Match each specific industrial effluent contaminant listed on the left with its standard c… — JAMB UTME

Match each specific industrial effluent contaminant listed on the left with its standard chemical treatment or remediation technique on the right.

Dissolved toxic heavy metal ions such as $Pb^{2+}$ and $Cd^{2+}$ from battery manufacturing plantsPrecipitation as insoluble hydroxides or sulfides using calcium hydroxide, $Ca(OH)_2$ , or sodium sulfide, $Na_2S$
Non-biodegradable synthetic organic dyes from textile factory wastewaterAdsorption onto high-surface-area activated granular carbon beds
Phosphate-rich surfactants ( $PO_4^{3-}$ ) from industrial laundry detergentsChemical precipitation using alum or lime followed by tertiary biological nutrient removal to prevent eutrophication
Acidic effluent containing dissolved $H_2SO_4$ from metal-pickling and mining processesNeutralization reaction using limestone, $CaCO_3$ , or slaked lime to restore neutral $\text{pH}$

Answer

Heavy metal ions (

Pb^{2+}, Cd^{2+}

) pair with precipitation using

Ca(OH)_2

Na_2S

; non-biodegradable synthetic dyes pair with activated carbon adsorption; phosphate surfactants pair with precipitation and biological nutrient removal; and acidic effluent (

H_2SO_4

) pairs with lime/limestone neutralization.

Each industrial pollutant is matched to its chemically specific treatment based on functional chemistry: heavy metal ions precipitate as sulfides/hydroxides, non-biodegradable organic dyes adsorb onto activated carbon, phosphates precipitate to control eutrophication, and acidic effluents are neutralized with basic compounds.

Step-by-Step Solution

Analyze heavy metal waste remediation chemistry

Heavy metal cations (

Pb^{2+}, Cd^{2+}

) react with

OH^-

S^{2-}

to form insoluble salts (

PbS

Cd(OH)_2

) precipitating out of solution.

Chemical precipitation renders toxic soluble metals insoluble and separable by filtration.

Evaluate textile dye removal processes

Refractory organic dye molecules adsorb onto activated carbon porous structures.

Synthetic organic dyes are resistant to standard oxidation/biodegradation but adsorb readily onto carbon surfaces.

Identify phosphate pollution control

Phosphates precipitate as calcium phosphate or aluminum phosphate during tertiary wastewater treatment.

Phosphate removal is critical to prevent algal blooms and eutrophication in receiving aquatic ecosystems.

Determine acidic wastewater treatment

H_2SO_4

reacts with

CaCO_3

Ca(OH)_2

in an acid-base neutralization producing neutral sulfate salts and water.

Adjusting effluent

\text{pH}

to near neutral (

6.5-8.5

) is mandatory prior to discharge to safeguard aquatic life.

Key Concept

Industrial Effluents and Specific Water Remediation Techniques

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