IWA Nutrient Removal and Recovery 2015: moving innovation into practice MAY 18-21, 2015 GDAŃSK, POLAND

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1 Palasantza * Panagiota-Aikaterini, Germanidis * Georgios, Tolkou ** Athanasia, Mitrakas *** Manassis, Kalaitzidou *** Kyriaki, Raptopoulou ** Christina, Tsimpoukas * Nikolaos, Noula * Katerina, Zouboulis ** Anastasios *AKTOR S.A., Wastewater Treatment Plant of Touristic Area of Thessaloniki AINEIA, N. Michaniona, Thessaloniki, Greece ** Department of Chemistry, Aristotle University of Thessaloniki, Greece *** Department of Chemical Engineering, Aristotle University of Thessaloniki, Greece GDAŃSK, 20 May, 2015

2 Essential for life Limited, non-renewable, non-substitutable resource Responsible for eutrophication Phosphorus recovery Found in geological deposits of phosphate (phosphate rock) Anthropogenic P is now often much greater than natural inputs of P in many watersheds Sewage, agriculture, etc.

3 The wastewater treatment industry uses several methods to remove phosphorus such as: enhanced biological phosphorus removal processes, coagulation/flocculation, chemical precipitation, membrane purification, or adsorption easy implementation and functioning, applicability at low concentrations, potential for both batch and continuous processes and potential for adsorbent regeneration

4 Influent: 8x10 3 m 3 /d municipal waste water: 7x10 3 m 3 /d Domestic septage waste: 1x10 3 m 3 /d Conventional preliminary, primary, secondary treatment and ozone disinfection The secondary effluent has a concentration of 6 mg P-PO 4 /L Disposal regulation P-limit in WWTP "AINEIA": 12 mg P-PO 4 /L

5 This study s challenging part was to scale-up the appropriate recovery treatment schema of phosphorous, from lab to full-scale. Continuous flow adsorption experiments were conducted for PO 4 removal from secondary effluent at a temperature of 20±1 o C and ph= 7.0, by using FeOOH adsorbents. Various commercially available iron based adsorbents (GFH, Bayoxide, AquaAsZero) were investigated. Table 1 Commercial information of FeOOH used. Adsorbent Chemical formula Supplier AquAsZero Schwertmannite Loufakis Chemicals, Greece GFH, Granular Ferric Hydroxide Akaganeite (β-feooh) Siemens (Germany) Bayoxide Goethite (α-feooh) Bayer (Germany)

6 In order to investigate the adsorption capacity of FeOOH, dynamic continuous flow adsorption experiments were conducted for PO 4 removal at a ph value 7.0, by implementation of Rapid Small Scale Column Tests (RSSCTs). This rapid small-scale column test (RSSCT) ran at a flow rate of 400 ml/h effluent and employing an empty bed contact time (EBCT) 3 min at a temperature of 20 ± 1 o C and ph=7.7±0.1, by using iron oxy-hydroxides (FeOOH) as absorbent. Saturated adsorbents were regenerated by a NaOH solution with concentration ranging between N for AquAsZero and ~1N for GFH. PO 4 was recovered from regeneration solution as calcium salts. Figure 1. Continuous configuration of Rapid Small Scale Column Tests (RSSCTs)

7 ADSORPTION- RSSCTs Figure 2. Adsorption capacity of iron oxyhydroxide (FeOOH) used for phosphate removal. 5 mg P-PO 4 /g FeOOH for AquAsZero 4.8 mg P-PO 4 /g FeOOH for GFH 6.5 mg P-PO 4 /g FeOOH for Bayoxide 11.8 mg P-PO 4 /g FeOOH for lab FeOOH Figure 3. Breakthrough curves of RSSCTs for 4 sequential cycles of AquAsZero The adsorption capacity was gradually stabilized to 2.8 mg P-PO 4 /g FeOOH after 4 regeneration cycles

8 REGENERATION- RSSCTs The regeneration at ph value 12.5 resulted in the efficient phosphate recovery within 2h. The regeneration solution was enriched in higher than 100 mg P- PO 4 /L. The phosphates were precipitated as calcium phosphate salt by addition of Ca(OH) 2 solution. Figure 4. Profile of PO 4 concentration in regeneration solution by the addition of (alkaline) NaOH solution.. The phosphate content in the recovered solids was 48±4% w/w.

9 Following the RSSCTs experience a pilotplant working in continuous flow mode was designed and built to treat L/h.

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11 PLC fully automatic operation SCADA

12 Feed of the pilot plant and microfiltration by hollow fibres membranes for retaining the solids. Phosphate adsorption onto FeMnOOH adsorbent was taken place by using a fixed bed working with an Empty Bed Contact Time (EBCT) 10 min.

13 Phosphate recovery from the regeneration stream was performed by adding chemical reagents to form precipitate. The separation of precipitate (as calcium or magnesium phosphate solids) was performed by microfiltration membranes, following by the dehydration of precipitate. The regeneration process works with ph in the range of

14 Ce P-PO4, mg/l IWA Nutrient Removal and Recovery 2015: RESULTS- PILOT PLANT Column: PVC Ø 200,Η = 2,000 mm, Hsorbent : 120 cm, volume: 31.9 L, surface: m 2 Adsorbent AquAsZero FeMn (FeMnOOH): quantity: 23 kg, size of granules: mm (mean, 0.63mm) Feeding Conditions Influent Concentration P-PO 4-3 (mg/l): (average value: 2.5 ) Average flow rate: 186 L/h Adsorption capacity: 6.6 mg P-PO 4 /g FeMnOOH AquAsZero FeMn Adsorption capacity (q), mg P-PO 4 /mg Figure 5. Adsorption capacity of iron manganese oxy-hydroxide (FeMnOOH-AquAsZero) adsorbent used for phosphate removal by continuous feeding of secondary treated wastewater effluent from the WWTP AINEIA

15 Conclusions In this study, the secondary effluent of AINEIA s municipal wastewater treatment plant, established in N. Michaniona-Thessaloniki, in Northern Greece, was treated for phosphates removal and recovery. RSSCTs adsorption experiments were conducted for PO 4 removal at ph=7.0, by using FeOOH, such as the GFH, Bayoxide, AquaAsZero and laboratory synthesized FeOOH. The regeneration solution was enriched in phosphates (>100 mg PO 4 /L). Phosphates were precipitated as calcium phosphate salt by the addition of Ca(OH) 2 solution. Following the RSSCTs experiments a pilot-plant, working in continuous flow mode, was designed and built to treat L/h. The adsorption capacity of iron manganese oxy-hydroxide (FeMnOOH) adsorbent has so far reached at 6.6 mg P-PO 4 /g FeMnOOH and the regeneration will follow when the residual concentration exceeds the value of 1 mg P-PO 4 /L (the strict regulation limit for WW disposal).

16 Acknowledgements The financial support through the co-financed by the European Union and the Greek State Program PAVET, Project (PhoReSe)- Recovery of Phosphorus from the Secondary Effluent of Municipal Wastewater Treatment, is gratefully appreciated. This research project was supported by the approval of EYATh's S.A.-Department of Plants' Operation, Maintenance & Environmental Monitoring, which is gratefully appreciated.

17 Thank you for your attention Palasantza*Panagiota- Aikaterini AKTOR S.A. GDAŃSK, 20 May, 2015