A review of integrated control of volatile fatty acids and downstream nitrogen removal during anaerobic treatment of pharmaceutical wastewater: carbon-nitrogen-sulfur interactions and process optimization.

A process-oriented C-N-S framework for high-strength pharmaceutical wastewater links VFA accumulation, ammonium release, and sulfur transformation to nitrogen-removal performance, enabling targeted control and post-anaerobic selection.

• Why it matters: Anaerobic mineralization in pharmaceutical wastewater continuously generates VFAs and ammonia, while pH, alkalinity, free ammonia, salinity, sulfide, electron-donor competition, and toxicity can destabilize reactors and reduce nitrogen removal efficiency.
• What they did: The study evaluates inhibitory effects of VFA buildup, ammonium release, and sulfur transformation, then uses a step-by-step selection approach to match post-anaerobic nitrogen removal to inhibitor presence, nitrogen species, electron acceptor supply, alkalinity balance, and carbon reserves.
• The result: It identifies PN/A as suitable for ammonium-rich wastewater with low biodegradable carbon and acceptable toxicity, PD/A as requiring stable nitrate and adjustable VFA supply, and sulfur-driven partial denitrification as producing nitrite when sulfide stays below the inhibition threshold.

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