**2. Materials and methods**

*Recent Advancements in the Metallurgical Engineering and Electrodeposition*

tions in application [1].

in Taiwan and in South Korea [11, 12].

discharge principle [22, 23].

Different treatment techniques for wastewater laden with heavy metals have been developed in recent years both to decrease the amount of wastewater produced and to improve the quality of the treated effluent. Although various treatments such as chemical precipitation, coagulation-flocculation, flotation, ion exchange and membrane filtration can be employed to remove heavy metals from contaminated wastewater, they have their inherent advantages and limita-

Chemical precipitation is widely used for the treatment of electroplating wastewater [2, 3]. It consists of adding a base followed by sedimentation. The pH is adjusted to the minimum solubility, so it is difficult to treat multiple metals simultaneously. Coagulation-flocculation has also been employed for heavy metal removal from inorganic effluent [4]. Sorptive flotation has attracted interest in Greece and the USA [5–7] for the removal of non-surface active metal ions from contaminated wastewater. In recent years, ion exchange has also received considerable interest in Italy and Spain [8, 9] as one of the most promising methods to treat heavy metals. Starch xanthate (XA) synthetic polymers resins grafted cellulose natural zeolites are used. This process is particularly effective for the recovery of metals, but the cost of the process is very expensive and often justified only metals are recovered [10]. Due to its convenient operation, membrane separation has been increasingly used recently for the treatment of inorganic effluent. There are different types of membrane filtration such as ultrafiltration, nanofiltration and reverse osmosis. Membrane filtration has used

The adsorption treatment is widely used with activated carbons, this process has several advantages: it is very effective in removing heavy metals even at low pH [13] with different adsorbent materials such as polymers [14–16] and clays [17–19]. Electrolysis is generally used to treat water with high metal content. One of the major obstacles encountered in this technique is the complexity of the environments to be treated that leads to a series of redox reactions [20]. In recent year, the clean Technology constituted preventive actions to review and question the production concept, these actions converge to a common point: Targeting the pollution source rather than its reverse vector example osmosis [21] and zero

In general, control of water flow requires the establishment of means for counting and control flow at the entrance of each channel. In addition, it reduces the consumption of reagents and production of sludge treatment plant, which is a significant gain in operating costs. Several techniques exist to recover the flow

• The decrease in volumes trained by parts by adjusting the drainage time.

• The establishment of additional rinse tanks such as rinsing tank death after degreasing, pickling, hot metal deposition and passivation, it traps the metal salts which are then reassembled in the treatment bath to compensate for evaporation. Rinsing; in which the parts are dipped before and after the cold metal plating baths, it can recover from 30 to 50% of the entrained

• Finally, the development of production lines to reduce pollution is an opportunity to optimize production (questioning of manufacturing ranges, the products used and streamlining the flow of parts) and improves quality and

pollutants at the source to mention a few key principles:

**108**

flow.

working condition.

A study unit is MAFER located at CASABLANCA in MOROCCO. Its activity is surface treatment. The studied unit of surface treatment consists of five chains. Every chain is determined by the succession of tanks. The average capacity of baths varies between 950 and 1710 l. The majority of baths has a volume of 1440 l and is fed by well water except the bath of metallic deposit and the baths of rundown which are filled by the drinking water. Waters of the baths of the dead rinsing are recycled in the bath of metallic deposit. The water supply of well often matches 1 h a day. Whereas the drinkable water supply is made after draining of bath.

#### **2.1 Preparation of the adsorbent**

the shells of Shrimp (Ccre) and the shells of crabs (Ccra) are isolated at first by their mild part (protein) washed in bidistilled water then dried at 100°C during 48 h [17], then crushed and sieved. The size grading is understood between 100 and 125 μm.

#### **2.2 Adsorption test**

A mass of the adsorbent is placed in contact with the rejection to be treated (100 ml). The suspensions were stirred (500 rev/min) in constant temperature (25 ± 2°C) until adsorption equilibrium obtained for a duration of 4 h [17]. The supernatant is filtered and the equilibrium concentration (Ceq) is determined after mineralization by flame atomic absorption using a Philips type PU 900.

\*Physico-chemical analysis of the rejection quality:

PH: Measured using a pH meter ORION RESEARCH type and a combined glass electrode.

Electrical conductivity (CE): measured using a conductivity type ORION RESEARCH mod 101 and a 1 cm cell.

Chemical oxygen demand (DCO): Determined according to AFNOR T90-101. The principle consists in oxidizing the organic matter contained in wastewater by an excess of silver sulfate.

Suspended solids (MES): Determined according to standard AFNOR T90-105, the filtering is done on Whatman paper (0.45 mm). The drying of the already weighed filter is done at 105°C for 1 h and weighed.

Dissolved oxygen (OD): Determined using a pulse oximeter, the assay is performed directly by immersing the electrodes in water for analysis. The oxygen reduction at the cathode generates a proportional current to the partial pressure of oxygen in the cell.
