Dissipation in the atmospheric surface layer with a passive tracer concentration, mg per m³, described by unsteady turbulent diffusion equation:

                                                                                          (1)

there is vector velocity, m per sec; w_s is sedimentation rate impurities: for light inert gas impurities w_s=0 m per sec; for heavy w_s = 0,001 m per sec; for aerosols w_s = 0,008 m per sec [2]; k_хуz is coefficient of turbulent viscosity in different directions, m² per sec; is function emissions of impurities in the atmosphere, which is determined by the equation:

                                                                                                (2)

There I_i is function emissions from i-th source; f_i (t) and are functions describing the mode of operation and location of stationary sources, connected to the radius-vector  and . For continuously operating sources f_i (t) = 1.

Because the movement of air is a subsonic, in accordance with the approximation of the Boussinesq approximation can be described by a system of equations of the Navier-Stokes equations for an incompressible viscous fluid:

                                                                            (3)

There n is dynamic viscosity, Pa·sec; р is piezometric pressure, Pa;  p is the density of the medium (air), kg per m³; is specific force field, N/m³.

Density of air can be found using the equation of state of an ideal gas:

                                                                                                            (4)

There р_атм is atmospheric pressure, Pа; R_m is gas constant, for air R_m = 3,464×10^-3 J per kg×K×mol; Т_ф is background temperature, K.

Kinematic viscosity can be found using the approximation [3]:

h = 6×10^-6 + 4×10^-8×Т_ф.                                                                                                     (5)

Turbulent flow structure, which cannot be solved explicitly for the numerical solution of a system of Navier-Stokes equations, are approximated using the subgrid turbulence Smagorinsky model. This approach proposed by Deardorff and developed in the works of Smagorinsky, involves the allocation of the scale, smaller grid, which is approximated by the turbulence [4]. The preference of this model is given to the fact that it takes into account the presence of turbulence, formed a small vortices while flowing wind flow walls of buildings, structures and other obstacles, but the vortices don’t need to approximate the «wall-functions». This approach due to the reduction of the dimension of the matrix equations by a sequence of calculations reduces the requirements to computing resources of a computer.

The scale of small eddies in the Smagorinsky model determined time-measures Dх, Dу, Dz three-dimensional cell:

                                                                                                           (6)

The coefficients of turbulent viscosity is determined using the system:

                                                                                                            (7)

There k_баз is basic coefficient of turbulent viscosity, and contempt of the temperature gradient low altitude and temperature of the discharged impurities determined the approximate equation:

                                                                                                  (8)

There k_ф is background coefficient of turbulent viscosity, k_ф = 1-15 м²/с; ε = 0,1-0,4; Def (x; y; z) is function of deformation or dissipation defined by the equation:

At the upstream boundary of the computational domain profile of wind speed is given by Karman. Since wind flow can be directed at an angle of the input boundary of the computational domain, the velocity components of the system are given by:

                                                                    (9)

There u* is dynamic speed, m per sec; z₀ is argument of a roughness;  is Karman`s constant,; Н_ср is the average height of wind barriers; С is coefficient of resistance;
α is the angle between the direction of the wind on the input in the computational domain boundary and the x-axis, radian.

At the downstream boundary of the computational domain is given the type of border Outlet, the boundary condition Normal flow / zero pressure:

р = 0.                                                                                                          (10)

On the surfaces of buildings and structures, landfill, land for the components of the wind speed is given by the condition of impermeability and adhesion:

                                                                                                            (11)

If the streamlined surface is the area where is blowing (suction) air velocity components u_в, v_в, w_в, then the area is given by the boundary condition Moving /Leaking wall:

и = и_в; v = v_в; w = w_в.                                                                                          (12)

On the lateral boundaries of the computational domain is specified Symmetry boundary, meaning the absence of leaks and tangential stresses:

                                                                               (13)

There and is normal and tangential unit vector to the boundary surface, unit vector directed outward from the boundary region.

At presence on a surface of the polygon of ground insulation filling and absence of gas drainage wells circuit equations emissions and diffusion components of biogas is produced with the help of the derived equations [5]:

                                                                                     (14)

There D is diffusivity of landfilling (insulating the outside waste), m² per sec; h is thickness of landfilling, m; n_отх is porosity of waste, n_отх = 0,33; γ is permeation coefficient, for gases γ = 0,01-0,015 m per sec; с_{пов,возд} is the concentration of component biogas at the upper side of air filling, mg per m³.

On the surface of the landfill to calculate the concentration of a component of biogas in the absence of gas drainage wells gets and sets boundary condition:

c = с_{пов,возд.}                                                                                                 (15)

If the emission biogas through gas drainage wells or surface landfill, which has no insulating filling, the consideration of the effect of each of them by using boundary condition Flux:

                                                                                        (16)

On impervious surfaces flow of impurities (I_i = 0) is given by boundary condition Isolation/Symmetry:

                                                                                         (17)

On the other boundaries of the computational domain is given by the boundary condition Convective flux:

                                                                                              (18)

When determining the scale of small eddies in the model of the radical work of Smagorinsky DхDуDz can be interpreted as the volume of the rectangular cell using MCS . When using the finite element method with the most common type of cells – tetrahedral most famous software packages such as Ansys CFX, Fluent, Flow Vision, etc. In this case, the volume of each cell is calculated by means of numerical methods. To determine the scale, the following simpler approach. The maximum linear dimension of the finite element and should be much smaller than the calculated area, the growth rate of the element responsible for the degree of condensation, taken strictly to 1. These options allow you to get a thick, almost uniform grid consisting of a set of tetrahedral that are close to correct. Then, in our case for small scale vortices can be approximated as the cube root of the volume of the tetrahedron:

                                                                    (19)
Then, using the approximation, we obtain:

                                                                (20)

In our case, made ​​a = 4 m. At this density grid in [6] by the method of successive approximations for calculating the concentrations of methane emitted at the site ” Centralny” in Volgograd , the optimal values ​​of k_ф = 4 m²/s ; ε = 0,2. This approach eliminates the calculation of sub-grid scale using tetrahedral finite element mesh, thereby simplifying the numerical (software) implementation of the turbulence model and reduces the requirements for compute-intensive computer.

From a practical point of view is suitable stationary statement of the problem. In this case, a method of determining where the problem is solved on a large time interval that the process leads to stationary. Implicit scheme allows to get rid of restrictions to the size of the time step. Stationary statement of the problem significantly reduces the number of iterations, and the consumption of computing resources of a computer.

The solution of the discrete analogues of the differential equations made by bi-conjugate gradients with the stabilization of the solution. The whole program code is more than a dozen pages, so in an article for the sake of brevity, it shows only the main conclusions:

% COMSOL Multiphysics Model M-file

% Generated by COMSOL 3.4 (COMSOL 3.4.0, $Date: 2007/10/03 17:02:19 $)

flclear fem

% COMSOL version

clear vrsn

vrsn.name = ‘COMSOL 3.4′;

vrsn.ext = ‘a’;

vrsn.major = 0;

vrsn.build = 603;

vrsn.rcs = ‘$Name: $’;

vrsn.date = ‘$Date: 2007/10/03 17:02:19 $’;

fem.version = vrsn;

% Constants

% Constants
fem.const = {‘W_s’,’0′, …
‘k_f’,’4′, …
‘epsilon’,’0.2′, …
‘Mcomp’,’5′, …
‘h_iz’,’0.2′, …
‘Vpol’,’100000′, …
‘Diffusiv’,’3.4e-5′, …
‘gamma’,’0.001′, …
‘Ccomp’,’50′, …
‘Pamb’,’1e5′, …
‘T_amb’,’25′, …
‘Udin’,’3′, …
‘Hsr’,’10′, …
‘Z0′,’0.2′, …
‘C’,’0.0115′, …
‘alpha’,’0′, …
‘a’,’4′};

% Geometry

% (Default values are not included)

% Application mode 1
clear appl
appl.mode.class = ‘FlNavierStokes’;
appl.shape = {‘shlag(1,”u”)’,'shlag(1,”v”)’,'shlag(1,”w”)’,'shlag(1,”p”)’};
appl.gporder = 2;
appl.cporder = 1;
appl.assignsuffix = ‘_ns’;
clear prop
prop.analysis=’static’;
appl.prop = prop;
clear pnt
pnt.p0 = {};
pnt.name = {};
pnt.pnton = {};
pnt.ind = [];
appl.pnt = pnt;
clear bnd
bnd.U0out = {};
bnd.v0 = {};
bnd.opentype = {};
bnd.u0 = {};
bnd.Fbnd = {};
bnd.p0 = {};
bnd.type = {};
bnd.velType = {};
bnd.walltype = {};
bnd.w0 = {};
bnd.inttype = {};
bnd.vw = {};
bnd.U0in = {};
bnd.ww = {};
bnd.uw = {};
bnd.name = {};
bnd.outtype = {};
bnd.f0 = {};
bnd.intype = {};
bnd.stresstype = {};
bnd.ind = [];
appl.bnd = bnd;
clear equ
equ.eta = ’6e-6+T_amb*4e-8′;
equ.name = ‘physical parameters of the atmosphere in the zone of landfill’;
equ.rho = ‘Pamb*3.464e-3/T_amb’;
equ.ind = [];
appl.equ = equ;
fem.appl{1} = appl;

% Application mode 2
clear appl
appl.mode.class = ‘FlConvDiff’;
appl.assignsuffix = ‘_cd’;
clear prop
prop.analysis=’static’;
clear weakconstr
weakconstr.value = ‘off’;
weakconstr.dim = {‘lm5′};
prop.weakconstr = weakconstr;
appl.prop = prop;
clear bnd
bnd.d = {};
bnd.Dbnd = {};
bnd.c0 = {};
bnd.name = {};
bnd.N = {};
bnd.type = {};
bnd.ind = [];
appl.bnd = bnd;
clear equ
equ.D = ’4.160167646*k_f+0.707106781*epsilon*(a^2)*((ux)^2+(vy)^2+(wz)^2+0.5*((vx+uy)^2+(wy+vz)^2+(uz+wx)^2))^0.5′;
equ.w = ‘w-W_s’;
equ.v = ‘v’;
equ.u = ‘u’;
equ.name = ‘physical parameters of the atmosphere in the zone of landfill’;
equ.ind = [];
appl.equ = equ;
fem.appl{2} = appl;
fem.sdim = {‘x’,'y’,'z’};
fem.frame = {‘ref’};
fem.border = 1;
clear units;
units.basesystem = ‘SI’;
fem.units = units;

% Scalar expressions
fem.expr = {‘profil_u’,’2.5*Udin*log((z-Hsr+Z0/C)/Z0)*cos(alpha)’, …
‘profil_v’,’2.5*Udin*log((z-Hsr+Z0/C)/Z0)*sin(alpha)’, …
‘Cpov’,'(Mcomp*z_iz*h_izol/Vpol+0.33*Diffusiv*Ccomp)/(Diffusiv+gamma*h_iz)’, …
‘Mud’,'Mcomp*z/Vpol’};

% Descriptions
clear descr
descr.expr= {‘Mud’,'emission component of biogas from the landfill area, mg / (kv.m.sek) (boundary condition of the 2nd kind is used in the absence of landfilling)’,'Cpov’,'concentration of the component of biogas at the landfill surface (boundary condition of the 2nd kind is used in the absence of landfilling)’,'profil_v’,'y-oic wind component on the input boundary of the computational domain’,'profil_u’,'x-oic wind component on the input boundary of the computational domain’};
fem.descr = descr;

% Descriptions
descr = fem.descr;
descr.const= {‘h_iz’,'thickness of the insulating filling (default made ??0.2 m)’,'Pamb’,'atmospheric pressure Pa’,'Vpol’,'volume occupied by the solid waste landfill or softwareб cubic m’,'Hsr’,'average height of wind barriers, m’,'Diffusiv’,'diffusivity of the soil from which the filling,square m/seс’,'a’,'maximum line size tetraedricheskogo finite element, m’,'C’,'roughness parameter’,'k_f’,'background coefficient eddy viscosity Smagorinsky model, square m/sec (default is assumed to be 4)’,'Mcomp’,'emission component of the biogas emitted from around the landfill or software mg/sec’,'Udin’,'dynamic speed, m/s’,'Z0′,’resistance coefficient, m’,'W_s’,'settling velocity of the impurities in the atmosphere for light inert gas impurities 0; Heavy 0.001, 0.008 for aerosols m/sec’,'Ccomp’,'the concentration of the components in the biogas at the time of its release in the body of the landfill, mg/cubic m’,'gamma’,'coefficient of gas seepage through the soil, m/sec (default is 0.001)’,'alpha’,'angle between the direction of the wind at the entrance to the settlement area boundary and the x axis, radian’,'epsilon’,'constant in the Smagorinsky model (the default is assumed to be 0.2)’,'T_amb’,'background air temperature, K’};
fem.descr = descr;

% ODE Settings
clear ode
clear units;
units.basesystem = ‘SI’;
ode.units = units;
fem.ode=ode;

% Multiphysics
fem=multiphysics(fem);

The settlements were made on the computer AMD FX™-4100 Quard-Core Processor, RAM 4 Gb, 3,2 GHz, OS MS Windows 7 Ultimate SP1. The calculation time for landfill «Centralny» was about 30 hours. The results of calculations are shown in figures 1-2 (unit mol per m³ treated as mg per m³).

Figure 1 – The field of wind speed, m per sec, at the height of 1.8 m above the top of the landfill site landfill PTO-3 «Novosyolki» 26.08.2001

Figure 2 – Field concentrations of methane, mg per m³, at the height of 1.8 m above the top of the landfill site PTO-3 «Novosyolki» 26.08.2001

Subgrid modeling is characterized by a kind of subgrid scale D. The most common definition of subgrid scale dimensions for rectangular cells Dx, Dy, Dz at a moderate anisotropy of the grid as follows:

                                                                                                 (1)

and for strong anisotropy of grid as follows:

                                                                                         (2)

Turbulent air flow occurring at subsonic speeds, in accordance with the «hypoacoustic» Boussinesq approximation can be described by the Navier-Stokes equations consisting of equations of motion and continuity for an incompressible viscous fluid:

                                                              (3)

Here is velocity vector;
h is dynamic viscosity, Pa∙s; р is piezometric pressure, Pa;  is specific force field, N per cubic m; p is air density, kg per cubic m.

The system (1) is applicable for finding eddies of various scales in its analytical solution, but it is an unsolved mathematical problem. Among the numerical methods for the solution is the most accurate direct numerical simulation (DNS) – the solution of unsteady Navier-Stokes equations with a small time step on the dense grid , but it is now possible computing still do not allow the DNS to the large settlement areas. Therefore , in practice, often authors suggest solving Reynolds averaged in the system (2) the equation of motion (RANS):

                                                 (4)

There h_t is dynamic coefficient of turbulent viscosity, Pa∙s, h_t = rk_хуz; k_хуz is eddy viscosity in different directions, m²

per s, for an anisotropic medium is given by the matrix .

The coefficients of turbulent viscosity in subgrid Smagorinsky model defined by the system:

                                                                            (5)

Here k_баз – is basic coefficient of turbulent viscosity, and contempt of the temperature gradient low altitude and temperature of the discharged impurities determined the approximate equation:

;                                                                          (6)

Here kф is background coefficient of turbulent viscosity, kф = 1-15 м2/с; ε = 0,1-0,4; Def (x; y; z) is function of

deformation or dissipation defined by the equation:

Most software packages such as Ansys CFX, Fluent, Flow Vision for the calculation for anisotropic media digested TBE on sub-elements within each of which can be regarded as an isotropic medium (Figure 1). To simplify the calculation of turbulent flow structure, the present author proposed a model to produce isotropization subgrid of turbulent viscosity determined by Smagorinsky model for an isothermal environment.

                                                      Figure 1 – Example of splitting finite element on the sub-elements [1]

The radical product DхDуDz in definition (1) can be interpreted as the volume of the rectangular cell, equal to the amount that would be occupied with the cubic cell edge D. In practice, the most common use is not rectangular and tetrahedral cells. Scale D cells form a regular tetrahedron volume Ω, by analogy with definition (1) can be found as:

                                                                 (7)

Here а is edge of tetrahedral cell.

Then coefficients of turbulent viscosity for grid with small anisotropy will be determined as:

                                                             (8)

For computational domains with real geometry to build isotropic mesh is practically impossible. Therefore, by analogy with definition (2) is physically more correctly we only consider the maximum size of the cell edge:

.                                                  (9)

Here а_mах is maximum element size.

The expression (9) for example tetrahedral mesh is a kind of generalization of the two definitions scale D. This eliminates the need to calculate the subgrid scale for each grid cell.

Example of constructing a structured mesh for the computational domain of landfill PTO-1 (St. Petersburg) is shown in Figure 2.

Figure 2 – Example of a structured grid (built in Comsol Multiphysics)

To construct the proposed structured grid should adhere to the following rules:

1. The growth rate of TBE tetraedricheskoy grid responsible for the degree of thickening, taken strictly equal to 1.

2. The maximum line size amah given considerably smaller than the calculated area to get a thick, close to the isotropic mesh.

To subgrid turbulent viscosity considered isotropic must comply with condition k_хуz = const. This condition can be performed using the calculation of velocity field Lagrangian finite elements with linear approximation. In this case, within each end element derivatives of the velocity components и, v и w on the coordinate axes are constants then Dеf = const then k_хуz = const.

Asking subgrid isotropic of turbulent viscosity and reduces the computation time for the approximation of the finite element method of the differential equation of turbulent diffusion, as eddy viscosity within a finite element can be considered constant.

To determine the external and internal contamination of the air environment of buildings near landfills biogas components developed mathematical model, the equations of which are given below.

Because air movement is a subsonic, it can be described by a system of Navier-Stokes equations in the Boussinesq approximation:

;                                                                       (1)

here r₀ is background density of air at a certain equilibrium temperature, kg/m³; is velocity vector of air (wind); h= h(Т) is dynamic viscosity of air, Pa×sec.

Specific power load for interior subregion is defined as:

                                                                                                   (2)

outdoor subdomains:

                                                                                                       (3)

here r = r(Т) is air density, kg/m³.

Density and background density of the air can be found using the equation of state for an ideal gas:

r = р_атм /(R_mТ);                                                                                                              (4)

r₀ = р_атм /(R_mТ_ф);                                                                                                            (5)

here R_m is gas constant of air, R_m = 287 J/(kg×K×mol); Т – temperature , К; Т_ф – background temperature, К.

For the calculation of the temperature fields, the system (1) is supplemented by the heat equation:

                                                                                              (6)

here С_р = С_р(Т) is isobaric heat capacity of air, J/(kg×K); λ = λ(Т) is thermal conductivity, W/(m∙K); Q_heat is source or sink of heat, W/m³.

Dispersion of passive tracer with concentration c, mg/m³, described unsteady turbulent diffusion equation:

                                                                                       (7)

here k_хуz is turbulent viscosity coefficient, m²/s, for anisotropic media k_хуz = diag{k_х; k_у; k_z};  w_s is sedimentation rate of the impurity, m/s;  I (r; t) is emission function impurities into the atmosphere.

To calculate the field of impurity concentrations given amount of air in the room is possible, which can be determined by converting the equation Lang in the following form [1]:

                                                                                                        (8)

here с_прист is concentration on the surface of the outer wall of the building, mg/m³; i_вп is coefficient of permeability of the fencing construction, kg/m∙s∙Pa; S_ок is area enclosing structure, m²; δ is material thickness, m; ρ_н is average density of the external and internal air, kg/m³.

Computer implementation of the mathematical model is made using the software Comsol Multiphysics. The results of calculations on the outer subdomains fields of wind speed, pressure and concentration of the components of biogas near landfill “Centralny” of Volgograd listed in the overview chapter are shown in Figures 1-3. Unit mol/m³ treated as mg/m³ concentration fields are calculated without taking into account the background levels.

Figure 1 – Field of annual average wind speed, m /sec, near landfill “Centralny” at a height of 2 m

Figure 2 – The pressure field, Pa, near the landfill “Centralny” at a height of 2 m

Figure 3 – Field of annual average surface concentrations of methane mol/m³ in landfill “Centralny” in 2007

Figures 7-9 shows the results of the velocity fields of movement, temperature and ammonia concentrations in the indoor air of the building near landfill “Central” of Volgograd. For calculations considered office space on the ground floor area of 18 m², volume of 46 m³, equipped and unframed walling vent diameter of 100 mm (eg HL 900N NECO). Pressure difference between indoor and outdoor air adopted 56 Pa, outdoor temperature adopted +7 °C, thermal resistance of the outer wall and the window unit to the exterior wall R_с = 3,59 m²∙K/W, window R_ок = 4,089 m²∙K/W [2]. Dimensions of the window unit taken 1,7х1,4 m. Heat exchange with the adjacent spaces are not taken into account. The heater is regarded as a cuboids length 1,3 m, width 0,15 m, height 0,5 m on the surface of the device temperature of 66 °C. The adopted Remove air from the room through a slit height of 0,01 m under the closed door.

Figure 4 – The velocity field of air, m/sec, in a room with a vent on the ground floor near the landfill “Centralny”

Figure 5 – Temperature field, K, in a room with a vent on the ground floor near the landfill “Centralny”

Figure 6 – Field of ammonia concentrations, mg/m³, in a room with a vent on the ground floor near the landfill “Centralny”

Figure 7 – The velocity field of air, m/s, in a room without air vent on the ground floor near the landfill “Centralny”

Figure 8 – The temperature field, K, in a room without air vent on the ground floor near the landfill “Centralny”

Figure 9 – Field methane concentrations, mg/m³, in a room without air vent on the ground floor near landfill “Centralny”

To reduce air pollution biogas system has been improved its production, purification and collection.

Extraction of biogas produced from gas drainage wells. Assuming that the pressure on the surface of the landfill does not differ from the atmospheric sectional area wells S_скв and amount n_скв can be defined as:

                                                                                                (9)

there m_l is weight l-th component of biogas, tons/year; р_атм is atmospheric pressure, Pa; R_l is gas constant, J/(kg×K×mol); N is the number of components of biogas, which is being payment; is speed biogas wells, m/s, not more than 0,1 m/s.

Specific mass of component of biogas m_уд, g/s, emitted from each well is defined as:

                                                                                            (10)

Surface proposed landfill cover with a film of thermoplastic elastomers. They have a high resistance to oil, fuel and water, exposure to the weather and climatic conditions. This film also has a high mechanical strength and wears resistance.

Figure 10 depicts a schematic diagram of the proposed production and collection of biogas emitted by landfills.

Figure 10 – Scheme of extraction, purification and collection of biogas from landfills

Biogas from landfill gas drainage wells at open valves 1 enters the manifold 2, whence by the compressor 4 is fed into a centrifugal separator 5 for gas purification from moisture and dust. In view of explosion safety gas supply to a separator and subsequent separation of thermosensitive portions of the pipeline shut-off valve equipped with 3 and 6. The gas enters the purification unit of the carbon dioxide and hydrogen sulphide 7. Carbon dioxide is emitted into the air, and the hydrogen sulfide reacts with the iron oxide (III) and is absorbed. From halogenated hydrocarbons, ammonia, and residual gas is purified of other impurities zeolite filter 8 (Ме_2/nО∙Аl₂О₃∙хSiО_2уН₂О). Purified gas to acquire odor mixed ethyl mercaptan (СН₃SН) by setting 9, and then liquefied by the compressor 10 and is supplied to the gas-holder 12, which is liquefied and after the pressure reducer gas is fed into a gas pipeline or refueling gas cylinders 15. In order to land a gas pipeline explosion safety before the gas holder and it is also equipped with temperature-sensitive shut-off valves 11 and 13. This system is a semi-automatic and does not require constant intervention of the staff and most of the elements may be located in the building of administrative area landfills. Water-dust mixture, the resulting separation, reaction products with zeolites is disposed at the landfill. Accumulated biogas meets the requirements for natural gas when used for gas supply. Since methanogens occurs at the site limited number of years, the gas supply system should be compact, in case of need to be dismantled relatively quickly.

Laying pipelines abroad housekeeping area landfill entails additional difficulties associated with construction works. Therefore, it is advisable to supply excess biogas in cylinders. Figure 11 as an example of a perspective diagram of proposed buildings gas housekeeping area landfill “Centralny”, where «I» crossing pipelines connected to the gas drainage wells acts as a collector (equalization) of the gas stream. Compressors, cleaning plant and adding ethyl mercaptan are located in the left building. Removing carbon dioxide from it by means of ventilation.

Figure 11 – Scheme of gas supply buildings housekeeping area landfill “Centralny”

Landfill gas energy potential can be estimated V_{прир.газа}, thousand m³, showing how much you can save natural, if used for the entire gas evolved biogas:

                                                                                                   (11)

here χ is coefficient reflecting the gas leak from its production and supply (in Russia, USA, Germany and Netherlands adopted χ = 0,99); k_{сж.газа} = 1,57 and k_{прир.газа} = 1,154 are coefficients for conversion to tons of equivalent fuel.

When using biogas for gas supply buildings located near landfills, reduced pollution of air and concentrations of most pollutants contained in the biogas may be considered as the background (other than carbon dioxide). Table 1 shows as an example the values of surface concentration of methane in 2007, contained in the ambient air near buildings located near landfill “Centralny” From the warm period during 2006 and providence collection and treatment of biogas.

Table 1 – Surface methane concentration in 2007 in the outdoor air near buildings located at the landfill “Centralny”

Also reduce air pollution inside buildings. Table 2 shows the concentration of methane and ammonia inside the building premises calculated housekeeping area landfill “Centralny”.

Table 2 – Concentrations of pollutants in the air in the buildings of the estimated landfill near the “Centralny”

Payback period is determined according to the schedule in Figure 12, which shows that it would be approximately 1,4 years.

Figure 12 – Graph of the payback period