LAR NitriTox Online Toxicity Analyzer

Overview

The LAR NitriTox is an online toximeter that protects the biological stage of wastewater treatment plants. Developed by LAR Process Analysers and supplied today under the Process Insights group, it continuously tests incoming water for substances that inhibit nitrifying bacteria, the sensitive organisms that oxidize ammonium to nitrate. Measurements follow in short intervals, with a response time as low as 5 to 10 minutes depending on the application, giving operators time to divert or buffer a toxic load before it damages the treatment process.

Seven Star LLC supplies the LAR NitriTox to industrial and municipal wastewater operators in Oman and the GCC, including refinery and petrochemical effluent plants and treatment works that receive mixed industrial discharges. From Muscat we supply consumables on request and provide engineering support for application review, installation planning and commissioning.

Measurement Principle

The LAR NitriTox determines toxicity by measuring the oxygen conversion of nitrifying bacteria, in line with DIN EN ISO 9509:2006, which describes a toxicity test based on the inhibition of nitrification. In general, healthy nitrifiers consume oxygen at a predictable rate when fed ammonium; if a sample contains inhibiting substances such as heavy metals, solvents, cyanides or certain biocides, respiration slows. By comparing the respiration of bacteria exposed to the sample with a reference, the analyzer reports inhibition on a scale from 0 to 100% toxicity.

A key design point is the self-regenerating bacteria culture. The LAR NitriTox contains an integrated fermenter which constantly and independently produces fresh biomass, so there is always enough bacteria for each new measurement. Because every sample is tested with a fresh portion of bacteria, the culture in the fermenter is not contaminated by a toxic sample, and a toxic event can be followed from start to finish. No test organisms need to be purchased, which keeps running costs low.

Engineering Design of the LAR NitriTox

The analyzer is built in a powder-coated steel cabinet rated IP54, measuring W 630 x H 1,265 x D 580 mm and weighing approximately 70 kg. The upper section carries a 10.4 in back-lit TFT touch screen with self-explanatory software, a service checklist and an autostart function; the lower section houses the fermenter, measuring cell, pumps and hydraulics. Sample inflow and outflow use 6 mm and 8 mm ID tubing, and soft particles up to 2 mm are acceptable. A FlowSampler sample taking system and air treatment are available as options.

Power is 230 or 115 V AC at 50 or 60 Hz and 100 VA, with 10 A internal and 16 A external protection. Data output includes 0/4-20 mA analog signals, an RS 232 interface, combined alarms, life-zero signalling and USB, plus optional remote control over TCP/IP. The permissible sample temperature is 5 to 25 °C and the recommended ambient temperature 10 to 25 °C at up to 80% humidity, so in the GCC the LAR NitriTox is normally installed in a conditioned analyzer house, with sample cooling where needed. Planning the sample line, drain and shelter layout early in a project avoids most later commissioning problems.

In general, nitrification is the slowest and most fragile step of biological treatment: nitrifiers grow slowly, so a single toxic shock can take days or weeks to recover from, during which ammonium passes through to the effluent and discharge limits are exceeded. That is why plants receiving industrial wastewater often place a toximeter ahead of the aeration tanks. Alarm thresholds on the LAR NitriTox are set by the operator, and the analog and alarm outputs can trigger valves or pumps that route suspect water to an emergency basin automatically.

Key Features

Features that make the LAR NitriTox effective:

• Continuous toxicity monitoring with a range of 0 to 100% toxicity.
• Response time as fast as 5 to 10 minutes, application dependent, with a cycle time of 12 to 15 minutes.
• A self-regenerating culture of nitrifying bacteria that removes the need to buy test organisms.
• Fresh biomass for every test, so the fermenter is protected from contamination.
• High sensitivity to a variety of pollutants that inhibit nitrification.
• Measurement according to DIN EN ISO 9509:2006.
• A 10.4 in touch screen with autostart and a built-in service checklist.
• Analog, serial, alarm and USB outputs for integration with plant control systems.

Industrial Applications

Process Insights lists water influent, industrial wastewater and wastewater treatment plants as the main applications of the LAR NitriTox. The typical position is at the inlet of a biological plant, where it acts as an early warning system: when inhibition rises, the plant can divert the flow to a holding basin, increase dilution or alert upstream dischargers. In Oman this is relevant for industrial effluent plants in Sohar Freezone and the Duqm Special Economic Zone, for refinery and petrochemical biological treatment, and for municipal plants in Muscat that receive tanker discharges and industrial connections.

Seven Star LLC supplies the LAR NitriTox with consumables and service support, and offers complementary LAR analyzers for organic load measurement. On this site you can find the LAR 501-40-000215 peristaltic pump as a LAR spare part, the Hach BioTector B3500ul online TOC analyzer for organic carbon and the AppliTek TOPHO on-line total phosphorous analyzer for nutrient monitoring.

Technical Specifications

The LAR NitriTox data below comes from the Process Insights NitriTox datasheet, rev. 23.1:

How to Order

To quote the LAR NitriTox, send Seven Star LLC a description of the wastewater, expected pollutants, sample temperature and the outputs required by your control system. The LAR NitriTox datasheet is available for download on this page. Our Muscat team will review the application, confirm availability and support installation and service across Oman and the GCC.