Heavy metals and adsorbents effects on activated sludge microorganisms

Area of Science:

• Environmental Science
• Water Treatment
• Adsorption Technology

Background:

• Heavy metal contamination in water poses significant environmental and health risks.
• Developing efficient and cost-effective adsorbents for metal removal is crucial for water remediation.
• Understanding the impact of adsorbents on biological wastewater treatment processes is essential.

Purpose of the Study:

• To investigate the sorption of Cu(II) and Cd(II) using powdered activated carbon (PAC), biomass, rice husk (RH), and activated rice husk (ARH).
• To evaluate the adsorption capacities of different adsorbents based on Langmuir isotherm parameters.
• To assess the effect of these adsorbents on the specific oxygen uptake rate (SOUR) of activated sludge microorganisms in the presence of heavy metals.

Main Methods:

• Batch experiments were conducted to study the sorption of Cu(II) and Cd(II).
• Rice husk (RH) was activated using concentrated nitric acid at 60-65°C for 15 hours.
• Adsorption capacities were determined using the Langmuir isotherm model, and SOUR was measured for activated sludge.

Main Results:

• The order of increasing adsorption capacities (Langmuir Q° parameter) was biomass > PAC > ARH > RH.
• Activation of rice husk with nitric acid significantly increased its adsorption capacity.
• Addition of adsorbents enhanced the SOUR of activated sludge, mitigating the inhibitory effects of Cu(II) and Cd(II).

Conclusions:

• Biomass, PAC, ARH, and RH are effective adsorbents for removing Cu(II) and Cd(II) from synthetic solutions.
• Activated rice husk shows improved adsorption performance compared to raw rice husk.
• PAC and RH can reduce the inhibitory impact of heavy metals on activated sludge microorganisms, potentially improving biological wastewater treatment efficiency.