How to Reduce Ammonia in Water

Introduction

Ammonia is a prevalent contaminant in wastewater, often arising from agricultural runoff, industrial discharges, and sewage. Elevated levels of ammonia can be toxic to aquatic life and pose significant environmental and public health risks. Therefore, it is imperative to reduce ammonia concentrations in wastewater to meet regulatory standards and protect the environment. This guide delves into various effective methods for reducing ammonia in wastewater, complemented by a detailed case study illustrating a successful ammonia reduction project at a rendering facility.

Understanding the Impact of Ammonia in Wastewater

Ammonia, a nitrogenous compound, can lead to several environmental issues if not properly managed:

• Eutrophication: Ammonia contributes to nutrient overload in water bodies, leading to excessive growth of algae and aquatic plants. This process, known as eutrophication, depletes oxygen in the water, harming aquatic life.
• Toxicity: High levels of ammonia are directly toxic to fish and other aquatic organisms. Ammonia interferes with the ability of aquatic animals to excrete nitrogenous wastes, leading to harmful physiological effects.
• Human Health Risks: Ammonia can contaminate drinking water sources, posing health risks to humans, including respiratory issues and other health complications.

Methods to Reduce Ammonia in Wastewater

Biological Treatment Processes

a. Nitrification and Denitrification

• Nitrification: This biological process converts ammonia (NH3) into nitrite (NO2-) and then nitrate (NO3-) through the action of nitrifying bacteria such as Nitrosomonas and Nitrobacter. This process requires aerobic conditions and is commonly employed in wastewater treatment plants.
• Denitrification: In this subsequent process, denitrifying bacteria convert nitrate into nitrogen gas (N2), which is then released into the atmosphere. Denitrification occurs under anoxic conditions and is essential for complete nitrogen removal from wastewater.

b. Moving Bed Biofilm Reactor (MBBR)

• MBBR is an advanced biological treatment process that uses suspended plastic carriers within a reactor to support biofilm growth. These biofilms degrade organic matter and ammonia, converting them into less harmful substances. MBBR systems are highly efficient, space-saving, and require minimal maintenance compared to traditional biological treatment methods.

c. Sequencing Batch Reactor (SBR)

• SBR is a type of activated sludge process where wastewater treatment occurs in batch mode. This method allows for the control of different treatment phases (aeration, settling, and decanting) within a single reactor, facilitating efficient ammonia removal through nitrification and denitrification.

Chemical Treatment Processes

a. Breakpoint Chlorination

• This chemical process involves adding chlorine to wastewater to oxidize ammonia, forming nitrogen gas and other byproducts. The process requires precise control of chlorine dosage to achieve the "breakpoint" where ammonia is effectively removed without leaving excess chlorine in the effluent, which can be harmful to aquatic life.

b. Ion Exchange

• Ion exchange is a process that uses specialized resins to remove ammonia ions from wastewater. The resins exchange ammonium ions (NH4+) with other ions (such as sodium or hydrogen) in the resin. Once the resin is saturated with ammonium ions, it can be regenerated with a strong brine solution, making this a cost-effective method for small to medium-scale applications.

c. Chemical Precipitation

• Chemical precipitation involves adding chemicals such as lime or magnesium to wastewater to form insoluble compounds with ammonia, which can then be removed through sedimentation or filtration. This method is effective for reducing high ammonia concentrations but requires careful management of chemical dosages and byproducts.

Physical Treatment Processes

a. Air Stripping

• Air stripping is a process where air is blown through wastewater to volatilize and remove ammonia. This method is particularly effective for wastewater with high pH levels, as ammonia is more volatile in alkaline conditions. Air stripping towers or packed columns are commonly used for this purpose.

b. Membrane Filtration

• Membrane filtration techniques, such as reverse osmosis (RO) and nanofiltration (NF), can effectively remove ammonia from wastewater. These processes use semi-permeable membranes to separate ammonia and other contaminants from the water, producing high-quality effluent. However, membrane systems require regular maintenance and can be energy-intensive.

Case Study: Reducing Ammonia in a Rendering Facility

The Problem

A rendering facility encountered a significant issue when its existing Rotating Biological Contactor (RBC) system failed due to a rotating assembly bearing and shaft failure. This failure resulted in the overloading of the existing lagoons with ammonia from the anaerobic treatment process, leading to non-compliance with discharge regulations and environmental concerns.

bioprocessH2O's Solution

To address this critical problem, bioprocessH2O was selected to provide an advanced bioFAS™ Moving Bed Biofilm Reactor (MBBR) System equipment package. This system was designed to retrofit and upgrade the existing RBC basins into a two-stage bioFAS™ MBBR process, aimed at reducing Biochemical Oxygen Demand (BOD5) and nitrifying ammonia.

Phase 1: Emergency Retrofit

• The first phase of the project involved an emergency response to retrofit the existing RBC basin within four weeks and have the system operational. This rapid deployment was crucial to mitigate the ammonia overload and restore compliance with discharge regulations.

Phase 2: Automation and Optimization

• In the second phase, bioprocessH2O supplied a fully automated electrical control panel equipped with a Programmable Logic Controller (PLC), Variable Frequency Drives (VFD) for the blowers, and a set of automated control valves and dissolved oxygen (DO) sensors. This setup enabled an automated DO control system, optimizing the nitrification process and enhancing system performance.

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Status/Results

• Within 7 days of operation, the bioFAS™ MBBR system successfully nitrified ammonia, removing 120 lbs NH4 per day. This rapid response demonstrated the system's efficiency and effectiveness in treating high ammonia loads.
• After 14 days, the nitrification rate increased to 160 lbs NH4 per day, further validating the robustness of the bioFAS™ MBBR system.
• At a current flow rate of 43,500 gallons per day (GPD), the bioFAS™ MBBR System consistently meets and exceeds all expectations of the nitrifying biological treatment process, ensuring regulatory compliance and environmental protection.

Conclusion

Reducing ammonia in wastewater is essential for safeguarding aquatic ecosystems and meeting environmental regulations. Biological treatment methods such as MBBR and SBR, chemical treatments like breakpoint chlorination and ion exchange, and physical processes like air stripping and membrane filtration offer effective solutions for ammonia removal. The case study of bioprocessH2O’s bioFAS™ MBBR system in a rendering facility exemplifies the successful application of advanced biological treatment processes, highlighting their efficiency and reliability.

For tailored solutions to your ammonia reduction challenges, call and speak with one of our engineers today to maximize the performance of your water treatment systems

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