Project II. Public Utility Minskvodokanal (PU Minskvodokanal)

10.3.  Project II.  Public Utility Minskvodokanal (PU Minskvodokanal)

10.3.1. Project Description

As of January 1, 2002, the population of the City of Minsk was 1712.6 thousand people, including a population of 1627 thousand people (95%) comprising the residential sector, which is connected to the sewage system.  The Minsk wastewater treatment plant, which was put into operation in 1963, treats a mixture of domestic and industrial wastewater generated through the economic activities of the industrial enterprises and the inhabitants of the city.

The development of the production facilities was staged: the first stage – up to 210 thousand m³/day; the second stage – up to 410 thousand m³/day and the third stage – by 800 thousand m³/day.  The exact carrying capacity of the wastewater treatment facilities is 670 thousand m³/day (244.6 mln m³/year).

The existing complex of wastewater treatment facilities has been designed for the complete biological treatment of the wastewater.

The wastewater treatment facilities include:

- Mechanical installations: screen facilities, grit chambers, pre-aerators and pre-settling radial tanks. Drying beds are used for the dehydration of collected sand, vacuum filters and the dehydration of raw sediment.

- Planned production capacity for the mechanical installations: 800 thousand m³/day.

- Installations of biological treatment: four-cell aeration tanks – mixers, final radial settling tanks, concentration tanks, air blowers and dehydration of surplus activated sludge using centrifuges СР 3074.

- Design capacity of biological treatment installations: 670 thousand m³/day.  On average, 20% of the volume of wastewater received by the Mink wastewater treatment plant each day consists of industrial effluents from enterprises.  These wastewaters are mainly from chemical, engineering, light, food and construction material industries.

The actual average daily volume of wastewater received by Minsk wastewater treatment plant is about 750 thousand m³/day; 100 thousand m³/day are discharged to the Svisloch River after only mechanical treatment and 650 thousand m³/day – after complete biological treatment.

Local monitoring of discharge is carried out once every 10 days; internal monitoring takes place two times a day.  Tests are taken in the place of discharge of treated effluent to the Svisloch River as well as in the Svisloch River upstream and downstream of discharge.

The average annual concentration of wastewater coming for treatment is: BOD₅ - 2.13 mg/l, suspended solids - 200 mg/l.  The treated effluent discharged to the Svisloch River contains 13 mg/l and 22 mg/l accordingly.  The concentration of ammonia nitrogen in treated effluent reaches 12 mg/l.

Table 10.5 :  Tests of Wastewater are Subject to Chemical, Biological, Physical – Chemical and Bacteriological Analysis in Conformity with Schedule of Laboratory Control.

The efficiency of the treatment of wastewater from all over the city is as follows:

- BOD₅ - 94%;

- suspended solids -88%;

- ammonia nitrogen - 60%;

- phosphates -60%;

- oil products - 96%;

- synthetic surface active substances - 80%;

- COD - 83%;

- zinc - 87%;

- copper - 72%;

- chromium (total) - 86%;

- nickel - 65%;

- iron - 87%.

In that way the volume of effluent discharge subject to efficiency of treatment is as follows (mln. m³/year):

- effluents treated to standard quality – 244.55 (89.6%);

- insufficiently treated effluents  - 28.36 (10.4%).

At present, the deterioration of the works and equipment of the Minsk wastewater treatment plant has reached from 40 to 90%.

10.3.2. Mitigation Measures

There are no processes for the removal of nitrogen and phosphates from treated effluent.  In order to ensure the necessary treatment efficiency of wastewater being directed to the Minsk wastewater treatment plant it is necessary to complete the construction of the initial wastewater treatment facility complex, which would have a carrying capacity of 100 thousand m³/day. The estimated cost for the implementation of the above-mentioned measures is $US 15 million.

10.3.3. Feasibility Analysis

The economic assessment 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 PU Minskvodokanal, the following input data was used:

- investment into reconstruction and expansion of the treatment facilities (for five years) – $US 15000 thousand.

- operational (current, annual) costs for the newly created facilities – $US 70.0 thousand.

The respective input data are presented in Annexes 1-3 and used in the calculation for Table 10.6.

Table 10.6 : Reduction in Total Mass of Mono-Pollutant to be achieved in Pollution with Effluent from Municipal Treatment Facilities within Five Years

Calculation of mono-polluter (М):

М = ∑ D_i V_i = 30675 c. t.

Calculated per year М₁ = 6135 c. t.

D_a = 275 * 1.75 * 6135 = $US 2952 thousand

Calculation of increment of the lost financial benefit (I):

I is assumed in professional judgment as 10% of D_a

I = $US 295 thousand

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

E_r = D_a + I = 2952 + 295 = $US 3247 thousand

Calculation of the reduced costs (∆C)

∆C = Е * К + Т_c = (0.12 * 15000) + 70 = $US 1870 thousand

Т_c – current operational costs of only reconstructed treatment facilities – $US 70 thousand

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

∆U = E_r - DC = 3247 – 1870 = $US 1377 thousand

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

Т = К / ∆U = 15000/1377 = 10.9 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 10.9 years economically effective and justified.

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