Use of Spectral Induced Polarization in environmental applications Gerodimou Konstantina Τρίτη, 28 Μαρτίου 2017

Structure Purpose of the survey Monitoring methods applied – Geophysical, Geochemical Contaminant used – Textile waste waters Remediation agent – Biochar Experimental Study Results Interpretation Conclusions

Purpose of the Survey Physicochemical changes Contaminant + biochar SIP signal Contaminant + biochar Physicochemical changes Potential for geophysical monitoring tool of the process Δεν το καταλαβαίνω αυτό... to biogeophysics δεν έχει σχέση αν θέλεις να κάνεις ένα flowchart τότε κάνε κάτι σαν αυτό Contaminant - biochar (remediation agent) - physicochemical changes - SIP signals; potential for geophysical monitoring of the process Rapidly evolving earth science - Biogeophysics

Environmental & Νear Surface Geophysics Geophysics is the application of physics to investigate the Earth Solid earth geophysics studies the interior of the earth (up to the core) Near surface geophysics is concerned with the upper crust. Geophysics is not limited on Earth, can be applied in other planets / extraterrestrial objects (e.g. moon, which is not a planet) NSG - typically we say < 100 m; where we have practical applications and typically economic aims Reynolds defines environmental geophysics: The application of geophysical methods to the investigation of near surface bio-physico-chemical phenomena that are likely to have implications for the local environment

Types of problems addressed? Ground water exploration Contaminant mapping and monitoring Geohazards Geologic mapping Archaeology Advantages Non (or minimally) invasive Cost effective High spatial / temporal resolution Easier application Remote monitoring / operation Long term continuous, application Based on the problems addressed, change the previous title to Near Surface Geophysics (geologic mapping, hazards and archaeology are not 'Environmental') Highlight that they are indirect method, so direct method verification / correlation / support is always needed

Geophysical Methods Electromagnetics (MT, TDEM, FDEM, GPR) (active, passive) Gravity (passive) Magnetics (passive) Seismics (Refraction, Reflection, Surface waves, Earthquakes) (active, passive) Electrical (ERT, SP, IP, SIP) (active, passive)

SIP (Spectral Induced Polarization) IP (induced Polarization) SIP : The extension of IP Non invasive electrical method Applies DC current to the subsurface using 2 electrodes Soil media act as a capacitor Electrochemical reactions Voltage potential Polarization Chargeability Measurements represented by the complex conductivity Range of frequencies Electrochemical polarization MW polarization Electrical Double Layer (EDL) Diffuse Layer polarization Stern Layer polarization IP can be minimally invasive, in reality an AC (low frequency) current is applied we typically use 4 electrodes; 2 for injection and 2 for measurements what do you mean by electrochemical reactions? what is the voltage potential? SIP τι σημαίνει Meaurement represented by the complex conductivity? ποια η διαφορά IP - SIP?

Spectral Induced Polarization(SIP) IP (Induced Polarization) Electrode polarization

Electrical Double Layer (EDL) Electrical double layer, diffuse and Stern layer (Slater 2014) Tortuosity (Slater 2014) rock water

SIP (complex resistivity in frequency domain) (Slater 2014) Time Vp Ip Phase lag, ϕ Current Voltage C+ P- C- P+ a OK, γιατί όμως έχεις φωτό από field resistivity? ναι, έτσι εφαρμόζεται, αλλά το ίδιο και το IP & Resistivity magnitude Phase lag

Complex conductivity Is given by : ρ(ω) : complex resistivity ω:angular frequency αυτό να το συνδυάσεις με το προήγουμενο slide επίσης να πεις και κάτι γιατί κάνεις IP/SIP (να εξηγήσεις το real & imaginary component)

The wastewater Textile waste water (TWW) Reactive Red 120 (RR120) Chemical molecule (C44 H24 C12 N14 Na6 O20 S6)

Biochar (BC1) Solid heterogeneous substance produced by biomass pyrolysis Carbonization of biomass Organic carbon 81.9% Grain size : 2mm

Two types of adsorption Adsorption is the adhesion of atoms, ions or molecules from liquid to a surface Two types of adsorption

Experimental setup Portable Field/Lab Unit Acrylic tube columns

Experimental setup Liquid filling Non polarized (Ag/AgCl) electrodes παράξενη φαίνεται η στήλη αριστερά' σα να έχει biochar στα άκρα, και καθαρή άμμο στη μέση

Calibration Measurements Standard solutions Geometric factor for each column

Tests Reference column (sand) and RR120 aqueous solution Current 100% biochar and RR120 aqueous solution Reference column (sand) and RR120 aqueous solution Current electrodes Potential electrodes

Dynamic and semi-static measurement sets Semi-static mode we stopped the flow in every loop. Sample In situ conductivity measurement Continuation of the flow Dynamic mode Continuous slow flow. Samples every 10 min. In situ conductivity measurement. Samples in both cases end up in chemistry lab for adsorption measurements.

Channel 1 – Column 7 (20% biochar)

Channel 1 As time passes, peak frequency shifts towards higher frequencies. Average peak frequency (PF) 0.7Hz SINGAL OR NOT ??? Accuracy of the instrument :0.5mrad. The phase changes from 4-12 mrad for all frequencies which is greater than the accuracy of the instrument.

RR120 VS Water the second statement is not clear with the data presented here Results The phase at RR is frequency dependent (clearly shifted at higher frequencies)

10% Biochar, Phase, Imaginary & Real conductivity, Resistivity change at PF:63Hz

BIOGEOPHYSICS : Integration of geophysical measurements with geochemical analysis 10% Biochar-RR Dynamic χμμμ, εξαρτάται τι θα πεις....

20% Biochar-RR PF: 10 Hz Semistatic 20% Biochar-RR PF: 1 Hz Dynamic Οκ, καλύτερο correlation 20% Biochar-RR PF: 1 Hz Dynamic

100% Biochar (RR & Water) - Imaginary & Real conductivity, Phase and Resistivity change at 1 Hz distinctively different trends different phase magnitude Water

100% Biochar  Frequency dependence 0.1 Hz RR Water 1000 Hz Water RR 10 Hz RR Water RR Water 1 Hz 100 Hz RR Water

? 100% Biochar-RR VS 100% Biochar-Water, PF: 1 Hz - Dynamic FTIR (biochar before and after treatment) + DEBYE decomp. DECOLORATION Visually evident Decoloration after 20 min

Conclusions (1) From the diagrams its clear that there is consistency between the measurements, therefore we present reliable results. Waters and wastes trend is parallel and same, but wastes amplitude is greater. This means that the TWW it is been detected. It has strong spectral signature. Very significant for the water/TTW comparison is that waters resistivity increases with time in contrast with TWW which decreases with time. The presented results might suggest a correlation between the geophysical data trend, and the geochemical data trend RR related processes have distinctively different geophysical signal than water only The geophysical behaviour appears to be different between water and RR; water saturated columns show increase over time, whereas RR contamination shows decreas - the links with adsorption processes should be further examined

Biochar concentration Conclusions (2) The presented results might suggest a correlation between the geophysical data trend and the geochemical data trend. The geophysical behavior appears to be different between water and RR. Increasing the BIOCHAR concentration, the adsorption increases. Biochar concentration Adsorption 10 % 16 % 20 % - semi static 37 % 20 % - dynamic 38 % 100 % 84 %

Conclusions (3) Dynamic and semi-static experimental conditions have the same adsorption. It is still unknown, which chemical mechanisms and type of adsorption took place into the chamber BUT this work is still in progress (FTIR from Aksaray University-Turkey and DEBYE decomp. Rutgers University, US)

Acknowledgements I would like to thank, Assistant Prof. Dimitrios Kalderis (TEI Crete) for his useful advices and continuous support on geochemical analysis and interpretation of the final results Panagiotis Kirmizakis (Queens Belfast Univ., UK) for introducing experimental setup of SIP measurements Associate Research Prof. Dimitrios Ntarlagiannis (Rutgers Univ., US) for supporting my research and teach me the SIP method Prof. Berkant Kayan (Aksaray Univ., Turkey) for applying the FTIR method to our biochar samples Ass. Prof. Andrea Ustra (Univ. Sao Paolo, Brazil) and Sina Saneiyan (Rutgers Univ., US) for applying the Debye decomposition to our datasets