Project 4. Hot Spot - Municipal Unitary Enterprise “Kursk Vodokanal”

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10.5. Project 4. Hot Spot - Municipal Unitary Enterprise “Kursk Vodokanal”

10.5.1. Description of the facility

Municipal wastewater treatment facilities were put into operation in 1980.  The capacity of wastewater treatment facilities is 54750 thousand m³/year.

Population of the City of Kursk as of 1.01.2001 was                441 thousand people

Those connected to the sewage system as of         2000                323 thousand people

As calculated for               2005                369 thousand people

                                  2015                444 thousand people

 

The total discharge of wastewater by population, as assumed for the calculation, is

                                                2000                26682 thousand m³/year

                                                2005                44530 thousand m³/year

                                                2015                56575 thousand m³/year

Industrial wastewater:                 2000                10220 thousand m³/year

                                                2005                54750 thousand m³/year

                                                2015                62050 thousand m³/year

Storm runoff        :                      2000                10200 thousand m³/year

                                                2005                10476 thousand m³/year

                                                2015                11461 thousand m³/year

 

Characteristics of municipal wastewater treatment facilities

The volume of wastewater received for treatment is 36902 thousand m³/year

Capacity of treatment facilities is 54750 thousand m³/year

The types of treatment are mechanical and biological.

 

Composition of the treatment facilities

Building of Screen Facilities

Three screen (type РМУ-5Б) have been installed for the purpose of screening out large pieces of wastes arriving with the wastewater at the wastewater treatment facilities.

Wastes removed from the screens are collected in metal containers, which sprinkled with chloride of lime and removed to the dump.

Grit Chambers

The wastewater treatment facilities include three horizontal grit chambers with straight-through flow of water.

The sediment caught in the grit chambers is raked up and then delivered with the help of hydraulic elevators through the sludge line to the dehydration beds.

Primary Clarifiers

There are three radial sewage tanks which are 40 metres in diameter with remote collection chutes.  Fresh sediment from the settling tanks is removed in series using rotary pumps.

Aeration Tank-Mixers

Wastewater treatment facilities include four corridor aaeration tank-mixers.  The capacity of each aaeration tank is 22460 m³.

The aeration tanks work through regeneration, using 2 parts.

The content of the dissolved oxygen in every point of the aeration tank varies from 2 to 3 mg/l.

Final Settling Tanks

There are four radial settling tanks, which are 40 metres in diameter, each with remote collection chutes and which are in constant operation.  For settling in the final settling tanks, the activated sludge is drawn to sludge chambers using sludge pumps.

Concentration Tank

There is one radial concentration tank, which is 40 metres in diameter and which is in operation.

Metatanks

There are three metatanks, with each being 17.5 metres in diameter.

Contact Canals

Chlorination of treated wastewater takes place in contact canal consisting of six corridors.

Sludge Drying Beds

There are 59 sludge sheets of cascade type, 4 sheets in each cascade.  Unloading of sediment takes place on two upper sheets of cascade.

Beds for Drying Sands

There are two sand grounds used for dehydration of sediment from grit chambers.

Chlorination Plant

Disinfection of the wastewater is carried out in chlorination plant with application of chlorine gas.  There are six devices “LONEE-100” for this purpose.

The capacity of the chlorination plant is 100 kg of chlorine per hour; it is combined with 42 tonnes of retail stock of chlorine.

Air Blower Installation and Sludge Pumping Station

There are four air blower installations ТВ-300-1.6 with the capacity of 18000 m³/hour each in the engine room of the blowing house (three in operation and one reserve unit).

Operation Flow

Wastewater, which is conveyed to the treatment facilities through the discharge pipe, flows consecutively through the inlet chamber, screen facilities, grit chambers, primary clarifiers and contact canals.

The inlet chamber provides for dropping of the height.  The screen retains large debris in the wastewater.  The grit chambers provide for settlement of heavy dirt, which upon accumulation, is removed by hydraulic elevator to the dehydration grounds.

The effluents from the grit chambers flow into the primary clarifiers, where coarse non-soluble organic dirt is settled, and then is pumped to meta-tanks for further treatment.

The effluents, having passed through the settling tanks, are directed to the aeration tanks for mineralization of organic substances.  The sludge mixture from the aeration tanks is directed to the final settling tanks, where the activated sludge is separated from the cleared liquid.  The sludge that has settled on the bottom is pumped to the sludge chambers and then the circulatory activated sludge is supplied to the aeration tanks, and the excess activated sludge is pumped to the sludge concentration tank, and then to the meta-tanks for anaerobic process.

A part of the excess sludge is supplied to the grit chambers canal for bio-coagulation in order to improve the efficiency of the primary clarifiers. 

The wastewater, after being treated in the final settling tanks, is directed to the contact canals and further discharged to the Seim River through two pipelines.

There is also the option of effluent discharge to the open pit, which can function as a buffer pond prior the discharge to the Seim River.

The digested sludge from the meta-tanks is pumped to the sludge grounds.  The generated gas, methane, is supplied to the gas kiosk and further to the local heating plant.

Analysis of Functioning of Wastewater Treatment Facilities

The screen facilities are operated inefficiently.  The length of their plates is about 4 m, but they are rigid, which has led to their deformation and has resulted in openings between the plates from 0 to 50 mm.  This has contributed to:

- large debris passing through to subsequent facilities;

- skewing of rakes and parting of the master cables.

The grit chambers are characterized by persistent loading of the hydraulic elevator nozzle and excessive depreciation of the scrapers.

The technical condition of the settling ponds is inadequate.  In many sites, the comb spill ways have collapsed, worn out and require replacement of the distributive cover.

The performance of the aeration tanks is inefficient: there are many collapsed aeration tanks, and the air leaders at the ends of the aeration system are literally out of use.  The results of the analysis show that the alkalinity for all tests has indices below the admissible level, while the concentration of volatile fatty acids exceeds the required values.  The situation in the majority of the technological lines of treatment facilities is not better.    

The content of ammonia nitrogen, sulphides, iron, chromium trivalent, zinc, oil products, sulphates and sometimes BOD₅ in incoming wastewater arriving at the wastewater treatment facilities exceeds the maximum allowable concentration; this provides evidence of non-observance of commitments taken by industrial enterprises in relation to the standards of discharge of the industrial effluents to the sewerage system.

Volley discharges of wastewater from the tannery to wastewater treatment facilities with the presence of large quantity of hair and fats still exist.

Unloading pre-dried sediment from the sludge drying beds is effectively not carried out.

Some industrial premises are equipped with obsolete equipment (grit chambers, and primary clarifiers).

There are engineering design flaws (primary clarifiers, aerators in aeration tanks).

Technologically effective concentration tanks should ensure the moisture of the packed sludge at a level of 96.5 – 97.5% within 9-11 hours.  A functioning concentration tank should ensure compaction of the sludge within 15-16 hours.

The station laboratory carries out analysis of the metatanks operation.  The analysis includes determination of alkalinity, volatile fatty acids, nitrogen, ammonia salts, pH, moisture, and the range of initial and digested sediment.  The results of the analysis show that alkalinity in all tests has indices which are below the admissible level and the concentration of volatile fatty acids exceeds the allowable values that are admissible.

At the output, the main indices exceed maximum allowable concentration many times, in particular: BOD_compl from 17 to 114 mg/l, suspended solids – from 9 to 157 mg/l above permissible level and other indices.

All the above mentioned provides evidence of the need for reconstruction of most of the units of the wastewater treatment facilities of the Kursk Vodokanal, including:  the grit chambers, chute, screen facilities building, primary clarifiers and final settling tanks, pumping station of after-treatment, filters building, decantation unit, control reservoirs, sludge grounds and other structures.  The required cost for upgrading and expansion of the Kursk treatment facilities is 380 million roubles in prices of 2001.

10.5.2. Description of Mitigation Measures

Wastewater treatment facilities are designed to ensure complete biological purification of wastewater in aeration tanks and reduction of the concentration of suspended solids and BOD_compl up to 15 mg/l.  Besides subsequent post-purification of the sewerage water with the help of wireframe-filling filters should ensure concentration of the contamination of purified water with suspended solids at the level of 30 mg/l and BOD_compl - 30 mg/l.

10.5.3. Investment Requirements

According to the project financial assets, reconstruction of the Kursk vodokanal would require 380 mln. roubles (for 15 years period), with 340 mln. roubles being applied to increasing the productive capacity of the wastewater treatment facilities from 150 to 300 thousand m³/day.

During the first five years reconstruction of functioning wastewater treatment facilities will require 40 mln. roubles.

10.5.4. Feasibility Analysis and Recommendations

Calculation of the annual damage caused by the inefficient treatment facilities is as follows.

The concentration of polluting effluents, discharged to the treatment facilities, is extremely high (see Annex 3, Table 4.1).  With wastewater, the treatment facilities receive annually over 50 thousand tonnes of polluting ingredients, as estimated by mono-pollutant.  The damage caused by this wastewater could have exceeded 600 million roubles per year.

The treatment facilities retain over 85% of the discharged pollution.  The balance is introduced to the Dnipro, causing substantial harm to the environment.

The estimated characteristics of the wastewater on various stages of treatment in 2005 and 2015 are presented in Table G-8 of Annex. G.

Table 10.12 : Annual Damage caused by Inefficient Treatment Facilities

 

D_a = 1.8 * 8400 * 3848 = 58181.7 thousand roubles

The cost of averted damage caused by pollution of the water body (D_a), including the increment of the earlier loss of profit (I) is accepted as an economic result of the water-protective measures (E_r), by formula:

E_r = D_a + I

 

Calculation of cost of averted damage

D_a = B * β * M,

where B = 8400

β = 1.8

M – reduced mass of the annual volume of pollutants.

 

М = _i * V_i,

D_i – indicator of the relative hazard of discharge into water bodies of a specific (i) pollutant, equal to the reciprocal of MAC.

V_it – volume of discharge of pollutant i for year t.

Σ = 1.8 * 8400 * 2616 = 39554 thousand roubles

 

Calculated per year, the averted damage is 7911 thousand roubles.

 

The economic result of the water-protective measures, including the lost economic benefit, is:

E_r = D_a + I = 7911 + 791 = 8702 thousand roubles

 

The net economic effect of (E_n) of the water-protective measures is calculated as the difference between the annual economic result of the water-protective measures (E_r) and the reduced costs (ΔC).

Table 10.13 : Suggested Damage to be Averted by Year 5 of the Calculation Period

 

E_n = E_r – ΔC

ΔC = e K + T_c,

where K – investment in environmental measures,

T_c – annual operation costs (250 thousand roubles)

e – coefficient of economic effectiveness.

Based on an investment in reconstruction of 380 million roubles (within 15 years), as designed by the Kursk vodokanal project, about 340 million roubles of this amount will be used for capacity upgrading of the treatment facilities from 150 to 300 thousand m³/day.

The first five years of reconstruction of operating treatment facilities will require about 40 million roubles.

ΔC = 0.12 * 40000 + 105.4 = 5854 thousand roubles,

i.e., reduced costs ΔC = 5854 thousand roubles / year.

Averted damage – 8702 thousand roubles / year.

Thus, the net annualized economic effect ΔU makes up:

ΔU = 8702 – 5854 = 2848 thousand roubles.

T = K / ΔU = 40000 / 2848 = 14.0

 

The payback period is about 11 years subject to the efficiency threshold of 13-14 years.

It is advisable to consider the issue of reconstruction of the wastewater treatment facilities separately, not in connection with additional large capital investments (340000 thousand roubles) estimated for the construction of new wastewater treatment facilities.

The current capacity of wastewater treatment facilities is 54750 thousand m³/year with the volume of wastewater being 40000 thousand m³/year.

Taking into account the reconstruction of the operating treatment facilities, the facilities would actually reach a level of treatment that meets the established norms of MAC.