Calculation of the volume of sludge from treatment facilities in the city of Lebedyan (Chertovitsy)

Characteristics of raw and treated waste water

No. p / p Parameter name Initial waste water, mg / dm 3 Purified waste water mg/dm 3
– BOD full
– Suspended solids
– Nitrogen of ammonium salts N(NH4+) 35 (in terms of ammonium ion 44.8) 0.39 *(in terms of ammonium ion 0.5)
– Nitrite nitrogen N(NO 2 ) 0.02 *(in terms of nitrite anion 0.08)
– Nitrate nitrogen N(NO 3 ) 9 *(in terms of nitrate anion 40)
– Phosphate concentration PO 3 4 10*(in terms of phosphorus 3.3) 0.46 *(in terms of phosphorus 0.15)
– Surfactants (surfactants) 8.5 0.5*
– Oil and oil products 0.05*
– Fats normalized by BOD

We determine the volumes of raw sludge for all types of runoff:

1) Determine the amount of dry matter and absolutely dry excess sludge that is retained from the waste liquid in the settling tanks:

where

– concentration of contaminants in wastewater at the outlet of primary sedimentation tanks, mg/l;

– concentration of pollutants in wastewater in terms of suspended solids:

– daily consumption of waste water, m³ / day.

1.1. Economic household:

250-3/10 6 *1000=0.247m 3

1.2. Boiler room:

Suspended solids 220-3/10 6 *1000=0.217m 3

1.3. Dye:

1.4. Glue:

1.5. Total: Q dry = 0.06135 m3/day.

Total: 0.464m 3

2) Determine the amount of dry excess sludge from the secondary settling tanks:

u dry = ;where

– removal of activated sludge from secondary settling tanks;

Pr – Growth of activated sludge in aeration tanks:

,

where -concentration of suspended solids in wastewater entering the aerotanks;

-growth factor ( );

– BOD concentration of wastewater entering the aerotanks, mg/l ;

2.1. Household: Pr u003d 0.8K out + 0.3L en u003d 0.8 * 300 + 0.3 * 725 u003d 457.5 mg;

Pr=0.8K out +0.3L en =0.8*220+0.3*250=176+75=251

u dry u003d 251-10 / 10 6 * 1000m 3 u003d 0.241

2.2. Boiler room: Pr u003d 0.8K out + 0.3L en u003d 0.8 * 190 + 0.3 * 190 u003d 209 mg;

2.3. Paint: Pr u003d 0.8K out + 0.3L en u003d 0.8 * 300 + 0.3 * 780 u003d 474 mg;

2.4. Glue: Pr u003d 0.8K out + 0.3L en u003d 0.8 * 300 + 0.3 * 1020 u003d 546 mg;

2.5. Total: u dry = 0.03631 m3.

Total: u dry = 0.241m 3

5) The total volume of sediment and activated sludge at the outlet of the sludge thickener:

.

, where γ cm is the volumetric weight of the sediment 1.03 t/m³;

(0.464+0.241)*100/(100-98)*1.03=0.36m 3

In cm = 98% – moisture content of the mixture after the vertical sludge thickener.

The calculation is made in accordance with SNiP clause 6.387 … 6.400.

Determine the area of silt pads

F= ; m 2 , where

Q – the amount of sediment after stabilization, m 3 /day;

– coefficient taking into account the load is taken according to SNiP

v. 64 depending on the characteristics of the sediment and the type of silt

sites;

– climate coefficient on the map, hell. 3 SNiP.

Area of one site:

F 1 = ;

NAP – a layer of sediment inlet in summer 0.25 … 0.3 m, in winter 0.5 m.

Number of silt pads:

;

The width of the site is taken depending on the spreading radius (R=20m) with one outlet not > 20 m, with 2 outlets not > 40 m.

Knowing the width of the site, you can determine the length:

;

It is necessary to check whether the obtained area is sufficient, taking into account

freezing sediment in winter

, m

from here

F= m 2 , where

– freezing period (number of days with average daily t < -10 0 С

(Fig. 3 SNiP));

– coefficient taking into account the decrease in the volume of sediment due to

winter filtration and evaporation (25% moisture) = 0.75;

– the freezing height depends on the climatic conditions (for

middle lane u003d 0.5 … 1 m) – climatology;

– part of the area allocated for winter freezing = 0.75.

Additional area occupied by rollers, grooves, etc. is taken into account by the coefficient 1.2…1.4 (respectively for large and small stations).

Disadvantages of using silt pads:

Large areas required.

Bad smell, flies breeding.

Therefore, for large stations, mechanical sludge dehydration is used on vacuum filters, centrifuges, filter presses.

Bibliography.

1. Yakovlev S.V. , Karelin Ya.A., Zhukov A.I., Kolobanov S.K.

“Sewerage”. Textbook for high schools. 1975

2. M. P. Lapitskaya “Waste water treatment. Examples of calculations.” Textbook for high schools. 1981

3. Laskov Yu.V. , Voronov Yu.V., Kalitsun V.I. “Examples of calculation of sewer structures”.

4. SP 32.13330.2012 Updated edition of SNiP 2.04.03-85 “Sewerage. External networks and structures”.

5. Designer’s reference book: “Sewerage of populated areas and industrial enterprises”, second edition, under the general editorship of V.N. Samokhin. M .: Stroyizdat, 1981.-639s.

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