**4. Characterization and treatment of current rinsing by adsorption on raw chitin**

### **4.1 Physical-chemical characterization**

#### *4.1.1 Physical-chemical*

We have studied the characterization and the treatment of the rejects of the metallization baths of metals Cu, Zn, Cr and Ni. The physico-chemical rinses aware of four baths metallization (Cu, Zn, Cr and Ni) has been grouped by the following table:

pH: Because of degreasing, etching and galvanic deposition, we worked with solutions of different types of reactions. We have to avoid absolutely the training of the slightest traces of a solution in what is next. In addition, we must ensure that no residual solution in the emptiness or back of the room, because this residue would affect extremely, adversely the adhesion of a plating. According all to the possibilities the rinsing must be done in that is rinses current water which is characterized by a neutral pH, from **Table 6**, the recorded pH is more neutral. The pH of the rinsing current Cr is acidic. All rinses Cr acquire the characteristics of a flushing death. The same for the flushing power of Cu, since it works with an alkaline bath, the pH of the rinse is relatively high; it reached a maximum 8.33 for the collection of 11-9-08. In the case of current rinsing bath of Zn is acid so the pH values below 7. They reach 6.6 by the same observation was recorded in the case of power flushing Ni. Note that for the same type of rinsing, the pH does not change significantly from one chain to another.

CE: Electrical conductivity is the lowest recorded in the case of the Cu current rinsing, while the highest values are recorded for the zinc rinses (**Table 6**).

MES: rinses have higher levels of MES ranging from 162 to 740 mg/l respectively for Ni and Zn. MES in the rinses is much smaller than the global rejection [14]. The rinses of zinc are the most loaded (**Figures 5** and **6**).

DCO: Highest values of DCO are recorded in the case of rinsing the zinc in the chain II, while for the rinsing of Ni, Cu and Cr, they do not exceed by 400 mg/l, that value is less the limit values (PVL).

OD: it is large fluctuations, water bodies are generally well oxygenated (**Table 6**). Maximum values up to 17.8 mg/l are noted in the current Cu rinses. This contribution is due to the complete absence of a biological pollution in the rinse tanks. Besides all the settings in this collection are low, the DCO does not exceed 40 mg/l. For comparison the variation of average concentrations of these parameters depending on the type of metal rinsing are shown in **Figure 5** below.


#### **Table 6.**

*Quality physical-chemical of rinses for the treatment.*

#### **Figure 5.**

*Evolution of the physicochemical parameters pH, EC, MES, COD, DO according to the type of current rinsing [RC(Ni), RC (Zn), RC(Cu) and RC(Cr)].*

**117**

**Table 7.**

**Figure 6.**

*Average levels of metal ions in the rinse currents.*

*Characterization and Treatment of Real Wastewater from an Electroplating Company by Raw…*

In order to assess metal pollution, we tried to assay the ion currents located in

In the studied unit, the static rinse is used primarily to recover and recycle metal in the plating baths, but on the other hand, the current simple rinsing aims to clean the pieces. The determination of heavy metals in these rinses (**Table 7**) shows that the levels of metal ions are very high. They are generally higher than those found in the global rejection. Example, the levels of Cu2+ reach an average

In fact, some bath rinses as Ni and Cr are highly concentrated in the rinse tanks, there are many colored water after rinsing the metal: green for Ni, Cu and blue to yellow for Cr. These waters differ slightly from the dead rinses. These huge losses of metal ions are due to inadequate drainage time pieces and often exceeded the stage of rinsing death. For the case of Cu the maximum values are found in the flushing of the IV chain, while the levels of the chain I are relatively low, this is due to the

For the case of Ni the values fluctuate between 15 and 34 mg/l with an average of 24.51 mg/l. In the case of Zn, the maximum values are recorded in samples of 11-9

**Nickel Copper Chrome Zinc**

11/9 34.21(II) 296.5(IV) 211.7(II) 201.1(I) 15/9 29.31 (II) — 20.13(IV) 32.4(I) 23/9 19.02(II) 20.70 (I) — 41.6(I) 29/9 — — 0.96(II) — 3/10 15.05(II) 256.6(IV) — 670.1(I) 3/10 — 68.3(I) 188.6(IV) —

*Evolution of metal ion concentrations (mg/l) according to the type of rinsing in different chains.*

It should be noted also that in the current flush of a metal there are traces of other metals, rinsing the Ni the chain of 3-10 II also contains Cu and Zn, Cu rinsing

*DOI: http://dx.doi.org/10.5772/intechopen.89058*

the rinsing after plating by Cu, Zn, Cr and Ni (**Figure 6**).

number of work pieces and the capacity of each channel.

contains Cr, Cr rinse contains Ni and Cu (**Table 8**).

*4.1.2 Metal pollution*

22.21 mg/l [14].

and 3-10.

*Characterization and Treatment of Real Wastewater from an Electroplating Company by Raw… DOI: http://dx.doi.org/10.5772/intechopen.89058*

#### *4.1.2 Metal pollution*

*Recent Advancements in the Metallurgical Engineering and Electrodeposition*

**(mS/cm)**

**MES (mg/l)**

Ni2+ 15/9 II 6.81 3.66 162 — 16.6 348 537 —

Zn2+ 15/9 I 6.07 43.75 500 3920 6.41 556 — —

Cr6+ 15/9 IV 3.21 8.16 234 315 9.2 202 — —

Cu2+ 23/9 IV 7.51 2.13 138 40 17.8 37.9 239 192.1

*Evolution of the physicochemical parameters pH, EC, MES, COD, DO according to the type of current rinsing* 

**DCO (mg/l)**

11/9 II 6.96 3.93 190 380 14.6 212 — —

23/9 II 6.56 3.73 134 300 12 200 521 — 3/10 II 6.72 4.00 — 340 10.0 64.8 507 736.2 11/9 I 6.04 49.50 525 2960 4.9 631 — 688

23/9 I 6.04 63.79 740 2800 5 500 — 785.8 3/10 I 6.08 58.0 715 3760 6.6 424.8 724 883.4 11/9 II 3.02 3.93 492 258 10.2 — —

29/9 II 4.12 3.05 138 418 5 353 — — 3/10 IV 2.5 17. 5 74 269 121.4 50.4 — 272 11/9 II 8.33 3.04 88 480 8.5 — 597 112.1

3/10 I 8.19 2.24 628 400 12.01 13.9 269 160.0 3/10 I 7.97 3.74 190 240 14.7 — 726 288.1

**OD (mg/l)**

**SO42<sup>−</sup> (mg/l)**

**Cl- (mg/l)**

**Ca2+ (mg/l)**

**Chain pH CE** 

*Quality physical-chemical of rinses for the treatment.*

**Day/ month**

**Table 6.**

**116**

**Figure 5.**

*[RC(Ni), RC (Zn), RC(Cu) and RC(Cr)].*

In order to assess metal pollution, we tried to assay the ion currents located in the rinsing after plating by Cu, Zn, Cr and Ni (**Figure 6**).

In the studied unit, the static rinse is used primarily to recover and recycle metal in the plating baths, but on the other hand, the current simple rinsing aims to clean the pieces. The determination of heavy metals in these rinses (**Table 7**) shows that the levels of metal ions are very high. They are generally higher than those found in the global rejection. Example, the levels of Cu2+ reach an average 22.21 mg/l [14].

In fact, some bath rinses as Ni and Cr are highly concentrated in the rinse tanks, there are many colored water after rinsing the metal: green for Ni, Cu and blue to yellow for Cr. These waters differ slightly from the dead rinses. These huge losses of metal ions are due to inadequate drainage time pieces and often exceeded the stage of rinsing death. For the case of Cu the maximum values are found in the flushing of the IV chain, while the levels of the chain I are relatively low, this is due to the number of work pieces and the capacity of each channel.

For the case of Ni the values fluctuate between 15 and 34 mg/l with an average of 24.51 mg/l. In the case of Zn, the maximum values are recorded in samples of 11-9 and 3-10.

It should be noted also that in the current flush of a metal there are traces of other metals, rinsing the Ni the chain of 3-10 II also contains Cu and Zn, Cu rinsing contains Cr, Cr rinse contains Ni and Cu (**Table 8**).

**Figure 6.** *Average levels of metal ions in the rinse currents.*


**Table 7.**

*Evolution of metal ion concentrations (mg/l) according to the type of rinsing in different chains.*


**Table 8.**

*Concentration of metal ions in the rinse of metal in mg/l of sample 3/10.*

#### **4.2 Rinsing water treatment test common to plating baths**

The current water rinses are treated the same way that releases overall. We studied the case of Cu, Ni, Cr and Zn. For each metal we have tried to work on two different samples. The results of this study are summarized in the **Table 9** below.

The expression of the calculation of the % of adsorption is 100 \* C0-Ceq/C0.

Cu: The table shows that the removal efficiency increases as the mass of material increases especially for the rejection diluted. In general, treatment of rinse water is more effective than the treatment of Cu in the global rejection [6–8]. Indeed, the removal percentages do not exceed more than 63% in the global rejection while for flushing streams they reach 98.08%.

Ni: In the case of Ni, we see that the residual concentration decreased from 1.5 to 1.2 mg/l with a percentage reduction is very small compared to the percentage reductions in the case of total rejection [6], we can say that the presence of other metals does nothing, but increasing the removal of the Ni.

Cr: the removal yields is relatively low compared to those found in the overall rejection, it does not exceed 28% for the diluted rinsing and 25% for the concentrated rinsing.


#### **Table 9.**

*Changes in percentage of the adsorption of metal ions of the current rinses depending on the dose of added material.*

**119**

*Characterization and Treatment of Real Wastewater from an Electroplating Company by Raw…*

Zn: to achieve a removal efficiency of 90.23%, it is necessary to introduce a mass of 200 mg, Similar to Cu, the effect of the dose of the material added to the percentage reduction of micro metal is very pronounced for high concentrations of metals. This result confirms the results found by Boukhlifi et al. [17, 30, 31]. By comparing the removal efficiency of the four metals, it appears that the strongest removal is

A chain consists of a set of tanks whose general functions are: surface preparation, processing and finishing of the piece part in question. Each tank is defined by

• The mode of treatment (pretreatment, metal deposition, stripping ...)

• The type of chosen treatment (e.g. a metal deposit: silver, chrome plating,

• The operating conditions (for example, a zinc plating: alkaline non-cyanide, acid fluroborate not …) including different chemicals concentrations, fluid

The unit of surface treatment under study is composed of five chains. Each channel is determined by the succession of tanks. The average capacity of baths varies between 950 l and 1710 l, but most of the bath has a volume of 1440 l, the majority of the baths is powered water wells except metal plating baths and degreasing baths, which are filled with drinking water, bathing water that is recycled in metal plating baths of rinses dead. Water supply wells are often for an hour a day, while drinking water is draining after a bath. Discharges baths is collected through pipes that lead to the aerated sewage. All discharges are evacuated in the rough, but the rejection of the flushing stream which is recycled zinc. We were interested in flushing power of Ni and Cr; we followed up daily flow rates

We found that the high flow rates were recorded for Cr and Ni, the rate of flushing power of Cr can be up to 600 l/h and the neither flushing current reached a

• The flow rates of Ni in the chain will fluctuate between 260 and 390 l/h, they will reach 389.21 l/h, a value which represents the 1/3 of the bath of treatment, that is to say that every day, the third of the rinsing bath is changed with a capacity of 1440 l. This during the fifth of the rinsing bath of Cr is changed. These waters are evacuated; this appears from the color of releases. Rejection

The Ni current rinsing flow varies from one channel to another varies from the

• The temporal variation of the flow does not follow a given order; it varies from day to day depending on water supplies that are directly related to the availability of water in the well. - We tried to compare these rates with those of other baths as bath chemical degreasing and pickling bath. The flow of degreasing bath is lower and messy, while the stripping is relatively constant and is around 400 l/h.

of Cr is yellow while the rejection of Ni is green.

average flow 389 l/h for channel II 738.8 l/h for the string I.

*DOI: http://dx.doi.org/10.5772/intechopen.89058*

copper plating, zinc plating, etc.)

flow, the rate of production, etc.

of 7/9 to 3/10 in **Figures 7** and **8**.

maximum of 841 l/h.

marked for the case of Cu [16].

**5. Study flow of pollution**

three characteristics:

*Characterization and Treatment of Real Wastewater from an Electroplating Company by Raw… DOI: http://dx.doi.org/10.5772/intechopen.89058*

Zn: to achieve a removal efficiency of 90.23%, it is necessary to introduce a mass of 200 mg, Similar to Cu, the effect of the dose of the material added to the percentage reduction of micro metal is very pronounced for high concentrations of metals. This result confirms the results found by Boukhlifi et al. [17, 30, 31]. By comparing the removal efficiency of the four metals, it appears that the strongest removal is marked for the case of Cu [16].
