**2. Effluent cleaning with materials derived from rice and beer production wastes**

Industrial effluents often have high flows with variable concentrations of toxic substances, where adsorption is an ideal process for their decontamination due to its good economic turnover and the possibility of recovering the contaminants by desorption. The process of adsorption is based on the diffusion of sorbates to the adsorbent surface, followed by the inclusion inside the pore structure where they are stored. Here the textural properties of the adsorbents (surface area and porosity) are of the utmost importance [5].

Distilleries Muñoz Galvez (DMG) is a leading Spanish Company that manufactures and exports Essential Oils and Aromatic Raw Materials (Fine Chemicals) as well as Fragrances and Flavours worldwide [6]. The challenge faced by the research group (CDTI project) [7] was to clean DMG wastewaters that contained terpenes as the main residue, as expected given their origin, thus reducing water consumption, economic expenditure and possible environmental hazards. Aiming to decrease the economic costs, and increase the project´s environmental approach, agriresidues from beer and rice production were used to prepare materials capable of wastewater decontamination that were compared to commercial adsorbents. Previous knowledge of the researchers was applied and optimised to the wastewater composition and treatments [8,9]. The results indicated better adsorption and therefore cleaning capacities in the residue derived materials than in the commercial ones. The chemical oxygen demands after wastewater treatment were low enough for the treated water to be discharged in accordance with the legal requirements.

The agriresidues chosen for this study were beer bagasse and rice husk. Beer bagasse, from Mahou San Miguel (Spain) [10] (designated as BBM), is a residue from beer production that has *ca*. 75-80% water. Previous work by the authors has demonstrated that materials prepared from beer bagasse are basic due to their high P, Si, Ca and Mg content. Furthermore, due to their origin these materials are competitive in price; in fact BBM is at present used as a fertiliser [11].

Rice husk (RH) from DACSA (Spain) [12] is an agriresidue from rice production, of difficult storage and transport due to its high volume to weight ratio. On calcining this residue, a material with more than 97% silica is produced, that has also low amounts of calcium and potassium [13-15].

The agriresidues utilized as raw materials in this study were used as received, in the case of rice husk, or after a drying step at 150°C in the case of the BBM, to inhibit further fermentation due to its high water content. The RH and the dried BBM were analysed by TG-DTA in air to determine their thermal stabilities and design the material preparation. Details of experimental set up can be found in [14]. Figure 1 shows these data.

**Figure 1.** TG-DTA analyses of RH and BBM agriresidues in air. **Figure 1.** TG-DTA analyses of RH and BBM agriresidues in air.

enzyme immobilisation and use in biodiesel preparation and Bioecomaterials for tissue

**2. Effluent cleaning with materials derived from rice and beer production**

Industrial effluents often have high flows with variable concentrations of toxic substances, where adsorption is an ideal process for their decontamination due to its good economic turnover and the possibility of recovering the contaminants by desorption. The process of adsorption is based on the diffusion of sorbates to the adsorbent surface, followed by the inclusion inside the pore structure where they are stored. Here the textural properties of the

Distilleries Muñoz Galvez (DMG) is a leading Spanish Company that manufactures and exports Essential Oils and Aromatic Raw Materials (Fine Chemicals) as well as Fragrances and Flavours worldwide [6]. The challenge faced by the research group (CDTI project) [7] was to clean DMG wastewaters that contained terpenes as the main residue, as expected given their origin, thus reducing water consumption, economic expenditure and possible environmental hazards. Aiming to decrease the economic costs, and increase the project´s environmental approach, agriresidues from beer and rice production were used to prepare materials capable of wastewater decontamination that were compared to commercial adsorbents. Previous knowledge of the researchers was applied and optimised to the wastewater composition and treatments [8,9]. The results indicated better adsorption and therefore cleaning capacities in the residue derived materials than in the commercial ones. The chemical oxygen demands after wastewater treatment were low enough for the treated water to be discharged in accordance

The agriresidues chosen for this study were beer bagasse and rice husk. Beer bagasse, from Mahou San Miguel (Spain) [10] (designated as BBM), is a residue from beer production that has *ca*. 75-80% water. Previous work by the authors has demonstrated that materials prepared from beer bagasse are basic due to their high P, Si, Ca and Mg content. Furthermore, due to their origin these materials are competitive in price; in fact BBM is at present used as a fertiliser [11].

Rice husk (RH) from DACSA (Spain) [12] is an agriresidue from rice production, of difficult storage and transport due to its high volume to weight ratio. On calcining this residue, a material with more than 97% silica is produced, that has also low amounts of calcium and

The agriresidues utilized as raw materials in this study were used as received, in the case of rice husk, or after a drying step at 150°C in the case of the BBM, to inhibit further fermentation due to its high water content. The RH and the dried BBM were analysed by TG-DTA in air to determine their thermal stabilities and design the material preparation. Details of experimental

engineering and controlled desorption of bioactive substances.

adsorbents (surface area and porosity) are of the utmost importance [5].

**wastes**

188 Agroecology

with the legal requirements.

potassium [13-15].

set up can be found in [14]. Figure 1 shows these data.

From these results the agriresidues loose up to 90 (BBM) and 87 (RH) percent weight, when calcined up to 800ºC, where the weight losses were an endotherm due to water loss up to 200 ºC and two exotherms at 340 ºC and 520 ºC (BBM) or 340 ºC and 470 ºC (RH) due to decomposition/transformation of the organic matter to volatile organic substances and carbonization [14]. After studying the reproducibility of the materials the temperature chosen to prepare the adsorbents through thermal treatment of the agriresidues was 350 ºC for 2, 4 or 6 h. These materials were designated as BBM2, BBM4, BBM6, RH2, RH4 and RH6. The From these results the agriresidues loose up to 90 (BBM) and 87 (RH) percent weight, when calcined up to 800°C, where the weight losses were an endotherm due to water loss up to 200 °C and two exotherms at 340 °C and 520 °C (BBM) or 340 °C and 470 °C (RH) due to decompo‐ sition/transformationoftheorganicmattertovolatileorganicsubstancesandcarbonization[14].

composition analyses of these agriresidue derived materials are included in Table 1. From these results it was clear that under these conditions the materials derived from BBM were mainly carbonaceous whilst those derived from RH have siliceous structure and the content of the elements that form volatile species (CO2, H2O, NOX, oxychlorides, *etc*.) decreased on increasing the time of thermal treatment, while the percentage of the other elements increased. **BBM2 BBM4 BBM6 RH2 RH4 RH6 C** 43.1 43.2 40.1 7.0 1.8 1.0 **H** 1.6 1.6 1.6 0.7 0.4 0.3 After studying the reproducibility of the materials the temperature chosen to prepare the adsorbents through thermal treatment of the agriresidues was 350 °C for 2, 4 or 6 h. These materials were designated as BBM2, BBM4, BBM6, RH2, RH4 and RH6. The composition analyses of these agriresidue derived materials are included in Table 1. From these results it was clear that under these conditions the materials derived from BBM were mainly carbona‐ ceous whilst those derived from RH have siliceous structure and the content of the elements that form volatile species (CO2, H2O, NOX, oxychlorides, *etc*.) decreased on increasing the time of thermal treatment, while the percentage of the other elements increased.


**Table 1.** Percent composition of agriresidue derived materials (Traces: Ti, Cr, Ni, Ga, Br, Rb, Mn, Sr, Cu).

porosity, in agreement with TG-DTA analyses.

are included in Figure 2 and Table 2. Description by the authors of the experimental analyses for MIP can be found in reference 16. In this technique, the pores below 300 nm correspond to those inside the particles, while those at higher values are due to interparticle voids. As can be seen in all the materials prepared, the curves coincide for values below 1000 nm. As expected, in general, there was an increase in the total pore volume on increasing the calcination time, due to decomposition of volatile compounds, producing extra Textural analyses of the agriresidue derived materials were carried out by mercury intrusion porosimetry (MIP) and the data obtained are included in Figure 2 and Table 2. Description by the authors of the experimental analyses for MIP can be found in reference 16.

In this technique, the pores below 300 nm correspond to those inside the particles, while those at higher values are due to interparticle voids. As can be seen in all the materials prepared, the curves coincide for values below 1000 nm. As expected, in general, there was an increase in the total pore volume on increasing the calcination time, due to decomposition of volatile compounds, producing extra porosity, in agreement with TG-DTA analyses.

**Figure 2.** MIP textural data of agriresidue derived materials. **Figure 2.** MIP textural data of agriresidue derived materials.

**Figure 3.** GCMS analysis of DMG wastewater.

and analysed by GCMS (Figures 4 and 5).


*Pore Volume, dp = medium pore size.*  From this data it can be observed that the porosity, surface area and medium pore size increase with time of calcination and the **Table 2.** Textural characteristics of agriresidue derived materials and an Activated Carbon by MIP. *(SHg= Specific surace area, Vp = Pore Volume, dp = medium pore size.*

surface areas were lower but the pore sizes higher for the residue derived materials compared to the commercial activated carbon. The analysis of DMG wastewater was carried out by GCMS (Figure 3), the experimental details for this technique can be found in reference 17. From these analyses the presence of *ca.* 16 different substances was found (Figure 3) and for the quantification of the cleaning studies, the main substances (9.5 min (pinene), 13.6 min (limonene), 18.1 min (hexadecyl acetate), 19.5min (C19H40), 22 From this data it can be observed that the porosity, surface area and medium pore size increase with time of calcination and the surface areas were lower but the pore sizes higher for the residue derived materials compared to the commercial activated carbon.

min (C20H42), 26.2 min (C21H44) and 27.5 min (C22H46) were chosen. The analysis of DMG wastewater was carried out by GCMS (Figure 3), the experimental details for this technique can be found in reference 17. From these analyses the presence of *ca.* 16 different substances was found (Figure 3) and for the quantification of the cleaning studies, the main substances (9.5 min (pinene), 13.6 min (limonene), 18.1 min (hexadecyl acetate), 19.5min (C19H40), 22 min (C20H42), 26.2 min (C21H44) and 27.5 min (C22H46) were chosen.

The DMG wastewater treatments were carried out by using 0.5 g of carbon (commercial or Ecomaterial), and 30 mL of the DMG wastewater (to ensure reproducibility of the measurements), these slurries were magnetically stirred and 2 mL aliquots of the original and treated wastewaters were extracted at increasing times with the same volume of di-isopropylether, dried over sodium sulphate

Effluent Cleaning, Greener Catalysts and Bioecomaterials from Agricultural Wastes http://dx.doi.org/10.5772/60018 191

**Figure 3.** GCMS analysis of DMG wastewater.

Textural analyses of the agriresidue derived materials were carried out by mercury intrusion porosimetry (MIP) and the data obtained are included in Figure 2 and Table 2. Description by

In this technique, the pores below 300 nm correspond to those inside the particles, while those at higher values are due to interparticle voids. As can be seen in all the materials prepared, the curves coincide for values below 1000 nm. As expected, in general, there was an increase in the total pore volume on increasing the calcination time, due to decomposition of volatile

the authors of the experimental analyses for MIP can be found in reference 16.

compounds, producing extra porosity, in agreement with TG-DTA analyses.

**Figure 2.** MIP textural data of agriresidue derived materials.

**Figure 2.** MIP textural data of agriresidue derived materials.

min (C20H42), 26.2 min (C21H44) and 27.5 min (C22H46) were chosen.

*Pore Volume, dp = medium pore size.* 

190 Agroecology

*area, Vp = Pore Volume, dp = medium pore size.*

**Figure 3.** GCMS analysis of DMG wastewater.

and analysed by GCMS (Figures 4 and 5).

SHg (m2 /g)

**SHg (m2 /g)**

Vp (cm3 /g)

**Vp (cm3 /g)**

BBM2 16 0.18 66.7 25.4 BBM4 18 0.18 69.2 44.7 BBM6 20 0.19 75.9 67.1 RH2 27 0.24 81.0 36.1 RH4 33 0.25 82.3 48.3 RH6 38 0.26 84.7 67.9 Fluesorb B 52 0.22 44.6 10.2

BBM2 16 0.18 66.7 25.4 BBM4 18 0.18 69.2 44.7 BBM6 20 0.19 75.9 67.1 RH2 27 0.24 81.0 36.1 RH4 33 0.25 82.3 48.3 RH6 38 0.26 84.7 67.9 Fluesorb B 52 0.22 44.6 10.2

**Table 2.** Textural characteristics of agriresidue derived materials and an Activated Carbon by MIP. *(SHg = Specific surace area, Vp =* 

**Table 2.** Textural characteristics of agriresidue derived materials and an Activated Carbon by MIP. *(SHg= Specific surace*

From this data it can be observed that the porosity, surface area and medium pore size increase with time of calcination and the surface areas were lower but the pore sizes higher for the residue derived materials compared to the commercial activated carbon. The analysis of DMG wastewater was carried out by GCMS (Figure 3), the experimental details for this technique can be found in reference 17. From these analyses the presence of *ca.* 16 different substances was found (Figure 3) and for the quantification of the cleaning studies, the main substances (9.5 min (pinene), 13.6 min (limonene), 18.1 min (hexadecyl acetate), 19.5min (C19H40), 22

From this data it can be observed that the porosity, surface area and medium pore size increase with time of calcination and the surface areas were lower but the pore sizes higher for the

The analysis of DMG wastewater was carried out by GCMS (Figure 3), the experimental details for this technique can be found in reference 17. From these analyses the presence of *ca.* 16 different substances was found (Figure 3) and for the quantification of the cleaning studies, the main substances (9.5 min (pinene), 13.6 min (limonene), 18.1 min (hexadecyl acetate),

19.5min (C19H40), 22 min (C20H42), 26.2 min (C21H44) and 27.5 min (C22H46) were chosen.

residue derived materials compared to the commercial activated carbon.

The DMG wastewater treatments were carried out by using 0.5 g of carbon (commercial or Ecomaterial), and 30 mL of the DMG wastewater (to ensure reproducibility of the measurements), these slurries were magnetically stirred and 2 mL aliquots of the original and treated wastewaters were extracted at increasing times with the same volume of di-isopropylether, dried over sodium sulphate

Porosity (%)

**Porosity (%)**

dp (nm)

**dp (nm)** The DMG wastewater treatments were carried out by using 0.5 g of carbon (commercial or Ecomaterial), and 30 mL of the DMG wastewater (to ensure reproducibility of the measure‐ ments), these slurries were magnetically stirred and 2 mL aliquots of the original and treated wastewaters were extracted at increasing times with the same volume of di-isopropylether, dried over sodium sulphate and analysed by GCMS (Figures 4 and 5).

**Figure 4.** DMG Wastewater cleaning on BBM2.

**Figure 5.** DMG Wastewater cleaning on Fluesorb B.

These results indicated that the carbon prepared from beer residues had better adsorption capacities for cleaning the DMG wastewater than the commercial one, especially with regards to the high molecular weight substances. This can be related to the different textures, since the commercial carbon has smaller pores that can not easily accommodate the high molecular weight substances. The chemical oxygen demand (COD) of the original and treated wastewa‐ ters was studied according to the Spanish UNE 77004, equivalent to ISO 6060:1989:

$$\text{DQO} : \frac{800 \times \text{C} \times \left(V\_1 - V\_2\right)}{V\_0}$$

where C: concentration of Fe(II) sulphate and ammoniumin mol/L, V0: volume in mL before dilution, V1: volume in mL of Fe(II) sulphate and ammonium solution for blank analysis, V2: is the volume in mL of Fe(II) sulphate and ammonium solution for assay, 8000 is molar mass in mg/L of ½ O2. The COD results are in mg O2/L. The value of the method has been checked with a 0.425 g of potassium hydrogenphtalate (KC8H5O4), dried at 105°C, diluted in 1000 mL distilled water with a COD standard value of 500 mg O2/L (+/- 20). Variabilities in COD analyses were less than 2 % [18]. The results obtained for the COD reduction of the wastewater, with the different materials are included in Table 3 (Percent reduction of COD after room temper‐ ature wastewater treatment with adsorbents until constant COD (usually *ca*. 60 minutes).


**Table 3.** Percent COD reduction of DMG wastewater with adsorbents.

The high effectiveness of the residue derived materials compared with the commercial carbon should be noted. The material with greater cleaning ability was RH6 (73% reduction), which allowed a water with COD of 960 mg O2 /L. Comparing the textural data with COD determi‐ nations, it can be said that there was a direct correlation between the pore diameter of the solids and their COD reduction capacity. Thus, wastewater treatment with residue derived materials has been shown to be an economical and environmentally sound process that should be further developed [19].
