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1 ON-LINE ANALYSIS OF modeltekst te CHEMICAL OXYGEN DEMAND IN WWTPs A presentation by AppliTek NV Belgium

2 modeltekst te Founded in 1985 AppliTek stands for Applied Technology Member of the TETRAKTYS Group 2

3 Basic modeltekst processes in te a WWTP and COD analysis Standardized methods for measuring COD Continuous on-line COD measurement using wet-chemical oxidation AppliCOD Improvement of analysis response time AppliCOD Market approach TABLE OF CONTENT AppliCOD Operation and maintenance Environmental monitoring and turnkey solutions Conclusions 3

4 modeltekst te Basic processes in a WWTP and COD analysis 4

5 Nutrient parameters Nitrogen modeltekst te Phosphorus These are indispensable for growth of micro-organisms, but can be harmful for the quality of surface water. Biomass contains approximately 5-10% nitrogen and 2% phosphorus. influent BASIC WASTE WATER TREATMENT PLANT effluent Sludge waste 5

6 Organic sum parameters COD: Chemical Oxygen Demand modeltekst te BOD: Biological Oxygen Demand TOC: Total Organic Carbon Based on the molecular mass ratio between O 2 and C, the theoretical correlation factor between TOC and COD is In real life this depends on the type of waste water. COD could in some» Vijfde cases niveau be preferred to BOD 5 for daily analysis since it is more reproducible and results are available in a relatively short time. influent BASIC WASTE WATER TREATMENT PLANT effluent Sludge waste 6

7 Waste water and COD modeltekst te The pollution level is determined by measuring the equivalent amount of oxygen required to oxidize organic matter in the sample (expressed in mg/l). For example: glucose. C 6 H 12 O O 2 6CO 2 + 6H 2 O 1 mol glucose needs 6 mol O g glucose needs 192 g O 2 The COD for 1 g glucose is 1.07 g/g glucose. The efficiency of a treatment process is commonly expressed as COD Removal, expressed as a percentage of the organic load that has been purified. For example: Influent COD (mg/l) Effluent COD (mg/l) COD removal % 7

8 modeltekst Standardized te methods for measuring COD 8

9 Standard Method 5220 C modeltekst te Standard Method 5220 D Method 5220 C describes the titrimetric method; Method 5220 D describes the colorimetric method. These closed reflux methods are economical in the use of metallic salt reagents and generate small quantities of hazardous waste. Compared to open reflux, the volatile organic compounds in the sample are more completely oxidized because of longer contact with the oxidant. 9

10 International Standard Method ISO 6060 modeltekst te The International Organization for Standardization also describes a method for the determination of the COD of water. By means of titration. For many years, the strong oxidizing agent potassium permanganate has been used for measuring COD. The potassium permanaganate's effectiveness varied widely and in many cases BOD measurements were greater than results from COD measurements. Nowadays potassium dichromate (K 2 Cr 2 O 7 ) has been shown to be the most effective oxidizing agent: it is relatively cheap, easy to purify, and is able to oxidize almost all organic compounds. 10

11 modeltekst Continuous te on-line COD measurement using wet-chemical oxidation 11

12 AppliCOD analysis principle modeltekst te The analysis principle is similar to ISO 6060 Involves digesting the sample in a boiling mixture of strong sulfuric acid and dichromate Derde in the presence niveauof silver salts. The oxidizable matter ensures reduction of dichromate into Cr(III) The light absorbance» Vijfde of the niveau digested sample is directly related with the formed Cr (III) and indirectly with the concentration of organic compounds that are chemically oxidized. Digestion Solution Result Sample Stream Oxidation Vessel Analysis Vessel Silver sulfate/sulfuric acid Oxidation at 150 C 12

13 AppliCOD analysis scheme Ag2SO4 modeltekst +H2SO4 te K2Cr2O7 + HgSO4 MP2 vent MP3 MP1 Sample pump M Size14 / 24rpm M Overpressure Pump COOLER Water M RP1 Photometer 604nm DP1 M Sample Standard Water 13 Drain

14 AppliCOD absorbance measurement modeltekst te After digestion the sample is transferred to the analysis vessel where the light absorbance in the 600 nm region is measured ANALYSIS VESSEL COLORIMETER 14

15 AppliCOD absorbance measurement modeltekst te After digestion the sample is transferred to the analysis vessel where the light absorbance in the 600 nm region is measured No direct contact of sample with the optical components ANALYSIS VESSEL COLORIMETER DETECTOR LED 15

16 AppliCOD analysis results modeltekst te Certifiable results needed to comply with surface water and ground water legislation. High accuracy ( 5%) over an extended measuring range Repeatability of 5% at full scale Chloride interference is minimal thanks to the addition of mercuric sulfate (HgSO 4 ) Response time: 2 hours 16

17 modeltekst te AppliCOD Improvement of analysis response time 1. Accelerated Response Time Algorithm 2. Micro-wave digestion 17

18 modeltekst te METHOD 1 Accelerated Response Time 18

19 Advanced principle AppliCOD modeltekst te A cost-effective acceleration of the standard analysis method by means of a mathematical algorithm. This algorithm can be activated for incoming waste water, provided that it shows little matrix variations Analysis time is reduced from 2 hours to 30 minutes Response time: 30 minutes 19

20 modeltekst te METHOD 2 Micro-wave digestion 20

21 Advanced principle AppliCOD modeltekst Normally aromatic te hydrocarbons require 2 hours of oxidation Instead of conventional heating, micro-wave technology is applied. Using focused microwaves the response time is reduced to a mere 20 minutes through Vierde the niveau accelerated oxidation of organic substances. Independent from variations in the waste water s matrix Response time: 20 minutes 21

22 modeltekst te AppliCOD Market approach 22

23 Typical applications modeltekst Influent monitoring te Effluent monitoring influent Data Collection Data Collection effluent Sludge waste 23

24 Typical applications: influent monitoring modeltekst te The capacity of an activated sludge system shows well defined limits and the effect of overloading results in a wash out of solids. In case of calamity, the consequences on the effluent quality may continue for days. The influent matrix needs to be defined to give an idea of the variations in function of time (week, day, even hour) On-line, fast, continuous monitoring is the solution for collecting the appropriate data 24

25 Typical applications: effluent monitoring modeltekst te Stringent effluent quality standards can implicate the use of on-line analysis for monitoring the effluent and the process, in addition to on-line nutrient analyzers Water processes sensible to calamities can quickly be identified Again, on-line, fast, continuous monitoring is the solution for collecting the appropriate data 25

26 Potential customers modeltekst te Municipal waste water treatment plants And: Petrochemical industry Pharmaceutical industry Fertilizer industry Automobile industry AppliCOD 26

27 modeltekst te AppliCOD Operation and Maintenance 27

28 Operation requirements modeltekst te In compliance with the official requirements, the AppliCOD needs chemicals for proper operation: Digestion Solution = mol/l K 2 Cr 2 O g/l HgSO 4 Sulfuric acid + 10 g/l Ag 2 SO ml H 2 SO 4 (95-97%) Consumption of these chemicals depends on the analysis frequency and waste water matrix. AppliTek advises to purchase the chemicals locally for economy and safety. Other products: - Demineralized water for automatic zeroing - Standard solution for automatic validation 28

29 Maintenance requirements modeltekst te The AppliCOD uses the best of available materials including robust pumps, a userfriendly computer and a corrosion-resistant protective cabinet. Maintenance includes: Replacement of sample pump tubing every 4 months 29

30 modeltekst te Conclusions 30

31 What can you expect from modeltekst te implementing the AppliCOD? Continuous monitoring of the influent or effluent quality Advanced wet-chemical oxidation High accuracy & certifiable results User-friendly interface Limited downtime AND: A technology supported by a company whose know-how can assist you in optimizing and commissioning WWTP s. 31