Cn - 2.5 g O 2 / m ³ , from which the treated sewage flows out. The second reduction-oxidation phase of Tro duration is carried out in the reduction-oxidation reactor and consists of two periods. In first

In the period of time Tr, the oxygen concentration is kept at a level close to zero Cr-Og0 ₂ / in ³ . In the second period of time To, the oxygen concentration is kept above zero, most preferably Co = 0.5 g O2 / m3. Raw sewage flows into this reactor along with a mass of microorganisms. The ratio of the duration of the reduction-oxidation phase Tro to the duration of the oxidative phase Tn is in the range

T.

1.5> _ ^T _> 0.5.

Tn

On the other hand, the ratio of the duration of the first period Tr to the duration of the second period To in the reduction-oxidation phase is in the range

1.8> _L · -> 0.2.

This

The average time T expressed in hours of displacement of microorganisms with mass M in kilograms in the reactor system in which the process of the reduction-oxidation phase Rro and the oxidation phase Rn is carried out at the flow of raw sewage with the capacity Qh in m3 / h is determined by the equation _{T =} M (Xr -Xro)

Qh · · Xr XRO XRO is where the concentration of microorganisms in the reactor RRO expressed in kg / m ^3, and Xr is the concentration of microorganisms in recyrkulacie expressed in kg / m3.

The biological wastewater treatment process carried out according to the invention enables energy savings to be achieved by reducing oxygen consumption and increasing the biodegradation of pollutants. This process also secures the conditions for biological reduction of biogenic compounds, especially nitrogen, which extends the scope of sewage neutralization with cleaning elements necessary for water renewal processes.

The subject of the invention is presented in the following embodiment. Municipal wastewater treatment plants with the capacity of the daily Qd = 2Οθ0θ m ³ / cr and hourly Qh - 1,000 m3 / h, ^I n ^{and k} oncentracj BOD ^{5 - 0.15 kg} / m ^{3 of} nitrogen ^{shave g} o ne ^N = ^0.03 kg / m ^{3 dl} and ^he concluded reg suc ^h ^ e ^j weight of the sludge in the reactors was determined in an amount of 20250 kg m = the concentration of suspended solids in the reactor XRO - 3.5 kg / m3 and the concentration of suspended solids in recyrkulacie Xr - 8 kg / m3 carried out attestation tests to obtain the required reduction of BODs = 92% and total nitrogen N - 60% should meet the following conditions

Tro

Tn = 0.5 and

2Ł = i.

Tr

For these conditions, the purification process parameters are as follows:

1) The time of the full cycle T in hours for the movement of microorganisms in the Rro and Rn reactors will be

T = M (Xr-Xro) = 20,250 (8-3.5) _{= 3}

Qh-XR-XR0 1000-8-3.5

2) The duration of the reduction-oxidative and oxidative phases is, respectively, Tro = 1.06h and Tn = 2.12h.

3) The duration of the first and second periods in the reduction-oxidation phase is To = Tr = 0.53 h.

154 994 3

4) The mass of microorganisms M in kg is distributed among the individual reactors in proportion to the duration of the phases according to the calculation:

Mr ₀ = ^{, T} ? ° ' ^M. = ^ ^06-2025 . ° .. "= 6,750k ^g

T 3.18

M _n = ^Tn ' ^M = 232-20250 _ _ 13 500 k ^g

T 3.18

Raw sewage and recirculated activated sludge flow into the Rro reactor, and their mixture is subjected to the purification process in the reduction-oxidation phase consisting of two periods.

In the first period, Tr = 0.53 h, with the oxygenation devices switched off, the oxygen concentration is close to zero. However, in the second period To = 0.53 h, the oxygen supply by oxygenating devices is dimensioned to obtain an oxygen concentration of Co = 0.5 g O 2 / m ³ . In the Rn reactor, the mixture of wastewater and activated sludge introduced from the Rro reactor is subjected to a process in the oxidation phase in which the oxygenating devices are dimensioned to secure the oxygen concentration of Cn = 2.5 g 02 / m ³ . Treated sewage and recirculated sludge are discharged from this reactor.

Claims (2)

Patent claims 1. The method of biological wastewater treatment with active sludge, whereby the sewage is treated in at least two phases carried out in separate biological reactors containing sludge of the same biocenosis, between which the internal circulation of microorganisms is maintained, characterized in that for one complete cycle of time T the displacement of microorganisms in the reactors consists of the time of stay of microorganisms in the reduction-oxidation phase Tro characterized by the time-varying oxygen concentration divided into two periods, the first period of Tr duration, in which the oxygen concentration is kept at a level close to zero Cr ~ 0 g 02 / m ³ and a second period of duration To, in which the oxygen concentration is kept above zero, preferably Co = 0.5 g O 2 / m ³ , the phase of which is the Rro reactor, which receives raw sewage and recirculated mass microorganisms and the residence time of microorganisms in the oxidation phase Tn characterize with a constant oxygen concentration Cn> 1.0 g O 2 / m ^3, preferably Cn - 2.5 g O 2 / m ³ , to which phase the reactor Rn is subordinated. the departure effluent and recycled mass of microorganisms, wherein the ratio of the duration of the phase reduction-oxidation Tro to the duration of the phase oxidative Tn a cycle time of T determines the relationship ^l, 5S> ^2l £ _> 05 Tn while the ratio of the duration of the first period Tr the duration of the second period To in the reduction-oxidative phase Tro determines the relationship This 2. The method according to p. 1, characterized in that the average time T in hours displacement microorganisms weight M kg in the reactor system RRO and Rn at a flow rate of water treated with a capacity Qh m ³ / h is determined equation M (Xr-Xro) QX ^r -X ^ro 'where Xro is the concentration of microorganisms in the Rro reactor expressed in kg / m ³ and Xr is the concentration of microorganisms in the recirculation expressed in kg / m ³ . Department of Publishing of the UP RP. Circulation 100 copies Price: PLN 3,000