WHEN IT COMES TO CONTINUOUS WATER ANALYSIS, ONE SIZE DOES NOT FIT ALL


Breaches of effl uent discharge regulations have hit the news headlines many times over the last year. Julian Edwards of ABB Measurement & Analytics in the UK explains why when it comes to ensuring strict legislation is met, there is no “one size fi ts all” solution for managing wastewater quality.


which are a major plant nutrient that can cause excessive plant growth, producing oxygen starvation that can kill fi sh and other aquatic life. Ensuring that the ammonia and hence the nitrate level is kept to a minimum is an essential before discharging to the environment.


Ammonia can be removed from water using one of four main methods – aeration, ion-exchange, breakpoint chlorination and biological denitrifi cation.


However, before treatment, levels of ammonia must be carefully monitored and measured. As it is colourless and odourless even in small amounts, the only way to detect it is through testing.


pH and ORP sensors group


Growing urban populations, the effect of climate change on rivers and water courses and increased demand are infl uencing the way water is managed, treated and discharged to the environment.


Increasingly strict legislation is focusing attention on the quality of discharged effl uent, placing added emphasis on the effective management and control of wastewater.


Continuous Water Analysis (CWA) systems are the best way to meet these demands as they give highly accurate, up to the minute information on process conditions. However, there is no ‘one size fi ts all’ approach as various conditions and legislative demands will determine what exact equipment and analysers are required.


The system and its components depend largely on the sources and makeup of the water entering the waste-water treatment works. Under the UK’s Environmental Permitting Regulations or EPR, all industrial companies discharging 50m3


When controlling ammonia levels, access to real-time information through CWA allows immediate action to be taken if any issues occur.


A suitable instrument for this application is the ABB Aztec 600 ISE ammonia analyzer. This analyser offers reliable and accurate measurement of ammonia concentrations which can include monitoring of source water and the removal of nutrients from wastewater.


The Aztec 600 uses a robust gas sensing ammonia electrode to ensure continuous measurement of the total ammonia nitrogen (TAN) concentration, which is the sum of the ammonia gas (NH3 and the ammonium cation (NH4+


). Controlling phosphates or more effl uent


per day to a watercourse or the sea must self-monitor their effl uent fl ows. Some companies that discharge to a particularly sensitive aquatic life area may have to self-monitor their effl uent fl ows even if they are discharging below 50m3 cases, this would be specifi ed in their PPC permit.


per day. In these


In some cases, factories will treat the water on site, particularly in the case of waste products that require specialist processes to render them suitable for discharge to a public water course or where the treatment would be prohibitively expensive for the water utility to treat.


In the fi nal discharge from a water utility’s treatment plant, some of the main parameters to monitor or control are ammonia, temperature, phosphate, pH, fl ow and turbidity/suspended solids.


Ammonia, a colourless, gaseous compound of hydrogen and nitrogen, is one of the major areas of concern. It is most often produced by industries and facilities such as power plants, commercial laundries, food and beverage factories and chemical production plants. In addition to ammonia being toxic, some of the by-products in nitrifi cation process can produce nitrates


IET ANNUAL BUYERS’ GUIDE 2022/23


Another major measurement priority for wastewater treatment is phosphates which are commonly used in water treatment to correct problems resulting from inorganic contaminants, including iron, manganese and calcium. Phosphates can also be found in fertilizer run-off, sewage, industrial manufacturing waste and common household items like detergents


)


However, excessive levels of phosphates released to the environment can have damaging effects, producing extra biomass that can lead to low oxygen levels in water courses.


Common methods of controlling phosphorous (P) rely on feedback control where phosphate (PO4


-3 ) is measured


at the outlet and fed back to the dosing system which adjusts the chemical dosing to maintain a consistent level.


Aztec 600


Although the feedback method has served well, AMP 7 now specifi es very low levels of P in discharged water down to 0.25mg/l, typically from 1.0mg/l previously. Depending on the works design this can require adding a tertiary solids removal (TSR) stage coupled with a more precise control method that can prevent any excess P reaching the environment. To achieve this, water utilities are looking at closed loop control (feed forward / feedback), where P is tested before the TSR stage to help determine the level of chemical dosing needed and then the P level is tested again at discharge and used as part of the feedback control calculation.


Another challenge faced by facilities is the varying ability of the water course ways to absorb the amount of phosphorous being discharged. They often show a high P concentration during summer low fl ows and more diluted concentrations during winter storm events. Also, discharging phosphorus into large, fast fl owing rivers such as the Thames will have a proportionately lower effect than discharging into a small, slow running stream.


The Aztec 600 phosphate analyzer from ABB meets all new consent levels and measures to the accuracy needed to meet AMP7 requirements. This instrument offers an accuracy down to 0.0016mg/l, helping utilities meet the prescribed level of 0.25mg/l


Cutting the cost of oxygen RVG200


Oxygen is one of the most important parameters in water quality management, from the treatment of waste at the aeration stage through to the point of fi nal discharge. Dissolved oxygen levels


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96