How to Solve Long-Term Total Nitrogen Exceedance in Fertilizer Wastewater Treatment?

11 May, 2026 5:14pm

In the fertilizer industry, wastewater generated from ammonia production, phosphate fertilizer processing, and compound fertilizer manufacturing is one of the most challenging industrial effluents to treat. Among all pollutants, total nitrogen (TN) exceedance remains the most persistent compliance issue.

Total nitrogen includes multiple nitrogen forms such as organic nitrogen, ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen. If any of these are not properly removed, the final effluent will exceed discharge standards, leading to environmental penalties, production restrictions, and operational risks.

This article explains the root causes of TN exceedance and how WTEYA provides a full-process solution to solve it effectively and sustainably.

1. Why Total Nitrogen Remains Difficult to Control in Fertilizer Wastewater

1.1 Complex wastewater composition

Fertilizer wastewater is highly complex, typically containing:

• High ammonia nitrogen (2000–5000 mg/L, sometimes exceeding 10,000 mg/L)

• Organic nitrogen and nitrate compounds

• High salinity wastewater

• Refractory organic additives

• Occasional heavy metal residues

A single treatment method cannot effectively remove all nitrogen forms, leading to unstable TN performance.

1.2 Failure of biological nitrogen removal systems

The nitrification–denitrification process is easily disrupted:

High salinity and toxic compounds inhibit nitrifying bacteria

• Low C/N ratio leads to insufficient carbon source for denitrification

• Dissolved oxygen imbalance affects anaerobic and anoxic zones

• Unstable internal recycle reduces nitrate conversion efficiency

As a result, nitrogen accumulates in different forms and causes continuous exceedance.

1.3 Strong fluctuations in wastewater load

Fertilizer production is not stable:

• Seasonal fertilizer demand increases wastewater volume significantly

• Equipment cleaning cycles generate shock loads

• Production switching causes sudden chloride and nitrogen concentration spikes

Traditional systems without buffering capacity cannot handle such fluctuations, resulting in system collapse or performance decline.

1.4 Poor process design and operation management

Many plants still rely on simplified systems due to cost constraints:

• Lack of pretreatment for refractory nitrogen

• Improper carbon dosing

• Incorrect sludge age control

• Equipment scaling and clogging issues

• Manual operation without real-time control

Industry data shows that over 60% of TN exceedance cases are directly linked to system design and operation issues.

2. WTEYA Full-Process Solution for Total Nitrogen Removal

To address these challenges, WTEYA adopts a full-process integrated treatment strategy:

Pretreatment → Core Nitrogen Removal → Advanced Polishing → Smart Operation Control

This system is customized for different fertilizer wastewater types, including ammonia fertilizer, phosphate fertilizer, and compound fertilizer industries.

3. Step 1: Pretreatment for Load Reduction and Stability

Pretreatment is critical for system stability and downstream biological efficiency.

WTEYA’s pretreatment includes:

• Chemical breaking agents to destroy complex nitrogen bonds

• pH adjustment for optimal biological conditions

• Air stripping or steam stripping for high ammonia removal

• Acid absorption system to recover ammonia as ammonium sulfate

• Hydrolysis acidification to improve biodegradability

• Coagulation and sedimentation to remove suspended solids

• Equalization tank to buffer hydraulic and load fluctuations

• Ammonia removal efficiency can reach 80%–95%, significantly reducing system load.

4. Step 2: Core Biological Nitrogen Removal Enhancement

WTEYA enhances nitrification and denitrification efficiency through optimized biological systems:

• Improved A²/O + shortcut nitrification-denitrification process

• MBR (Membrane Bioreactor) for higher biomass concentration

• Intelligent carbon dosing system based on real-time C/N ratio

• Dissolved oxygen control in anoxic zones (<0.5 mg/L)

• Optimized internal recycle ratio for nitrate reduction

• Specialized microbial inoculation for high-salinity environments

• Anammox process for low-carbon wastewater, reducing energy and chemical use

This stage significantly improves nitrogen conversion efficiency and system stability.

5. Step 3: Advanced Polishing to Prevent Rebound

To ensure stable discharge compliance, WTEYA applies advanced polishing technologies:

• Advanced oxidation (Fenton, ozone) to degrade refractory nitrogen compounds

• Nanofiltration and reverse osmosis for deep nitrogen removal and water reuse

• Multi-effect evaporation for salt and ammonium sulfate recovery

• Breakpoint chlorination for residual ammonia removal

• Activated carbon adsorption for trace organic nitrogen and color removal

These processes ensure stable TN compliance and enable near-zero discharge when required.

6. Step 4: Smart Operation and Cost Control System

WTEYA integrates full automation and intelligent control systems:

• PLC/DCS centralized monitoring system

• Real-time monitoring of TN, DO, pH, sludge concentration

• Automatic chemical dosing adjustment

• Intelligent aeration and recycle control

• Fault early-warning system

• Anti-scaling and anti-clogging equipment design

• Remote monitoring and technical optimization support

This significantly reduces manual operation and overall operating costs.

Conclusion:

Long-term total nitrogen exceedance in fertilizer wastewater is caused by complex wastewater composition, unstable biological systems, and insufficient process design.

Only a full-process, integrated, and intelligent treatment system can solve the problem fundamentally.

With advanced engineering experience and customized solutions, WTEYA helps fertilizer enterprises achieve stable compliance, cost reduction, and sustainable green development.