**9. Sludge management test generated from the adsorption of heavy metals**

One of the problems of the environment is the accumulation of solid waste. In order not to generate a simple transfer of pollution and in order to valorize the proposed treatment process, the solid sludge component generated by this treatment process "raw chitin saturated with heavy metals" should not weigh down the pollutant mass of household waste. From then we proposed at the end of this chapter two solutions to get rid of the generated sludge:

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*Sustainable Treatment of Heavy Metals by Adsorption on Raw Chitin/Chitosan*

• The first is the elimination of this sludge by calcination at high temperature.

Incineration can greatly reduce the volume and weight of household waste by transforming it into gas, heat, and sterile and inert materials, ashes and slag. Volume and weight reductions can 90 and 60%, respectively of the initial volume and weight of the garbage. The gases formed contain mainly excess air, water vapor, carbon dioxide (CO2), nitrogen oxides (NO×) fly ash, and in small quantities, various products from combustion: carbon monoxide (CO), organic matter, sulfur dioxide (SO2), hydrochloric acid, etc. The incineration takes place in three phases to know: drying with evaporation of water, spraying materials organics from 200°C and gasification of combustion of the carbonaceous residue: the volatile substances emitted burn at 500°C, this combustion is considered complete at 1000°C, provided that the air/fuel contact is satisfactory and the residence time at this high tempera-

After the adsorption tests, the precipitates obtained loaded with the heavy metals are dried at 200°C in an oven and then calcined at high temperature (800°C) using a tubular oven for 2 hours, at the entry of the sample, the release of C, CO2, and H2O. Generally, when burning a conventional hydrocarbon fuel, one obtains at the end of the combustion, two harmless products CO2 and H2O, which result from the complete oxidation of the carbon and the hydrogen contained in the fuel, by the oxygen of the air. After few seconds, this release stops. The calcined final product is white for three samples relating to three metals studied, although for the case of copper, the sample was blue. In order to identify the phases obtained, the products

At high temperature, the predominant phase is the calcite phase, this remark is recorded for three metals. The calcination gave rise to a new phase, which is only the metal oxide phase. The appearance of the PbO, CdO, and CuO oxide phases relating to the cure loaded, respectively by Pb, Cd, and Cu. The metal ions are finally recovered in the form of an oxide that can be used as a raw material in the field of

An adsorbent is of real interest only if it can be easily regenerated. The raw chitin used in the retention of metals must recover its initial structure and its starting chemical composition for a possible reuse with an appreciable re-adsorption

In most of the regeneration studies carried out on organic materials, the essential

heavy metals from seawater, these metals are then recovered by appropriate washing with an acid. Huang [44, 45] studied the regeneration of fungi biomass loaded by Cd2 +, and found that these materials can be regenerated by strong acids. Hoshi [33] exploited chitin in the determination of copper by column adsorption-elution, Cu2+ retained was eluted with a mixture of acetic acid and acetone. Roy [22] showed that most heavy metals can be recovered by lowering the pH of the medium, using an acid wash. In general, the efficiency of the regeneration depends on the rate of passage on the adsorbent, the direction of this passage, and the amount of the regenerating solution which is passed over the adsorbent. According to our study, it turns out that

. So, Muzzarelli [34] has exploited chitin to collect

resulting from the calcination were characterized by X-ray diffraction.

• The second is the recovery of this sludge by trying to study the regeneration

*DOI: http://dx.doi.org/10.5772/intechopen.88998*

ture is sufficient.

solid materials.

efficiency.

**9.2 Test of the chitin regeneration**

element used as regenerant is the H+

of the adsorbent support by an acid.

**9.1 Examination test for sludge generated by incineration**


## **9.1 Examination test for sludge generated by incineration**

Incineration can greatly reduce the volume and weight of household waste by transforming it into gas, heat, and sterile and inert materials, ashes and slag. Volume and weight reductions can 90 and 60%, respectively of the initial volume and weight of the garbage. The gases formed contain mainly excess air, water vapor, carbon dioxide (CO2), nitrogen oxides (NO×) fly ash, and in small quantities, various products from combustion: carbon monoxide (CO), organic matter, sulfur dioxide (SO2), hydrochloric acid, etc. The incineration takes place in three phases to know: drying with evaporation of water, spraying materials organics from 200°C and gasification of combustion of the carbonaceous residue: the volatile substances emitted burn at 500°C, this combustion is considered complete at 1000°C, provided that the air/fuel contact is satisfactory and the residence time at this high temperature is sufficient.

After the adsorption tests, the precipitates obtained loaded with the heavy metals are dried at 200°C in an oven and then calcined at high temperature (800°C) using a tubular oven for 2 hours, at the entry of the sample, the release of C, CO2, and H2O. Generally, when burning a conventional hydrocarbon fuel, one obtains at the end of the combustion, two harmless products CO2 and H2O, which result from the complete oxidation of the carbon and the hydrogen contained in the fuel, by the oxygen of the air. After few seconds, this release stops. The calcined final product is white for three samples relating to three metals studied, although for the case of copper, the sample was blue. In order to identify the phases obtained, the products resulting from the calcination were characterized by X-ray diffraction.

At high temperature, the predominant phase is the calcite phase, this remark is recorded for three metals. The calcination gave rise to a new phase, which is only the metal oxide phase. The appearance of the PbO, CdO, and CuO oxide phases relating to the cure loaded, respectively by Pb, Cd, and Cu. The metal ions are finally recovered in the form of an oxide that can be used as a raw material in the field of solid materials.

#### **9.2 Test of the chitin regeneration**

An adsorbent is of real interest only if it can be easily regenerated. The raw chitin used in the retention of metals must recover its initial structure and its starting chemical composition for a possible reuse with an appreciable re-adsorption efficiency.

In most of the regeneration studies carried out on organic materials, the essential element used as regenerant is the H+ . So, Muzzarelli [34] has exploited chitin to collect heavy metals from seawater, these metals are then recovered by appropriate washing with an acid. Huang [44, 45] studied the regeneration of fungi biomass loaded by Cd2 +, and found that these materials can be regenerated by strong acids. Hoshi [33] exploited chitin in the determination of copper by column adsorption-elution, Cu2+ retained was eluted with a mixture of acetic acid and acetone. Roy [22] showed that most heavy metals can be recovered by lowering the pH of the medium, using an acid wash. In general, the efficiency of the regeneration depends on the rate of passage on the adsorbent, the direction of this passage, and the amount of the regenerating solution which is passed over the adsorbent. According to our study, it turns out that

*Trace Metals in the Environment - New Approaches and Recent Advances*

In the case of Cd after the fourth test, the Cd ion content is below the FAO standard. In the case of Cu, the concentration ranges from 100 to 0.780 mg/l after third test and from 0.780 to 0.151 mg/l, after the fourth test, the equilibrium concentra-

First treatment 99.97 77.66 76.95 68.52 Fourth treatment 99.99 99.98 99.84 99.27 Simple treatment 99.54 98.22 98.74 96.14

*Values of equilibrium concentration in mg/l of metal ions after single treatment and after each test during* 

Co (mg/l) 100 100 100 100 Simple treatment 0.300 1.780 1.260 3.860 First trial 0.032 22.340 23.050 31.480 Second trial 0.002 11.400 0.824 2.489 Third trial 0.001 0.465 0.780 0.915 Fourth trial — 0.019 0.151 0.728 FAO (mg/l) 0.05 0.02 0.2 5 PVL (mg/l) 0.5 0.2 0.5 5

**Pb2+ Cd2+ Cu2+ Zn2+**

**Pb2+ Cd2+ Cu2+ Zn2+**

Finally, in the case of Zn2+, only two adsorption tests are required to reach the FAO standard of 5 mg/l, which is relatively higher than the standards for other met-

After a simple treatment, using the same quantity of the adsorbent used in the series treatment, it is noted that the quantities of metal ions remaining at equilibrium are greater than those remaining after the fourth serial treatment test; this

In **Table 11**, we calculated the percentage of abatement after the first test, the

According to this table, the series treatment is very effective to reduce the amount of metal ions and thus increase the reduction efficiency. For example, for Zn, we go from a percentage of 68.52% after the first test and 99.27% after fourth

**9. Sludge management test generated from the adsorption of heavy** 

One of the problems of the environment is the accumulation of solid waste. In order not to generate a simple transfer of pollution and in order to valorize the proposed treatment process, the solid sludge component generated by this treatment process "raw chitin saturated with heavy metals" should not weigh down the pollutant mass of household waste. From then we proposed at the end of this

tion is therefore lower than the FAO standard for Cu2+.

*Percentages of reduction of metals according to the number of tests.*

chapter two solutions to get rid of the generated sludge:

fourth trial, and simple treatment.

adsorption test.

**Table 11.**

**Table 10.**

*serial treatment.*

**metals**

als given the biological role played by Zn2+ in living organisms.

shows that serial processing is more effective than simple treatment.

**254**


#### **Table 12.**

*Variation of the release percentage according to the nature of the metal.*

the raw chitin has undeniable qualities of fixing heavy metals. For the regeneration tests, we chose the raw chitin of shrimp origin. Finally, the regeneration is carried out by HCl and focused on four metals, the regeneration conditions are optimized.

Let the percentage of release defined as following Eq. (3):

$$\text{\textquotedblleft off \textquotedblright release} = \mathsf{C}\_{\text{(metal)}} / \mathsf{C}\_{\text{M2} \text{\textquotedblright} \text{fixed}}\tag{3}$$

with

CM2+ fixed: concentration of M2+ fixed on the adsorbent before regeneration, C(metal): concentration of the released amount of M2+ after regeneration. Concentration CM2+ fixed is calculated according to the following Eq. (4):

$$\mathbf{C\_{M2}}\_{\*\text{fixed}} = \left[ \left( \mathbf{C} \mathbf{i} \mathbf{i} \mathbf{i} \mathbf{i} - \mathbf{C} \mathbf{e} \mathbf{l} \mathbf{r} \right) \mathbf{M} \mathbf{s} \right] / \mathbf{M} \mathbf{o} \mathbf{l} \mathbf{r} \tag{4}$$

#### with

Mo: initial mass before treatment; Ms: mass saturated with heavy metals; Vi: volume used for saturation; Vr: volume used for regeneration; Ci: initial concentration of metals; Ce: concentration of ions at equilibrium.

The amount released by HCl remains relatively stable from a concentration of 0.08 mol/l HCl, if we increase the concentration of HCl. It should be noted that all the metals studied are easily displaced by a low concentration of H, this shows that the interactions established between the metals and the raw chitin are not strong to resist the H+ ions. The released quantity is maximum in the case of Pb. In the case of Cu and Cd, it is almost constant and neighbor. These results are grouped in **Table 12**, indeed the percentages of release are equal.

#### **9.3 Comparison between the two processes and interpretation of results**

The incineration of raw chitin has led to metal oxides that can be recycled in other industries; in addition, it is a fast and perfectly hygienic process. It allows a significant reduction of waste in weight and volume. Therefore, it is the best solution in the case of effluents less loaded with heavy metals and whose composition is complex. However, the regeneration of raw chitin is a cumbersome process that requires the addition of reagents (acid, salt), and the use of material, in addition, it modifies the structure of the material, but in spite of this, the regeneration is the best solution in the case of mineral effluents heavily loaded with heavy metals and whose composition is simple.

### **10. Conclusion**

The isothermal study and kinetics of adsorption of metal ions on crude chitin has shown that the adsorption capacity of a metal depends on the origin of the latter

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*Sustainable Treatment of Heavy Metals by Adsorption on Raw Chitin/Chitosan*

and that the adsorption process is relatively fast. The Freundlich model is perfectly applicable; in fact, the correlation coefficients obtained for the four metal ions are very satisfactory. The removal efficiency of the metal ions depends on the initial concentration. This yield is high for a low initial concentration; therefore, the treat-

The comparative study with activated carbon (CAP) showed us that the raw chitin has a greater power of elimination than the (CAP), which suggests a probable substitution of CAP by chitin. According to this study, it can also be seen that the high temperature incineration of sludge generated by the adsorption of heavy metals on crude chitin results in calcite phases, which do not represent any toxicity in the environment and at low levels of metal oxide phases that can be recycled in the industry of solid materials (ceramics, cement, etc.). However, the regeneration of crude chitin changes the structure of the material relatively well and gives new

In summary, it can be argued that all the results obtained show the good ability of crude chitin to remove heavy metals when working under adequate conditions. Thus, fisheries waste, rich in chitin, would therefore constitute materials that could, on the one hand, eliminate metal pollutants, especially Pb2 +, Cd2+, Cu2+, and Zn2+ ions and on the other hand to substitute activated carbon in metal pollution

ment of metal pollution after dilution in industrial effluents is interesting.

*DOI: http://dx.doi.org/10.5772/intechopen.88998*

adsorbent supports.

treatment facilities.

**Author details**

Boukhlifi Fatima

Faculty of Science, MY Ismail University, Meknes, Morocco

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

\*Address all correspondence to: boukhlifi1@yahoo.fr

provided the original work is properly cited.

*Sustainable Treatment of Heavy Metals by Adsorption on Raw Chitin/Chitosan DOI: http://dx.doi.org/10.5772/intechopen.88998*

and that the adsorption process is relatively fast. The Freundlich model is perfectly applicable; in fact, the correlation coefficients obtained for the four metal ions are very satisfactory. The removal efficiency of the metal ions depends on the initial concentration. This yield is high for a low initial concentration; therefore, the treatment of metal pollution after dilution in industrial effluents is interesting.

The comparative study with activated carbon (CAP) showed us that the raw chitin has a greater power of elimination than the (CAP), which suggests a probable substitution of CAP by chitin. According to this study, it can also be seen that the high temperature incineration of sludge generated by the adsorption of heavy metals on crude chitin results in calcite phases, which do not represent any toxicity in the environment and at low levels of metal oxide phases that can be recycled in the industry of solid materials (ceramics, cement, etc.). However, the regeneration of crude chitin changes the structure of the material relatively well and gives new adsorbent supports.

In summary, it can be argued that all the results obtained show the good ability of crude chitin to remove heavy metals when working under adequate conditions. Thus, fisheries waste, rich in chitin, would therefore constitute materials that could, on the one hand, eliminate metal pollutants, especially Pb2 +, Cd2+, Cu2+, and Zn2+ ions and on the other hand to substitute activated carbon in metal pollution treatment facilities.
