The calculation of the wastewater balance was carried out according to the methodology of the GGI for reservoirs

The equation of water balance, in our case, is described by the following formula:

WОС+WСН+WПР.ПОВ+WПР.ГР+QДР.В=WИСП+WФ+QВДСН+∆W

W ОС - precipitation falling on the surface of lakes during the warm period;

W СН - precipitation falling on the surface of lakes during the cold period;

The average annual precipitation is 300 mm, of which 80% is in the form of liquid precipitation, 20% in the form of snow;

The change in water volume in lakes due to precipitation is determined by multiplying the amount of precipitated precipitation by the area of the storage mirror.

The storage area is 23800 m2:

WOC = (0.3 * 80/100) * 23800 m2 = 5712 m3

W СН = (0.3 * 20/100) * 23800m2 = 1428 m3

Total precipitation - 5712 + 1428 = 7140 m3

WRP.POV - water flow into the reservoir from the surface water catchment. The accumulator-evaporator along the perimeter is dipped, which excludes entry into the of water from the surface watershed.

Therefore, when calculating the water balance, the W RP.WRM is assumed to be 0.

WPR.GR is the inflow of groundwater.

Due to the fact that the reservoir is located on a hill, there is no inflow of groundwater. The main place for unloading groundwater in

This area is the "Mormishnoe" lake located 300 meters to the south of the reservoir. For calculation, the value WPR.GR is assumed to be 0.

QDR.V - the volume of wastewater discharged into the accumulator is:

In the summer period - 100 m3 / day;

In winter - 50 m3 / day.

For calculation, we take an average daily volume of 75 m3 / day.

QDR.B = 75 * 365 = 27375 m3 / year.

The expenditure part of the balance is:

WISP is the volume of water that is removed as a result of evaporation from the water surface of the evaporator storage tank.

The long-term average evaporation rate for a given area is 670 mm, therefore, the volume of evaporating water will be:

WISP = 0.670 * 23800 = 15946 m3 / year.

WF - filtration losses from the accumulator-evaporator.

Calculation of the volume of filtration losses is made by the following formula:

WF = ((K * m * H0) * 365) / (0.366 * (lgR / RK))

K is the filtration coefficient of the aquifer, 0.8 m / day; m - The power of the aquifer is 5.6 m;

H0 - height of the sewage water column in the accumulator 0.25 m

R - Distance from the center to the aquifer supply circuit, m. The distance from the center to the aquifer supply loop is determined

according to the formula:

R = RK + 15 = 87.06 + 15 = 102.06 m

RK is the radius of the accumulator, m;

The radius of the drive is determined by the formula:

RК = √S / π = √23800 / 3,14 = 87,06 365 - number of days per year;

WF = ((0.8 * 5.6 * 0.25) * 365) / (0.366 * (log102.06 / 87.06)) = 408.8 / 0.02527 = 16177.285 m3 / year

The filtration losses from the accumulator will be 16177,285 m3 / year. The hydrogeological characteristics given in the formulas are

data of the geological survey report. Novo-Borovskaya geological survey crew 1960-1964 No. 2766, Volume 1.

QVSN - volume of water taken from the accumulator, m3.

In our case, there is no water from the storage tank. QVDCN = 0.

ΔW is the change in the volume of water in the reservoir, which includes a discrepancy in the water balance, which includes its unaccounted articles.

Substituting in the equation of the water balance the volumes of the input and expenditure parts, we obtain the following amount of change in the volume of water in the storage tank:

The input part - 7140 + 27375 = 34515 m3

The expenditure part - 15946 + 16177.285 = 32123.285 m3 ΔW = 34515 m3 - 32123.285 m3 = 2391.715 m3

To justify these discharge volumes, the water balance of the drive is calculated, according to the Designer's Handbook, the section "Treatment of industrial effluents", Moscow, 1968, according to the following formula:

W = W0 + n (ΣWH - ΣWС), where

Wp - water volume in the accumulator after the n-th accumulation cycle;

W0 is the initial volume of water in the storage tank before putting it into operation,

5950 m3;

N - number of cycles of accumulation in years;

ΣWH - the sum of all water receipts in the accumulator per one cycle in m3 (incoming = 34515 m3)

ΣWС - the sum of all discharges and losses of water from the accumulator per one cycle in m3 (flow rate = 32123,285 m3)

W = 5950 + 5 * (34515 - 32123.285) = 17908.575 m3

The projected volume of water that the accumulator-evaporator can hold is 76,440 m3.

With the planned amount of discharge at the end of the project, the volume of accumulated sewage will be 17,908.575 m3. Consequently, the design volume of the storage device allows discharging wastewater without emergency overflows for 5 years, i.e. period of validity of the VCP project.

Conclusion

The results obtained for industrial wastewater after the treatment using sodium hydroxide and calcium hydroxide combination are in par with the synthetic sample results. The sodium hydroxide and calcium hydroxide combination shows the better removal efficiency with less volume of sludge compared to other precipitating agents.

The ph of the sample and dosage of sodium metabisulphite has a strong effect on the reduction rate of hexavalent chromium. The ph value of 2 and contact time of 5 mins with the dosage of sodium metabisulphite as 80 mg/l were found to be optimum operational parameters for the reduction of hexavalent chromium. The optimum dosage recorded are 100mg/l and 400mg/l of ca(oh)₂ + naoh and fecl₃ respectively. Experiments on industrial wastewater show that, removal efficiency is in par with the efficiency obtained for synthetic sample experiments, except for ferric chloride. The cr(iii) removal efficiency using calcium hydroxide and sodium hydroxide combination was found to be 99.7% and with volume of sludge produced as 7 ml/l.

Wastewater characterization is an important step in designing effective treatment facilities for industrial wastewaters. This is especially true for tanneries which exhibit significant differences in their production processes that generate effluents of unique and complex nature. Characterization is also needed for assessing the performance of individual unit operations and processes. Most pollutants in wastewaters appear to exist either in particulate form or are associated with particulates. This understanding led to the wastewater treatment strategy of removing particulate and colloidal matter in the primary step using suitable coagulants. A study investigated about chemically enhanced primary treatment (cept) technology that uses different coagulants for enhanced pollutants removal at the primary stage of the wastewater treatment. Among those coagulants used, alum has been found to be the suitable coagulant for tannery wastewater in a dose range of 200-240 mg/l as al₂(so₄)³ and it has removed 98.7-99.8% of chromiumhowever other cod content needs secondary treatment for the tannery effluent. Therefore, cept technique offers almost complete removal of chromium and produces an effluent that will no more affect the receiving water bodies [43-45].

Commercial conventional chrome tanning has poor chromium uptake, only about 55-60% (average). So, constant innovative process modifications for cleaner technology have been of the utmost importance in the leather-processing sector to safeguard our environment. The method employed in the leather processing industry subjects the hides and skins to treatment with a wide variety of chemicals and passage through various unit operations. All this involves an enormous amount of time and they contribute to an increase in chromium, cod, chlorides, sulfates and other mineral salts, which end up as effluent. But, perhaps more alarmingly, the process uses profuse quantities of water in areas where there is rapid depletion of ground water. Very provoking research paper was presented by mukherjee, 2006 in the international union of leather technologies and chemist societies (iultcs) congress to overcome this great challenge. This study explored a process to reduce water usage, pickle and basification-free chrome tanning [43-45].

References

1. T. T. Shen, “industrial pollution prevention,” 2^nd edition, springer, pp. 40, 1999.

2. M. M. Altaf, f. Masood, and a. Malik, “impact of long-term application of treated tannery effluents on the emergence of resistance traits in rhizobium sp. Isolated from trifolium alexandrinum,” turkish journal of biology, vol. 32, pp. 1-8, 2008.

3. V. J. Sundar, j. R. Rao, and c. Muralidharan, “cleaner chrome tanning—emerging options,” journal of cleaner production, vol. 10, pp. 69-74, 2002.

4. B. Wionczyk, w. Apostoluk, and w. A. Charewicz, “solvent extraction of chromium (iii) from spent tanning liquors with aliquat 336,” journal of hydrometallurgy, vol. 82, no. 1-2, pp. 83-92, 2006.

5. M. Marchese, a. M. Gagneten, m. J. Parma, and p. J. Pave, “accumulation and elimination of chromium by freshwater species exposed to spiked sediments,” archives of environ contamination and toxicology, springer, vol. 55, no. 1, pp. 603-609, 2008.

6. s. Avudainayagam, m. Megharaj, g. Owens, r. S. Kookana, d. Chittleborough, and r. Naidu, “chemistry of chromium in soils with emphasis on tannery waste sites,” review of environmental contamination and toxicology, springer, newyork, vol. 178, pp. 53-91, 2003.

7. j. C. Akan, e. A moses, and v. O. Ogugbuaja, “assessment of tannery industrial effluent from kano metropolis, nigeria,” asian network for scientific information, journal of applied science, vol. 7, no. 19, pp. 2788-2893, 2007.

8. G. C. Kisku, s. C. Barmanland, and s. K. Bhargava, “contamination of soil and plants with potentially toxic elements irrigated with mixed industrial effluent and its impact on the environment,” journal of water, air, and soil pollution kluwer academic publishers, vol. 120, no. 1-2, pp. 121-137, 1999.

9. R. Aravindhan, b. Madhan, j. R. Rao, b. U. Nair, and t. Ramasami, “bioaccumulation of chromium from tannery wastewater: an approach for chrome recovery and reuse,” environmental science and technology, american chemical society, vol. 38, no. 1, pp. 300-306, 2004.

10. I. Tadesse, s. A. Isoaho, f. B. Green, and j. A. Puhakka, “lime enhanced chromium removal in advanced integrated wastewater pond system, bio resource technology,” elsevier, vol. 97, no. 4, pp. 529-534, 2006.

11. A. Cassano, l. D. Pietra, and e. Drioli, “integrated membrane process for the recovery of chromium salts from tannery effluents,” industrial & engineering chemistry research, american chemical society, washington, dc, vol. 26, no. 21, pp. 6825-6830, 2007.

12. J. Ludvik, “chrome balance in leather processing, regional programme for pollution control in the tanning industry in south-east asia,” united nations industrial development organization report, 2000.

13. M. Ali awan, m. A. Baig, j. Iqbal, m. R. Aslam, and n. Ijaz, “recovery of chromium (iii) from tannery wastewater,” journal of applied sciences and environmental management, bioline international, vol. 7, no. 2, pp. 5-8. 2003.

14. S. M. Nomanbhay and k. Palanisamy, “removal of heavy metal from industrial wastewater using chitosan coated oil palm shell charcoal,” electronic journal of biotechnology, vol. 8, no. 1, 2005.

15. R. M. Jayabalakrishnan and d. Aselvaseelan, “efficiency of mono and mixed columns of vermiculites for treating raw tannery effluent,” journal of applied science, asian network for scientific information, vol. 7, no. 7, pp. 10481052, 2007.

16. U. N. Rai, s. Dwivedi, r. D. Tripathi, o. P. Shukla, and n. K. Singh, “algal biomass: an economical method for removal of chromium from tannery effluent,” bulletin of copyright © 2010 scires jep 58

17. Impacts of chromium from tannery effluent and evaluation of alternative treatment options

18. Environmental contamination and toxicology, nbri research publication, vol. 75, no. 2, pp. 297-303, 2005.

19. S. Haydar and j. A. Aziz, “characterization and treatability studies of tannery wastewater using chemically enhanced primary treatment (cept),” a case study of saddiq

20. Leather works, journal of hazardous materials, elsevier, vol. 173, no. 2-3, pp. 1076-1083, 2007.

21. Yakovlev sv, gubiy ig, pavlinova ii, rodin v.n.

Integrated use of water resources: textbook. Help. - m.: the highest

School, 2005. - 384 p.

22. Alekseev ls, pavlinova ii, ivleva ga the basics of industrial

Water supply and sanitation. - м.: асв, 2013. - 360 with.

23. Adelshin ab, busarev av, selyugin as, urmitova ns,

Muratova n.a. calculation of facilities for the purification of industrial waste

Water. Part 1. Mechanical and chemical treatment of industrial effluents:

Training. Help. - kazan: ksasu, 2010. - 67 with.

24. Alekseev mi, kurganov a.m. organization of leads

Surface (rain and thawed) runoff from urbanized