Project III. Mogilev Public Utility Gorvodokanal

10.4. Project III.  Mogilev Public Utility Gorvodokanal

10.4.1. Project Description

The population of the City of Mogilev is 395.5 thousand people, including 341.3 thousand people (94%) comprising the residential sector which is connected to the sewage system.  The municipal treatment facilities processes the industrial and municipal wastewater.  The first stage of the facility was commissioned in 1970.  The industries discharging their effluents to the wastewater treatment facilities include (with various specific weight) the chemical, light, food and engineering sectors.

The wastewater treatment facility complex uses a series of treatment processes and technologies to treat the industrial effluents and sanitary wastewater.  The processes include mechanical treatment, consisting of screens, grit chambers, pre-aerators, primary clarifiers and biological treatment within aeration tanks. Disinfection of the biologically treated effluent is currently not carried out, as the existing chlorination plant is not operational.

Wastewater treatment at the above-mentioned facilities takes place in two treatment lines which have been formed as a result of the commissioning of three treatment facilities in turn.  The treatment lines can work both in general and in detached modes.  Discharge of treated effluent to the Dnipro River from biological ponds (the last unit of treatment chain) is through a dissipating outlet comprising a 9 km long open canal.

The total designed capacity of the wastewater treatment facilities for two treatment lines is 255 thousand m³/day.  The existing capacity is 170-190 thousand m³/day.

The main sources of industrial effluents are the industries which produce man-made fibre (Mogilev “Khimvolokno” and Mogilev artificial fibber plant).  Mostly organic contaminants are discharged to communal sewerage system, in particular: aromatic compounds, hydrogen sulphide, fibres as well as heavy metals (zinc, cobalt, etc.).

Pre-treatment at Mogilev “Khimvolokno” is carried out through biological treatment facilities, which have a planned production capacity of 45000 m³/day.  The Mogilev artificial fibber plant includes facilities for zinc elimination, decontamination, blending and biological ponds.  The planned production capacity of the unit is 44800 m³/day.

Effluents discharged from Mogilev mechanical engineering industries to the communal sewerage system contain zinc, nickel, copper, chromium and oil products.  Industrial effluents comprise 49.7% of the total volume of the municipal wastewater. 

The efficiency of decontamination as indicated by the main indices is as follows:

- BOD₅   - 98 %;

- Suspended solids – 94.9%.

Monitoring of discharge is carried out at regular intervals in several points: from the canal after biological ponds (once a week) and from the canal at the point of discharge (once a month).  Sampling is carried out at the canal at the outlet from the biological ponds, from the canal at the point of discharge and from the Dnipro River 500 meters upstream and downstream of the point of discharge.  The laboratory uses a “mean-shift” type of sampling protocol (i.e., during a shift the sampling is carried out every two hours and then the average index is derived).  Monitoring of the biologically treated effluent discharge rate is carried out at the Porshal chute and in proportional weir prior to the contact reservoirs.

According to Mogilev Municipal Inspection of Natural Resources and Environmental Protection, the annual average of contaminants content in treated effluent in the canal after biological ponds are as follows:

Table 10.7 : Qualitative Characteristics of Treated Effluent discharged from the Wastewater Treatment Facilities of the Town of Mogilev

The main drawbacks of the existing wastewater treatment facilities are as follows:

- Lack of treatment facilities for nitrogen and phosphorus;

- Lack of equipment for retaining fibres which are constantly present in the effluents;

- Problems with the air blower in the aeration tanks;

- Lack of equipment for monitoring the quality of incoming wastewater;

- Lack of processes to mix the coming discharge;

- Inadequate number of final settling tanks and installations for treatment of effluents from heavy metals.

Moreover, the wastewater treatment facilities require major repairs, the pump installation should be replaced and the laboratory should be equipped with more modern equipment for monitoring incoming wastewater and outgoing treated effluent.

All the above mentioned and some other issues could be addressed through the construction of a fourth wastewater treatment facility (with a capacity is 100 thousand m³/day) and reconstruction of the existing facilities. The following is scheduled: replacement of screen facilities, modernization of primary clarifiers, reconstruction of beds for drying collected sand, replacement of air blower system with an up-to-date system and reconstruction of secondary clarifiers. However –the shortage of financial resources allocated from local and central sources of financing represents a serious obstacle to the implementation of the project.  The planned production capacity of the first starting complex within the project is 25 thousand m³/day. It includes: construction of an inlet distributing chamber, replacement of the missing secondary clarifiers, construction of a new sludge circulating station, installation of SAW-ozone technology for the treatment of discharges and provision of a production control system to ensure the quality of the discharge. Construction of the first initial complex is scheduled for completion in 2005, but currently the allocated financial resources are insufficient for this task.

10.4.2. Mitigation Measures

To reduce the pollution level of the supplied wastewater, the environmental measures are required as presented in Table 10.8.

Table 10.8 : Environmental/Mitigation Measures for Mogilev Gorvodokanal for 5 years

10.4.3. 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 Mogilev Gorvodokanal, the following input data was used:

Investment required for reconstruction and expansion of the treatment facilities – $US6282.27 thousand.

Operational (current) costs – $US 32.0 thousand

The respective input data are presented in Annexes 1-3 and used in the calculations for Table 10.9.

Calculation of mono-pollutant (М):

М = ∑ D_i V_i = 11810 c. t.

Calculated per year М₁ = 2362 c. t.

D_a = 275 * 1.75 * 2362 = $US 1136 thousand

Calculation of increment of lost financial benefit (I)

I is assumed in professional judgment as 10% of D_a

I = $US 113.6 thousand

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

E_r = D_a + I = 1136 + 114 = $US 1250 thousand

Calculation of the reduced costs (∆C)

∆C = Е * К + Т_c = (0.12*6282.3)+32 = $US 785.9 thousand

Where, Т_с – current (annual) operational costs of newly commissioned wastewater treatment facilities – $US 32 thousand.

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

∆U = E_r - ∆C = 1250-786 = $US 464 thousand

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

Т = К / ∆U = 6282/464 = 13.5 years

Based on the 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 13.5 years is economically effective and justified.

Table 10.9 : Reduction in Total Mass of Mono-Pollutant to be Achieved in Pollution with Effluent from Municipal Treatment Facilities within Five Years

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