Contributions to online measurement systems for the investigation of wastewater toxicity on activated sludge

VIETNAM NATIONAL UNIVERSITY, HANOI VNU UNIVERSITY OF SCIENCE Ferdinand Friedrichs CONTRIBUTIONS TO ONLINE MEASUREMENT SYSTEMS FOR THE INVESTIGATION OF WASTEWATER TOXICITY ON ACTIVATED SLUDGE PH.D THESIS IN CHEMISTRY Ha Noi – 2018 VIETNAM NATIONAL UNIVERSITY, HANOI VNU UNIVERSITY OF SCIENCE Ferdinand Friedrichs CONTRIBUTIONS TO ONLINE MEASUREMENT SYSTEMS FOR THE INVESTIGATION OF WASTEWATER TOXICITY ON ACTIVATED SLUDGE Branch: Environmental Chemistry Code: 62440120 PH.D THESIS IN CHEMISTRY Supervisors: Assoc Prof Dr Do Quang Trung Prof Dr Dr Wolfgang Genthe Ha Noi – 2018 Acknowledgement First of all, I would like to thank both of my supervisors, Prof Dr Dr Genthe who gave me the chance to work for the AKIZ project in Vietnam as an employee of LAR Process Analysers AG, for giving me the chance to work on such an exciting project, any kind of support, inspiring discussions and arranging enough time to finalize the Ph.D thesis Many thanks to Prof Dr Do Quang Trung as my supervisor from the Vietnamese site from Vietnam National University I highly appreciate for giving me the opportunity to my Ph.D at the Vietnam National University VNU Many thanks for the support to finalizing my Ph.D subjects, to give me the chance to work on research projects with students from VNU and the interesting discussion related to my Ph.D thesis Secondly, many thanks to all my colleagues at LAR Process Analysers, the AKIZ team, and the members and students from VNU who supported during my time in Vietnam doing my Ph.D thesis Special thanks to my lab members Ms Huyen, Mr Nhan and Mrs Lanh for the support in the laboratory and the beautiful time spent together in Can Tho Also many thanks to the students from VNU Mr Bac, Ms Dung and Ms Lanh for coming to Can Tho to research at the AKIZ laboratory Many thanks to my colleagues from LAR Process Analysers AG for the support regarding technical issues related to the analysers and the interesting discussion related to the research topic Therefore I want to acknowledge Thomas, Rafael, Olga, Olaf, Winfried, Gerhard, and Agnes Many thanks to the project leader Prof Dr Rudolph as project leader and Dominic, Rene, Sandra and Mr Long for coordinating the AKIZ Project Last but not least, I would like to thank family and friends for their patience and care, especially to my wife Huyen, my son Nico Tri, and my daughter Lina Kim for keeping me in a good mood II I Declaration I hereby declare that I have written the present thesis independently and without the use of others than the indicated sources Berlin, 20th June 2017 Signature: Acknowledgement First of all, I would like to thank both of my supervisors, Prof Dr Dr Genthe who gave me the chance to work for the AKIZ project in Vietnam as an employee of LAR Process Analysers AG, for giving me the chance to work on such an exciting project, any kind of support, inspiring discussions and arranging enough time to finalize the Ph.D thesis Many thanks to Prof Dr Do Quang Trung as my supervisor from the Vietnamese site from Vietnam National University I highly appreciate for giving me the opportunity to my Ph.D at the Vietnam National University VNU Many thanks for the support to finalizing my Ph.D subjects, to give me the chance to work on research projects with students from VNU and the interesting discussion related to my Ph.D thesis At this point I would like to acknowledge Prof Dr mult, Rudolph as the leader of the AKIZ project, who always supported me, especially with the publication of scientific articles Secondly, many thanks to all my colleagues at LAR Process Analysers, the AKIZ team, and the members and students from VNU who supported during my time in Vietnam doing my Ph.D thesis Special thanks to my lab members Ms Huyen, Mr Nhan, Mr Huy and Mrs Lanh for the support in the laboratory and the beautiful time spent together in Can Tho Also many thanks to the students from VNU Mr Bac, Ms Dung and Ms Hanh for coming to Can Tho to research at the AKIZ laboratory Many thanks to my colleagues from LAR Process Analysers AG for the support regarding technical issues related to the analysers and the interesting discussion related to the research topic Therefore, I want to acknowledge Thomas, Rafael, Olga, Olaf, Winfried, Gerhard, and Agnes Many thanks to Dominic, Rene, Sandra and Mr Long for coordinating the AKIZ Project and their support Last but not least, I would like to thank family and friends for their patience and care, especially to my wife Huyen, my son Nico Tri, and my daughter Lina Kim for keeping me in a good mood Many thanks to my parents who always supported me during my studies and the entire life VI Declaration I hereby declare that I have written the present thesis independently and without the use of others than the indicated sources Berlin, 16th April 2018 Signature: Abstract Removal of nitrogen compounds and organic pollutants from wastewater is one of the essential issues in wastewater treatment Commonly applied for this treatment step is the activated-sludge process To guarantee a proper operation of this process, it is necessary to monitor the inhibitory effect of toxic substances on activated-sludge bacteria This is commonly done by the activated-sludge respiration-inhibition test But there is still a lack of knowledge, which parameters have an influence on the stability and sensitivity of the biological test In the literature, the inhibitory effects of single toxicants on activated sludge may vary up to three orders of magnitudes The aim of the study is to increase the sensitivity of toxicants on the activated-sludge respiration test to create an adjustable biosensor To this end, the research question is as follows: Which parameters have an influence on the sensitivity of the activated-sludge respiration-inhibitions test? The research question is answered through experiments using the international standardized activated-sludge respiration-inhibition test and the two online-respirometers NitriTox and Biomonitor of LAR Process Analysers AG To influence the sensitivity of these bio assays following parameters were investigated pH, temperature, oxygen concentration in the fermenter, incubation time, nutrient limitation and biomass concentration These experiments were realized with using Zn(II), Cu(II), Cr(VI) and 3,5 DCP as toxicants A series of experiments are described with this objective, and showed in each case, that the sensitivity of the bioassay could be varied by the investigated parameters The sensitization of the test organisms can be explained by altering the activity of the bacteria and also the speciation of the toxicants in the presence of the nutrient solution and its biological degradation products It is, therefore, possible to detect toxic pollutants in lower concentrations, which have an inhibiting effect on activated-sludge bacteria I expect that this new approach is applied to detect inhibiting substances in wastewater in lower concentrations to protect activated-sludge bacteria in a wastewater treatment plant more efficiently Additionally, a mobile laboratory was developed and assembled to conduct wastewater monitoring in seven industrial zones across the country Vietnam with toxicity as a critical parameter The aim of the monitoring campaigns was to apply the online respiration inhibition respirometer NitriTox to a case study in which extend the activated-sludge process of industrial wastewater treatment plant are inhibited by toxic wastewaters in Vietnam The high necessity of monitoring the toxicity of industrial wastewater can be proved that toxic wastewater occurred in five of the seven tested industrial zones In conclusion, the NitriTox was applied successfully in the frame of the measurement campaigns in seven industrial zones in Vietnam LIST OF CONTENTS Acknowledgement I Declaration II Abstract III List of Abbrevations .X List of Figures XI List of Tables XV Introduction 1 The Importance of the Topic Objectives The new Points of this Dissertation Chapter 1: Literature Review 1.1 Wastewater Treatment Plant Overview 1.1.1 Activated-Sludge Process 1.1.2 Nitrification 1.2 Toxicity Monitoring 1.2.1 Inhibition and Toxicity 1.2.2 Necessity of Toxicity Monitoring 1.2.3 Sum-Parameters in Water Monitoring 10 1.2.4 Sources of Heavy Metal Pollution 11 1.2.5 Toxicity Assessment Methods to Determine the Inhibition of Pollutants on ActivatedSludge Bacteria 12 1.2.6 Activated-Sludge Respiration-Inhibition Test 14 1.2.6.1 Offline Respiration-Inhibition Measurements 14 1.2.6.2 Online Respiration-inhibition Measurements .14 1.2.7 Comparison of the Toxicity-Assessment Methods used to determine the Inhibition of Pollutants on Activated-sludge Bacteria 17 1.2.8 Comparison of EC 50 Values of Activated-Sludge Inhibition-Test .19 1.2.8.1 Copper 19 Footages of the Mobile Laboratory Figure Annex 8: Interior view of the mobile laboratory; 1) Ammonitor: ammonium measurement, 2) WaterSam: automatic sample taker 3) ELOX: E-COD measurement, 4) Quick TOC Ultra: TOC and TNb measurement, 5) NitriTox: toxicity measurement, 6) refrigerator Figure Annex 9: Interior view of the mobile laboratory; 1) pure water supply system, 2) uninterruptable power supply, 3) laboratory bench with a balance, high pressure filtration, photometer and cuvette tests, 4) metrological weather station Tables Table Annex 2: Comparison results DIN ISO 8182 using synthetic wastewater and Sodium acetate as nutrient solution Nutrient Compound Solution Synthetic Cr wastewater Cr Sodium acetate Synthetic wastewater Cu Cu Sodium acetate Synthetic Zn wastewater Zn Sodium acetate Synthetic wastewater 3,5 DCP 3,5 DCP Sodium acetate EC 50 mg L-1 N Stdev mg L-1 CV % Factor of Sensitization 37.1 20.2 4 1.1 0.7 3.0 3.6 1.8 25.5 3.3 4 1.5 0.6 5.9 18.8 7.7 39.2 6.5 4 0.9 1.1 2.4 16.4 6.0 20.8 6.2 4 0.5 0.7 2.2 11.8 3.4 Table Annex 3: Comparison Biomonitor and DIN method Standard Nutrient Solution Zn Zn Cu Cu( Cr Cr 3,5 DCP 3,5 DCP Biomonitor DIN ISO 81 92 Biomonitor DIN ISO 81 92 Biomonitor DIN ISO 81 92 Biomonitor DIN ISO 81 92 SdtDev EC 50 mg L-1 120.4 39.2 65.4 25.5 40.15 37.1 112 20.8 14.81 0.9 7.59 1.5 3.57 1.1 11.65 0.5 CV Factor of (%) Sensitization 12.30 2.4 11.60 5.9 8.9 10.4 2.2 3.07 2.56 1.08 5.38 Table Annex 4: Influence Nutrients to Biomonitor measurements Standard Nutrient Solution Zn Synthetic Wastewater Zn Zn Synthetic Wastewater Sodium acetate Sodium acetate Zn Synthetic Wastewater Cu Cu Cu Cu Cr Cr Cr Cr Synthetic Wastewater Sodium acetate Sodium acetate Synthetic Wastewater Synthetic Wastewater Sodium acetate Sodium acetate Synthetic 3,5 DCP Wastewater Synthetic 3,5 DCP Wastewater 3,5 DCP Sodium acetate 3,5 DCP Sodium acetate Incubation EC 50 mg L-1 Time SdtDev CV (%) Factor of Sensitization 30 120.4 45 30 45 14.8 12.3 102.3 73.3 45.3 13.8 5.6 4.5 13.5 7.7 10.1 65.4 62.4 24.22 15.3 7.5 8.5 2.5 0.9 11.6 13.7 10.5 6.3 3.5 8.9 38.5 17.39 12.45 4.6 1.4 0.9 12.1 8.4 7.6 109.7 74 34.5 11.6 8.9 8.2 3.2 10.4 8.2 11.2 9.4 1.18 1.64 2.66 30 45 30 45 30 40.15 45 30 45 30 45 30 45 112 2.70 1.05 4.27 1.04 2.31 3.22 1.02 1.51 3.25 Table Annex 5: Toxicity measurements to activated sludge: according to DIN ISO 8192 and NitriTox measurement according to DIN ISO 8192 Standard Method SdtDev CV EC 50-1 % mg L-1 mg L 27 1.1 4.2 Factor of Sensitization 1.08 25 53 1.3 1.6 5.2 3.2 1.08 NitriTox according DI N ISO 8192 49 DIN ISO 8192 57 3.5 2.6 7.2 3.5 1.03 3,5 DCP NitriTox according DI N ISO 8192 55 DIN ISO 8192 36 5.5 1.2 7.4 3.6 1.06 3,5 DCP NitriTox according DIN ISO 8192 34 1.8 5.4 Cu Cu Cr Cr Zn Zn DIN ISO 8192 NitriTox according DIN ISO 8192 DIN ISO 8192 Table Annex 6: NitriTox Measurement according to DIN ISO 8192; Chapter 3.1 and Chapter 3.3.1.3 Standard Method Cu Cu Cr Cr Zn Zn 3,5 DCP 3,5 DCP DIN ISO 8192 - chapter 3.3.1.3 DIN ISO 8192 - chapter 3.1 DIN ISO 8192 - chapter 3.3.1.3 DIN ISO 8192 - chapter 3.1 DIN ISO 8192 – chapter 3.3.1.3 DIN ISO 8192 - chapter 3.1 DIN ISO 8192 - chapter 3.3.1.3 DIN ISO 8192 - chapter 3.1 EC 50 mg L-1 27 26 53 37 57 39.2 36 20.8 Factor of Sensitization 1.04 1.43 1.45 1.73 Table Annex 7: Influence of Nutrients to NitriTox measurement using activated sludge as nutrient solution: Nutrient Solution EC 50 Sodium acetate mg L-1 51.0 StdDev mg L-1 6.4 Factor of CV Sensitization 3.3 2.2 Synthetic Wastewater Sodium acetate 110.8 121.0 4.9 4.7 5.4 5.7 1.2 Synthetic Wastewater Sodium acetate 142.9 2.3 6.3 6.2 9.0 0.1 5.4 3,5 DCP Synthetic Wastewater Sodium acetate 12.2 29.8 3.4 5.7 0.4 1.7 1.5 3,5 DCP Synthetic Wastewater 43.2 4.7 2.0 Standard Zn Zn Cr Cr Cu Cu Table Annex 8: Influence of Nutrients to NitriTox measurement using LAR nitrifiers as nutrient solution: Standard Nutrient Solution EC 50 mg L-1 StdDev mg L-1 Factor of CV Sensitization Zn Ammonia Bicarbonate 6.4 8.1 0.5 7.2 Zn Synthetic Wastewater 46 4.9 2.2 Cr Ammonia Bicarbonate 34 7.5 2.6 1.7 Cr Synthetic Wastewater 59 4.6 2.7 Cu Ammonia Bicarbonate 13 7.3 0.9 5.0 Cu Synthetic Wastewater 65 6.7 4.3 3,5 DCP Ammonia Bicarbonate 12.4 6.9 0.8 1.9 3,5 DCP Synthetic Wastewater 24 4.2 1.0 Table Annex 9: Influence of the pH value to the EC 50 values of Zn(II), Cu(II) and Cr(VI) Standard pH Zn Zn Zn Zn Cr Cr Cr Cr Cu Cu Cu Cu 3,5 DCP 3,5 DCP 3,5 DCP 3,5 DCP 11 11 11 11 EC 50 SdtDev mg L-1 mg L-1 CV % Factor of Sensitization 37.5 40.4 60.7 61.7 12.3 17.8 500 500 35.4 37.5 39.3 42.5 62.5 65.5 61.5 41 3.6 5.2 5.3 3.6 3.2 4.1 4.2 6.7 6.3 4.2 5.3 4.8 5.8 6.2 1.65 1.4 2.1 3.2 2.2 0.4 0.7 1.5 2.5 2.5 1.8 3.3 3.1 3.6 2.5 40.65 1.20 0.66 Table Annex 10: Influence of the Temperature to the EC 50 values of Zn(II), Cu(II) and Cr(VI) Standard T °C Zn Zn Zn Cu Cu Cu Cr Cr Cr 3,5 DCP 3,5 DCP 3,5 DCP 10 25 40 10 25 40 10 25 40 10 25 40 EC 50 SdtDev mg L-1 mg L-1 CV Factor of % Sensitization 25.1 15.3 9.6 40.4 31.7 12.5 70.3 56.3 47.9 17.9 22.1 25.5 4.2 7.5 7.3 8.5 6.9 8.4 7.5 8.6 5.3 8.5 11.6 7.8 1.33 1.15 0.70 3.43 2.18 1.05 5.27 4.84 2.54 1.52 2.56 1.99 1.64 2.63 1.28 3.23 1.25 1.47 0.81 0.70 Table Annex 11: Influence of the biomass concentration on the EC 50 values of Zn(II), Cu(II) and Cr(VI) Standard Zn Zn Zn Zn Zn Zn Cu Cu Cu Cu Cu Cu Cr Cr Cr Cr Cr Cr 3.5 DCP 3.5 DCP 3.5 DCP 3.5 DCP 3.5 DCP 3.5 DCP c TSS - Fermenter g L-1 1.5 1.5 1.5 0.8 0.8 0.8 1.5 1.5 1.5 0.8 0.8 0.8 1.5 1.5 1.5 0.8 0.8 0.8 1.5 1.5 1.5 0.8 0.8 0.8 Ration Biomass % EC 50-1 mg L SdtDev CV % Factor of Sensitization 10 15 10 15 10 15 10 15 10 15 10 15 10 15 10 15 12.2 7013.8 15.2 13.9 14.2 15 15.3 17.3 20.76 13.75 15.5 25 52.6 79.7 106.6 39.4 68.2 95.8 19.61 21.875 23.9 20 22 25 8.3 9.2 5.3 6.9 6.3 4.6 7.3 6.3 6.3 7.3 5.3 8.4 5.8 7.4 8.2 8.3 7.8 7.8 8.2 6.9 7.4 6.1 8.7 1.25 1.10 1.0 1.2 0.8 1.0 0.8 0.6 1.1 1.0 1.3 1.0 0.8 2.1 3.0 5.8 8.7 3.2 5.3 5.7 1.5 1.7 1.6 1.4 1.3 2.1 1.08 1.06 1.36 1.20 1.82 1.61 2.03 1.34 2.43 1.40 1.22 1.09 1.25 1.14 Table Annex 12: Influence of the incubation time on the EC 50 values of Zn(II), Cu(II) and Cr(VI) for activated sludge Standard Incubation Time Zn Zn Cu Cu Cr Cr 3,5 DCP 3,5 DCP 30 min 30 min 30 min 30 EC 50 CV -1 SdtDev mg L % Factor of Sensitization 131 72 42 23 90 49 90 33 1.8 11.0 3.4 3.9 1.9 5.1 4.3 5.6 1.7 8.4 4.7 9.2 8.2 5.7 8.8 6.2 5.3 1.8 1.8 2.7 Table Annex 13: Influence of the incubation time on the EC 50 values of Zn(II), Cu(II) and Cr(VI) for nitrifiers Standard Incubation Time Zn Zn Cu Cu Cr Cr 3,5 DCP 3,5 DCP 30 min 30 min 30 min 30 EC 50 mg L-1 44.4 20.3 70.3 45.2 70.2 53.2 56.4 30.6 SdtDev Factor of CV % Sensitization 3.7 1.8 4.9 4.2 5.5 5.6 4.1 2.2 8.4 8.7 6.9 9.3 7.8 10.5 7.3 7.2 2.2 1.6 1.3 1.8 Table Annex 14: Influence of exposure time in the measurement Phase II Standard Time - Measurement Phase II s Zn Zn Zn Cr Cr Cr Cu Cu Cu 3,5 DCP 3,5 DCP 3,5 DCP 180 300 420 180 300 420 180 300 420 180 300 420 EC 50 mg L-1 30.4 26.7 26.5 32.7 31.2 31.4 37.2 29.7 8.8 17.9 17.8 17.4 SdtDev 1.8 2.0 1.5 1.86 1.84 2.13 2.71 2.49 0.62 1.36 1.40 1.46 CV % 6.2 7.5 5.8 5.7 5.9 6.8 7.3 8.4 7.1 7.6 7.9 8.4 Factor of Sensitization 1.14 1.15 1.05 1.04 1.25 4.23 1.01 1.03 Table Annex 15: Influence of the aeration rate for the fermenter to the toxicities for 3,5 DCP, Zn, Cu and Cr Standard Aeration Rate EC 50 mg L-1 L h-1 SdtDev mg L-1 CV % Factor of Sensitization Cu Cu Cr Cr Zn Zn 3,5 DCP 3,5 DCP 50 50 50 50 50 36 33 26 41 23 53 34 3.2 2 1.5 3.7 2.6 6.4 5.6 6.1 5.8 9.0 9.3 1.4 1.3 1.8 Table Annex 16: Influence of SO4 to NitriTox measurements c(SO4) EC 50 SdtDev Factor of Standard 3,5 DCP 3,5 DCP Zn Zn Cr Cr Cu Cu mg L-1 1000 1000 1000 1000 mg L-1 24 26 37 36 29 31 43 43 mg L-1 2.7 2.1 2.4 2.9 2.7 2.2 3.5 3.9 CV % Sensitization 0.92 11.8 8.4 6.7 8.3 9.6 7.2 8.3 9.3 1.03 0.94 1.00 Table Annex 17: Influence of Koalin and filtration: Chapter 3.3.3.2 Standard Sample EC 50 mg L-1 SdtDev CV % g L-1 Kaolin 0.5 g L-1 Kaolin before filtration Zn 0.5 g L-1 Kaolin after filtration Cu g L-1 Kaolin Cu 0.5 g L-1 Kaolin before filtration Cu 0.5 g L-1 Kaolin after filtration Cr g L-1 Kaolin Cr 0.5 g L-1 Kaolin before filtration Cr 0.5 g L-1 Kaolin after filtration 3,5 DCP g L-1 Kaolin 3,5 DCP 0.5 g L-1 Kaolin before filtration 3,5 DCP 0.5 g L-1 Kaolin after filtration 3.8 4.1 0.3 0.1 8.3 4.7 1.08 4.9 0.2 4.8 1.29 2.5 2.3 0.1 0.1 5.2 6.4 0.92 3.7 0.2 6.4 1.48 18.3 17.9 1.2 1.3 6.6 7.3 0.98 20.1 1.6 8.3 1.10 5.3 5.5 0.4 0.3 9.4 5.8 1.04 6.8 0.5 7.9 1.28 Zn Zn Factor of Sensitization Table Annex 18: Monitoring results; Biomonitor, NitriTox, Heavy metals Toxicity Sampling NitriTox Biomonitor Cr Date/Time % % mg L-1 23.01.14 10 am 23.01.14 pm 27.02.14 11 am 27.02.14 pm 27.02.14 pm 28.02.14 3:15 pm Cr(VI) mg L-1 Cu mg L-1 Ni mg L-1 Pb mg L-1 Zn mg L-1 79 51 12.98 9.84 0.009 107 81 53 7.73 2.28 0.053 0.021 120.1 58 24 8.3 0.013 0.031 0.328 90.63 48 23 17.65 0.047 0.079 0.675 135.5 60 48 33.14 0.099 0.053 0.470 85.85 56 18 81.61 0.848 0.094 1.523 186.73 Table Annex 19: Summary of acquired data with NitriTox during monitoring campaigns of industrial wastewater in Vietnam Date Time Measurement Point (MP) Toxicity % January 2015 January 2015 January 2015 January 2015 January 2014 January 2014 January 2014 January 2014 January 2014 January 2014 January 2014 January 2014 January 2014 March 2015 March 2015 March 2015 March 2015 March 2015 March 2015 March 2015 March 2015 March 2015 March 2015 08:00 12:00 16:00 20:00 00:00 04:00 05:00 09:00 10:00 11:00 12:00 17:00 19:00 19:00 19:00 19:00 07:00 12:00 15:00 19:00 07:00 19:00 07:00 Tra Noc – open storm-water canal - MP Tra Noc – open storm-water canal - MP Tra Noc – open storm-water canal - MP Tra Noc – open storm-water canal - MP Tra Noc – open storm-water canal - MP Tra Noc – open storm-water canal - MP Tra Noc – open storm-water canal - MP Tra Noc – open storm-water canal - MP Tra Noc – open storm-water canal - MP Tra Noc – open storm-water canal - MP Tra Noc – open storm-water canal - MP Tra Noc – open storm-water canal - MP Tra Noc – open storm-water canal - MP Tra Noc - outlet Tra Noc - outlet Tra Noc - outlet Tra Noc - outlet Tra Noc - outlet Tra Noc - outlet Tra Noc - outlet Tra Noc - outlet Tra Noc - outlet Tra Noc - outlet 79 81 58 48 60 56 24 67 92 68 52 54 20 23 31 43 19 20 22 25 39 24 Table Annex 20: Summary of gained data during monitoring campaigns of industrial wastewater in Vietnam Date Time Measurement Point (MP) January 2015 January 2015 January 2015 January 2015 January 2015 January 2015 January 2015 January 2015 January 2015 January 2015 January 2015 April 2015 April 2015 April 2015 April 2015 April2015 April 2015 April 2015 April 2015 April 2015 April 2015 April 2015 Sept 2015 Nov 2015 Nov 2015 Nov 2015 Nov 2015 Nov 2015 Nov 2015 Nov 2015 Nov 2015 Nov 2015 08:00 10:00 12:00 14:00 12:00 14:00 10:00 12:00 14:00 08:00 12:00 14:00 14:00 14:00 14:00 14:00 14:00 14:00 14:00 14:00 14:00 14:00 10:00 09:00 21:50 05:50 09:50 13:50 17:50 14:00 14:20 14:40 Nam Sac - WWTP inlet Nam Sac - WWTP inlet Nam Sac - WWTP inlet Nam Sac - WWTP inlet Nam Sac - WWTP outlet Nam Sac - WWTP outlet Nam Sac - WWTP inlet Nam Sac - WWTP inlet Nam Sac - WWTP inlet Nam Sac - WWTP outlet Nam Sac - WWTP outlet Nam Sac - wastewater canal - MP Nam Sac - wastewater canal - MP Nam Sac - wastewater canal - MP Nam Sac - wastewater canal - MP Nam Sac - wastewater canal - MP Nam Sac - wastewater canal - MP Nam Sac - wastewater canal - MP Nam Sac - wastewater canal - MP Nam Sac - wastewater canal - MP Nam Sac - wastewater canal - MP Nam Sac - wastewater canal - MP Groz Beckert -chemical WWTP inlet Hoa Cam - wastewater canal - MP 1.2 Hoa Khanh - WWTP - inlet Hoa Khanh - WWTP - inlet Hoa Khanh - WWTP - inlet Hoa Khanh - WWTP - inlet Hoa Khanh - WWTP - inlet Hoa Khanh - wastewater canal - MP Hoa Khanh - wastewater canal - MP Hoa Khanh - wastewater canal - MP Toxicity % 12 30 32 31 19 10 65 71 31 10 13 12 12 5 15 47 86 94 12 33 76 85 10 24 14 15 15 25 29 34 ...VIETNAM NATIONAL UNIVERSITY, HANOI VNU UNIVERSITY OF SCIENCE Ferdinand Friedrichs CONTRIBUTIONS TO ONLINE MEASUREMENT SYSTEMS FOR THE INVESTIGATION OF WASTEWATER TOXICITY ON ACTIVATED SLUDGE Branch:... Influence of Nutrient Solution on Biomonitor Measurements .50 2.4.4.2 Influence of the sludge concentration on Biomonitor Measurements 51 2.4.4.3 Influence of the ASR value on Biomonitor Measurements... over the respiration rate of the activated- sludge microorganisms The respiration rate of reference water is set to a toxicity of 0%, and the total inhibition of the respiration rate to 100% The