Project V. Public Company Mozyr Refinery, Treatment Facilities

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10.6. Project V.  Public Company Mozyr Refinery, Treatment Facilities

10.6.1. Project Description

As of January 1, 2001, the population of the City of Mozyr was 108 thousand people and the population of the Town of Kalinkovichy was 42 thousand people.  The population of the residential sector, which is connected to the sewage system, is 120 thousand people (80%).

The wastewater treatment facilities of the town of Mozyr are a structural unit of the Mozyr Refinery and have been in operation since 1974.  The planned production capacity of this complex is 80 thousand m³/day.

The wastewater treatment facility complex includes the following main technological lines:

- Combined two-stage biological treatment and post- treatment (polishing) of the industrial and sanitary wastewater in biological ponds of Mozyr Refinery;

- One-stage biological treatment of the stormwater runoff and sanitary wastewaters of the towns of Mozyr and Kalinkovichy.

Currently, the total volume of wastewater processed by the wastewater treatment facilities is 58 thousand mі/day which is 72.5% of the potential carrying capacity of this complex.  During June 2002, the wastewater treatment facilities of Mozyr refinery processed 1271664m³ of residential wastewater and 515300м³ of industrial and storm water.

The volume of industrial effluents of Systems I and II, delivered to the mixer for the two-stage treatment is measured by a “Safir” type flowmeter.  The volume of

sanitary wastewaters is measured in a Venturi flume, which is located in front of the mixer for the two-stage treatment process.

After treatment, the treated effluent is discharge through two pipes:

- Pipe No. 1 (manifold of the refinery) – the treated effluent of the Mozyr refinery (the volume of discharge is 26.0 thousand m³/day);

- Pipe No. 2 (former manifold of the nutrient yeast plant) – treated effluent of the towns of Mozyr and Kalinkovichy (the volume of discharge is 32.0 thousand m³/day).

The actual (annual average for 2001 and March 2002) data reflecting the efficiency of the treatment of the Mozyr refinery effluents are given in the following tables:

Table 10.15 : Composition of Effluents of Mozyr Refinery Treated to Standard Quality

Table 10.16 : Average Monthly Results of the Analysis of Effluent from Tail Drain of Mozyr Refinery No. 1 for March 2002

 

Table 10.17 : Average Monthly Results of the Analysis of Effluent from Tail Drain of Mozyr Refinery No. 2 for March 2002

 

The technological process at wastewater treatment facilities provides for treatment of three technological flows of wastewater:

System I: It is designed for the treatment of industrial and storm water runoff, polluted by oil products (up to 2500 mg/l), suspended solids (up to 100-130 mg/l), pH up to 9.0, organic impurity (as for BOD₅ – up to 100-160 mg/l; BOD₂₀ up to 200-260 mg/l; COD up to 250 - 500 mg/l) and phosphates (P) up to 0.5 mg/l.

System II: This system is designed for the treatment of emulsified chemically contaminated wastewaters, containing oil products (up to 5000 mg/l), organic pollutants (as for BOD₅ - up to 150-200 mg/l; BOD compl.- up to 200-300 mg/l; COD - up to 400-600 mg/l), suspended solids (up to 200 mg/l), non-organic substances (chlorides - 300-400 mg/l, sulfates - up to 150 mg/l, sulfides – up to 100 mg/l, ammonia nitrogen (N) – up to 30 mg/l, phosphates (P) – up to 0.5 mg/l) and having a pH about 9.0.

System III: Designed for the treatment of sanitary wastewater from the refinery, industrial enterprises as well as municipal discharges from Mozyr and Kalinkovichy.

The wastewaters of System I undergo mechanical treatment, which includes:

- screen facilities – 2 pieces (D = 6m, q = 193 l/sec);

- oil removers – 4 sections (L = 33 m, В=5.88 m, Нw= 2 m);

- settling tanks – 2 pieces (total useful capacity is 4380m³);

- flotators – 4 pieces (q = 300m³/h).

Afterwards, the wastewater from the flotators of System I is delivered to the mixer which is located in front of the complex of 2-stage biological treatment chamber.  The preliminary treated industrial effluents from System II (about 7000 m³/day) and a part of the sanitary wastewater volume (about 10000 m³/day) are delivered to the same chamber.

The two-stage biological treatment facility complex for the industrial effluents of the Mozyr Refinery includes the following installations:

- aeration tanks: 1 stage (2 sections of the three-corridor aeration tank L*B*Нр = 42*6*5m, V_сумм = 7560 m³);

- final settling tanks – 2 pieces. (D=24m; the cumulative volume of precipitation zones is 2800m³);

- aeration tanks of the 2 stage (4 sections of the three-corridor aeration tank L*B*Нр = 42*6*5m, V_сумм= 15120 m³);

- tertiary settling tanks – 4 pieces (D=24m, the cumulative volume of precipitation zones is 5600m³).

After the two-stage biological treatment process, the wastewaters from System I are directed to the co-ordinated biological ponds for post-treatment through natural airing (two cascading ponds ( a three and a four-step pond), which work simultaneously and which in total process 350 thousand m³/day and. 

The wastewater from System II (about 7000 m³/day which is approximately 30% of the total discharge from the Mozyr Refinery) is treated through mechanical treatment using a similar wastewater treatment scheme as System I.  The wastewater treatment facilities include:

- screen facilities – 2 pieces (D = 6m, q = 193 l/sec);

- oil removers – 4 sections (L = 33 m, В=5.88 m, Нp= 2 m., total useful capacity of precipitation zones is 1584 m³);

- settling tanks – 2 pieces (D = 30 m, total useful capacity is 4380m³);

- flotators – 4 pieces (D = 9 m, total useful capacity is 380m³).

After the flotators, the wastewater from System II is delivered to the mixing chamber of the two-stage biological treatment process.

Pressure pipes are used to deliver the municipal wastewater from the towns of Mozyr and Kalinkovichy and the sanitary discharges from the refinery and industrial enterprises; a total volume of 42000 m³/day arrive at the inlet chamber for technological treatment.

The technological line includes the following:

- screen facilities – 4 pieces. (D = 6 m);

- primary clarifier radial tanks – 4 pieces (D = 24 m, total useful capacity is 5600m³);

- aeration tanks – 2 sections of the three-corridor aeration tank (L*B*Нр = 6*60*5m, V_сум = 1080 m³);

- final radial settling tanks – 4 pieces (D = 24 m, total useful capacity is 5600m³).

After biological treatment (one-stage), the sanitary wastewaters are discharged through Pipe No.2 to the Pripyat River.

Laboratory control of the effluent quality is carried out for the following parameters:

- pH value

- ammonia nitrogen

- nitrate nitrogen

- nitrite nitrogen

- oil products

- sulfates

- chlorides

- phosphates

- dissolved solids

- suspended solids

- biological oxygen demand (BOD)

- chemical oxygen demand (COD)

- phenols

- dissolved oxygen

- sulfides

- copper

- chromium

- nickel

- zinc

- iron

- synthetic surface active substances.

Effluent discharge to the Pripyat River takes place continuously.  Monitoring of the discharge is carried out at regular intervals.

 

Table 10.18 : Composition of Surface Water of the Pripyat River (Average data for 2001)

 

Table 10.19 : Composition of Surface Water of the Pripyat River (Average data for 2001)

Table 10.20 : Results of Analysis of Water of the Pripyat River for March 2002

It is necessary to completely reconstruct the second oil-recovery system (installing US-manufactured oil-water separators and decommissioning the current obsolete concrete oil removers).  The proposed oil-water separators treat oily wastewaters using a pack of coalescing polypropylene nozzles with a patented configuration.  Such separators can ensure effective treatment of the wastewater from free oil products up to 15 mg/l.

The estimated cost for implementation is $US 450-500.  Currently, the design work has been completed, and the building and assembly works have been commenced.

It is necessary to start using ultraviolet disinfection. Application of ultraviolet disinfection method at wastewater treatment facilities instead of the traditional water chlorination will:

- avoid creating conditions that form chloro-organic compounds and chloramines in effluent, which are toxic to fish and all  other members of the aquatic community and accordingly, improve the ecological conditions of the receiving water body;

- avoid active chlorine in the effluent composition;

- exclude the chlorination unit from the wastewater treatment facilities as an environmentally and operationally dangerous production unit;

The estimated cost for implementation is 700-750 thousand $US.  Currently, the design work has been completed, the building and assembly works have been commenced and 2 installations have been purchased.

The sediment dehydration section needs to be reconstructed.  It is proposed to that a filter-press be installed in addition to the existing centrifuges (OGSH) to enable desired dehydration of the sediments.

10.6.2. Mitigation Measures

Improvement of the treatment system for the effluent discharged into Dnipro, and reduction in the pollution level in the Dnipro Basin require:

1.   Complete reconstruction of the second oil-recovery system (i.e., replace the existing obsolete concrete oil removers with the US manufactured oil-water separators).  The operation of the oil-water separators is based on the treatment of oil-containing effluents with a package of coalescing polypropylene nozzles with a patented configuration.  The separators can ensure that the effluent is free from oil products up to 15 mg/l.

2.   Commissioning of the UV-disinfection complex.  The treatment plants using the UV-disinfection method rather than traditional chlorination will allow:

-    eliminate conditions in effluent conducive to the formation of chloro-organic compounds and chloramines, which are toxic to fish and the whole biocenosis in the recipient water body, as well as substantially improving the ecological condition of the water body;

-    eliminate activated chlorine from effluent;

-    exclude the existing chlorination unit from the treatment facilities, as dangerous for environment and operation.

Table 10.21 : Environmental Measures for Mozyr Refinery Treatment Facilities for 5 years

 

10.6.3. Feasibility Analysis

The feasibility analysis of the water-protective measures was carried out by comparing the economic results of these measures with the costs required for their realization.

For the Mozyr Refinery Treatment Facilities, the following input data were used:

- Investment required for reconstruction and expansion of the wastewater treatment facilities – $US 1400 thousand

- Operational current (annual) costs of the newly commissioned wastewater treatment facilities – $US 10 thousand

The respective input data are presented in Annexes 1-3 and used in the calculations in Table 10.22.

Calculation of mono-pollutant (М):

М = ∑ D_i V_i = 2720 c. t.

Calculated per year М₁ = 544 c. t.

Economic estimate of the averted ecological damage for the Dnipro Basin waters (D_a):

D_a = 275 * 1.75 * 544 = $US 262 thousand

Calculation of increment of lost financial benefit (I)

I is assumed in professional judgment as 10% of D_a

I = $US 26 thousand

Calculation of the economic result of the water-protective measures (E_r):

E_r = D_a + I = 262 + 26 = $US 288 thousand

Calculation of the reduced costs (∆C)

∆C = Е * К + Т_c = (0.12  * 1400) + 10 = $US 178 thousand

Calculation of the net annualized economic effect (∆U):

∆U = E_r - DC = 288 - 178 = $US 110 thousand

The payback period (Т) for the investment into water-protective measures is:

Т = К / ∆U = 1400/110 = 12.7 years

Based on environmental design practices, the threshold of effective return for investments into wastewater treatment facilities is 14 years.  Therefore, the suggested project with the estimated payback period of 12.7 years is economically effective and justified.

Table 10.22 : Reduction in Total Mass of Mono-Pollutant to be Achieved in Pollution with Effluent from Municipal Treatment Facilities within Five Years