**4. Case of study**

In order to understand the model, a set of tests were carried out based on nine (9) potential cases, considering the following conditions:


The use of the model for the decision-making process begins with the input of the information related to the area selected in order to determine the site's aptitude. The aptitude is valued in a general/ global manner considering some variables such as the slope and the depth of soil and groundwater.

The software requires the input of the concentration of the constituents corresponding to the wastewater to be applied (see Table 6). Three BOD5 concentrations (1,000, 25,000, and 50,000 mg/l) were used for the tests. Those concentrations are frequently found in the food and beverage industry effluents.

Characterization of Industrial Highly Organic Wastewater to Evaluate Its Potential Use as Fertilizer in Irrigation… http://dx.doi.org/10.5772/59999 75


**Figure 7.** Input of wastewater information

Ln nitrogen = Hydraulic nitrogen load based on the nitrogen load [mm/d]

The determination of the required area for the application of wastewater in the soil is obtained from the relation between the volume of wastewater discharge and the hydraulic load rate to

> d <sup>Q</sup> A \*F

In order to understand the model, a set of tests were carried out based on nine (9) potential

**2.** For all the cases, the wastewater is used to irrigate soils with agricultural potential: Deep

**3.** The climate conditions are similar for all cases. The considered average precipitation is

**4.** The most important constituents in the wastewater to be used are: Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), and Total Suspended Solids (TSS).

The use of the model for the decision-making process begins with the input of the information related to the area selected in order to determine the site's aptitude. The aptitude is valued in a general/ global manner considering some variables such as the slope and the depth of soil

The software requires the input of the concentration of the constituents corresponding to the wastewater to be applied (see Table 6). Three BOD5 concentrations (1,000, 25,000, and 50,000 mg/l) were used for the tests. Those concentrations are frequently found in the food and

For these tests, DBO5 values of 1,000, 25,000 and 50,000 mg/l were evaluated.

soils (1.5 m to 3 m), with slopes less than 15° and with a loamy texture.

Ln <sup>=</sup> (15)

Cnitrogen = Nitrogen concentration in the waste water [mg/l or g/m3]

be applied in the soil, as shown in Equation 14 [6, 9, 12].

A = Area required for the wastewater application [ha]

Q = Wastewater discharge volume [m3/d] Lnd = Design hydraulic load rate [mm/d]

cases, considering the following conditions:

**1.** The selected crop in all the cases was sugar cane.

F = Conversion factor

74 Agroecology

**3.7. Application area**

F = Conversion factor

**4. Case of study**

730 mm/year.

and groundwater.

beverage industry effluents.

Next, the software requires the input of information related to the characteristics of the soil (Figure 8). It is important to mention that the tests were performed considering loam, clay loam, and sandy loam textures for the soil. The diameter of the particles varied between 0.05 and 0.002 mm. These characteristics are related to other physical properties of the soil such as porosity and infiltration.

Additionally, the model requires information related to the type of crop present and the climatic conditions of the environment. For the performance tests, sugar cane crops with average precipitation conditions (730mm/year) were considered.


**Figure 8.** Input of soil characteristics

Once the information input is completed, the model calculates the optimum parameters for the wastewater application based on the available information. Figure 9 shows an example of the obtained results.

**Figure 9.** Advanced results

The results obtained from all performed tests in the hypothetical cases are detailed in Table 6. Those results show the model estimates of the required surface for the application and the estimated time lap between applications in order to achieve an adequate use of the nutrients provided by the wastewater, which will be required for the crop development.


**Table 6.** Model tests results

The analysis of the results of the tests from the STAR ASA model could determine that the higher the concentration of organic matter in the wastewater, the larger the requirement of agricultural area. However, this quantity depends strongly on the characteristics of the soil. The smaller the soil particle size, the smaller the required area (Figure 10).

Characterization of Industrial Highly Organic Wastewater to Evaluate Its Potential Use as Fertilizer in Irrigation… http://dx.doi.org/10.5772/59999 77

**Figure 10.** Results — application surface

Once the information input is completed, the model calculates the optimum parameters for the wastewater application based on the available information. Figure 9 shows an example of

The results obtained from all performed tests in the hypothetical cases are detailed in Table 6. Those results show the model estimates of the required surface for the application and the estimated time lap between applications in order to achieve an adequate use of the nutrients

**TEST BOD [mg/l] Texture Surface (Ha) Time (h)** 1000 Loam 0.11 6.48 1000 Sandy Loam 0.14 5.76 1000 Sandy Loam 0.10 11.28 25000 Loam 4.03 22.32 25000 Clay Loam 4.63 16.8 25000 Clay Loam 4.66 46.56 50000 Loam 9.18 50.64 50000 Clay Loam 7.91 28.8 50000 Clay Loam 14.89 149.04

The analysis of the results of the tests from the STAR ASA model could determine that the higher the concentration of organic matter in the wastewater, the larger the requirement of agricultural area. However, this quantity depends strongly on the characteristics of the soil.

The smaller the soil particle size, the smaller the required area (Figure 10).

provided by the wastewater, which will be required for the crop development.

the obtained results.

76 Agroecology

**Figure 9.** Advanced results

**Table 6.** Model tests results

The time required between wastewater applications depends mostly on the soil's characteris‐ tics. The smaller the particle size, the shorter the required time lap (Figure 11). This result is related to the infiltration capacity of the soils. The larger the particle size, the smaller the water retention period in the agricultural areas. Therefore, frequent application on sandy soils can cause the lixiviation of the nutrients and chemicals into the groundwater.

**Figure 11.** Results — time period between applications
