Application of MBR for the treatment of textile wastewater

Transcription

1 Application of MBR for the treatment of textile wastewater P. Damala, E. Katsou, J. Novakovic, K. Chatzikonstantinou, G. Karathanasi, A. Patsia, S. Malamis International Conference on Industrial Waste & Wastewater Treatment & Valorisation, May 2015, Athens National Technical University of Athens

2 Aim of the study The advanced treatment of textile wastewater using Membrane Bioreactor (MBR) Examine of COD and nitrogen removal, biomass activity and membrane fouling

3 Textile industry The textile finishing industry is the 2 nd biggest water consuming sector in Europe Large volumes of wastewater Substantial quantities of complex chemicals 6 millions tons of textile materials processed each year with a consumption of 600 million m³ of water Strict legislation governing the quality of treated effluent that is discharged to Asopos river MBR technology can help produce high treated effluent quality

4 Industry under examination (1/3) What kind of textile industry? Specializing in dyeing and finishing textile products Where is the industry situated? Inofita Schimatari (Prefecture of Viotia, Greece) Which problems has the area? Increased industrial development over the years Serious environmental problems due to the contamination of the river, the aquifers and the soils of the area from untreated or poorly treated industrial wastewater

5 Industry under examination (2/3) Process inputs: Process outputs: Production process: Fabric rolls: polyester, cotton, viscose, acrylic Dyes: Direct, reactive, acid, disperse, azoic etc. Other textile auxiliaries: acids, salts, bleach, sizing agents, surfactants, stabilisers etc. Water & energy Dyed and finished fabrics Waste effluent Depends on fabric type (natural or synthetic) / quality of the final product Storage of raw material Batching Desizing (cotton textiles) Scouring Bleaching Mercerising (cotton textiles) Dyeing Rinsing Finishing.Wastewater generation...

6 Industry under examination (3/3) Wastewater production: 85 m 3 /d Softening 6% Exhausts from production 2% Personnel 1% 1. Process of washing and dyeing textile substrates 2. Rinsing of equipment in the production process 3. Washing of floors &areas of production and wastewater produced by personnel Steam losses 8% Water consumption Production process 83% Current wastewater treatment method: Wastewater Screening Equalization AS process Flocculation Sedimentation Sand filtration AC filtration Chlorination

7 Pilot Membrane Bioreactor Influent Operation time of blower & permeate suction pump Aeration tank MBR Dewatering unit PLC Treated effluent ph, T, TMP Equalisation tank

8 Membrane module characteristics Parameter Value Type Flat plate Filtration mode Outside In Filtration area (m 2 ) 1 Recommended trans membrane pressure, TMP (mbar) <200 Maximum TMP (mbar) 250 Filter pore size (μm) 0.1 Wastewater treatment capacity (m 3 /d) 0.5 Recommended flux (L/m 2 /h) 20 Membrane construction material PVDF Manufacturer SINAP

9 Experimental period & Sampling Total operating time: 40 days Chemical cleaning of membranes: 21 st day of operation Sampling frequency: 2 times per week Sampling points: Inlet Aeration tank Outlet

10 Operational parameters Mean value Parameter standard deviation Mixed liquor ph Mixed liquor temperature ( o C) DO (mg/l) <0.5 OLR (kgcod/m 3 /d) 0.39 F/M (gcod/gmlvss/d) MLSS (g/l) 7,547 1,692 MLVSS (g/l) 5,278 1,051 HRT (d) 7.5 SRT (d) No sludge wasting Permeate net flux (L/m 2 /h) 8.3 Filtration time during one cycle (min) 8 Relaxation time during one cycle (min) 2

11 Materials & Methods Analytical methods ph & conductivity Total & volatile suspended solids (TSS, VSS) Biochemical Oxygen Demand (BOD 5 ) Standard Methods Chemical Oxygen Demand (COD) Total nitrogen (TN), ammonium (NH 4 N), nitrate (NO 3 N) & nitrite (NO 2 N) Photometry Total phosphorus (TP) & phosphate (PO 4 P) Metals (Cr, Cu, Mn, Ni, Cd, Pb, Zn) Atomic Absorption Spectroscopy Biomass activity tests OUR AUR NUR

12 Results & Discussion Physicochemical characteristics of influent and treated effluent by MBR Parameter Influent (average ± SD) Treated Effluent (average ± SD) ph 8.05 ± ±0.06 Conductivity (ms/cm) 3.03 ± ±0.38 TSS (mg/l) ± ±0.5 VSS (mg/l) ± COD (mg/l) 2966 ± ±47 Soluble COD (mg/l) 1218 ± 351 BOD5 (mg/l) 655 ± ±5.6 TP (mg/l) 2.9 ± ±1.38 PO4 P (mgp/l) 1.73 ± ±0.42 NH4 N (mgn/l) 2.24 ± ±2.16 NO3 N (mgn/l) 2.08 ± ±0.38 TN (mgn/l) 32.1 ± ±5.1 Cu (μg/l) 54 ±25 Mn (μg/l) 15 ±11 Zn (μg/l) 292 ± ±12 Pb (μg/l) <5

13 COD / BOD5 = 4.5 COD= f(t) BOD= f(t) CODin CODout COD removal efficiency, % BODin BODout BOD removal efficiency, % COD (mg/l) % 97% 96% 95% 94% 93% 92% 91% 90% BOD (mg/l) % 100% 98% 96% 94% 92% 90% Day Day

14 30 65 % Nitrogen removal

15 Biomass activity tests Endogenous activity (sourend) Aerobic heterotrophic biomass (sour) Nitrifiers (saur) Denitrifiers (snur) Parameter Average value standard deviation sour endogenous 20 o C (mgo 2 /gvss h) sour max 20 o C (mgo 2 /gvss h) saur 20 o C (mgn/gvss h) snur 20 o C (mgn/gvss h)

16 Trans membrane pressure 800 Chemical cleaning Sodium hypoclorite (2%) Citric acid (0.5%) 700 TMP (mbar) Gradual TMP increase 8 mbar / d Duration of operation (d)

17 Conclusions Τhe removal of both COD and BOD from textile wastewater was high > 90% The low DO in the bioreactor led to simultaneous nitrification/denitrification with nitrogen removal being variable from 30 up to 65% Oxygen uptake rate, nitrification and denitrification rates were much lower than those typically met in municipal wastewater plants. Textile wastewater contains substances that can inhibit biomass activity. However, the activity values are similar to those obtained in other industries (i.e. petrochemical) Severe fouling of the flat plate membranes can be avoided by maintaining the permeate flux at approximately 8 10 L/m 2 h The treated effluent could meet the limit for nitrogen, phosphorus and BOD5 but not for the COD The proposed treatment system is in a preliminary period of operation so longer time is needed to confirm that the effluent quality meets the needs of the specific industry in terms of compliance to the legislative framework

18 Future steps.. Assess the economic viability of the proposed treatment method in relation to the current treatment system of the industry Examine the efficiency of the process under: 1. Lower HRT 2. Increased aeration, which will lead to increased DO concentration.

19 Thank you for your attention! The project is co financed by the European Regional Development Fund (ERDF) of European Union and Greek national funds in the framework of the Operational Program "Competitiveness and Entrepreneurship" of the National Strategic Reference Framework (NSRF ) Research Funding Program: Synergasia Action I. Cooperative small and mid scale projects (project code: 09SYN )