Intensification of Algal Bioprocesses for Nutrient Recovery from Wastewaters

Transcription

1 Intensification of Algal Bioprocesses for Nutrient Recovery from Wastewaters Jeremy Guest Assistant Professor Civil & Environmental Engineering University of Illinois at Urbana-Champaign 68th Annual KU Environmental Engineering Conference Lawrence, KS April 18, 2018

2

3 We may often think of algae as a potential risk to public and environmental health. [green-blog.org] [

4 We may often think of algae as a potential risk to public and environmental health. cyanobacteria in Lake Erie near the drinking water intake for Toledo, Ohio [toledoblade.com; 2014 water crisis] Note: Algae are eukaryotes. Cyanobacteria are often referred to as blue-green algae, but they are not algae. They are bacteria.

5 We may often think of algae as a potential risk to public and environmental health. [toledoblade.com; 2014 water crisis] the cyanobacteria bloom resulted in high concentrations of microcystin, a chemical that can damage the liver.

6 Or perhaps we think of algae as a nuisance algae on secondary clarifier weirs can slough off and interfere with water quality measurements. [Kuldip Kumar, Metropolitan Water Reclamation District of Greater Chicago]

7 Today we ll discuss the development of suspended growth algal processes for wastewater treatment. traditional design and use of algal systems intensification of algal systems for nutrient recovery recent findings and & emerging trends in algal processes

8 Phototrophs have traditionally been used in low intensity, large footprint systems like ponds or lagoons.

9 Wastewater ponds/lagoons are some of the most common technologies for small utilities. In the U.S. in the year 2000: ~16,255 Publicly Owned Treatment Works (POTWs) ~ half (50.3%) included ponds/lagoons ~ half (49.7%) with no ponds/lagoons [Data from Robert Bastian, US EPA; Algae Biomass Summit (ABS) Presentation, October 2016, Pheonix, AZ.]

10 The objective for microalgae in stabilization ponds has been to provide oxygen for BOD removal (and nitrification). [Oswald and Gotaas (1957) Proc. Am. Soc. Civil Engrs., Separate; 686.]

11 Algae growth was largely incidental. Make the pond large and shallow, and algae will come (in low concentrations).

12 Design standards for ponds are empirical, based on depth and hydraulic retention time (HRT). anaerobic facultative [Rich, Unit Processes of Sanitary Engineering, 1963] aerated maturation (tertiary)

13 Design standards for ponds are empirical, based on depth and hydraulic retention time (HRT). function depth HRT anaerobic cbod removal 2-5 m > 1 day facultative cbod removal m > 4 days aerated cbod removal nitrification varies varies maturation (tertiary) cbod removal nitrification m > 3 days [Tchobanoglous et al., Wastewater Engineering: Treatment and Resource Recovery, 2014] [Mihelcic et al., Field Guide to Environmental Engineering for Development Workers, 2009]

14 These low(er) cost systems have been effective for many utilities with low flow and adequate land. [maps.google.com]

15 but conventional ponds simply haven t evolved to meet the needs of many utilities. requirements for broader adoption of algal technologies these objectives not met by ponds reliable, resilient treatment despite influent microbes and changes in weather, wastewater composition & flow, etc., MUST meet permits small footprint financially viable with manageable risk profile nutrient removal or recovery [maps.google.com]

16 Intensification may make the technology a viable alternative for more utilities. low intensity large footprint medium intensity medium footprint [et.byu.edu] high intensity small footprint [maps.google.com] [Clearas Water Recovery]

17 Two things to keep in mind for intensification: (i) algae achieve nutrient removal via growth and (ii) they can remove many forms of N and P. N and P uptake via assimilation N P

18 Two things to keep in mind for intensification: (i) algae achieve nutrient removal via growth and (ii) they can remove many forms of N and P. N and P uptake via assimilation N P access organic N/P [Qin et al. (2015) Sci. Total Environ. 511, ]

19 Today we ll discuss the development of suspended growth algal processes for wastewater treatment. traditional design and use of algal systems intensification of algal systems for nutrient recovery recent findings and & emerging trends in algal processes

20 To address needs for nutrient removal, algal turf scrubbers have been around for decades. [hydromentia.com] [Adey, W.H. et al. Bioscience (2011) 61(6), ] 20

21 Attached growth systems are mostly at the scale of a single greenhouse. [

22 In general, suspended growth phototrophic systems with good mixing achieve better treatment. [Shoener et al. (2014) Environmental Science: Processes & Impacts; 16(6): ] HRAP - high rate algal pond (suspended) PBR - photobioreactor (suspended) Stirred Tank - stirred tank reactor (suspended) WSP - waste stabilization pond (suspended) ATS - algal turf scrubber (attached)

23 Recent efforts to intensify algal processes and achieve nutrient removal still rely on conventional assumptions. typical assumptions HRT = SRT fixed N:P ratios Redfield ratio C106N16P N:P = 16:1 we cannot control what grows no solid-liquid separation to retain biomass in the system or species-specific N:P it s just a bloom

24 High rate algal ponds achieve more rapid nutrient recovery (relative to unmixed ponds). [et.byu.edu]

25 High rate algal ponds are the most common approach to intensification of suspended growth processes. pilot-scale plant recently built in Cadiz, Spain. [Frank Rogalla, Aqualia; ABS Presentation, October 2016]

26 Small-scale high rate algal ponds are also being tested at pilot-scale at treatment plants in the U.S. [microbioengineering.com/products]

27 Photobioreactors can further intensify treatment and have been pursued at pilot-scale. [chemicals-technology.com] [sardi.sa.gov.au] [Rodolfi et al., Biotech Bioeng 102(1), 2009] [bae.uky.edu]

28 At least one photobioreactor system will be operating at full-scale in the United States in 2019.

29 Intensification is being enabled by solid-liquid separation using membranes.

30 These processes have the potential to achieve tertiary or sidestream nutrient recovery. Tertiary Treatment

31 These processes have the potential to achieve tertiary or sidestream nutrient recovery. Tertiary Treatment Sidestream Treatment

32 Today we ll discuss the development of suspended growth algal processes for wastewater treatment. traditional design and use of algal systems intensification of algal systems for nutrient recovery recent findings and & emerging trends in algal processes

33 Our approach to the intensification of algal processes is to challenge all of these assumptions. typical assumptions HRT = SRT fixed N:P ratios Redfield ratio C106N16P N:P = 16:1 we cannot control what grows no solid-liquid separation to retain biomass in the system or species-specific N:P it s just a bloom

34 Our approach to the intensification of algal processes is to challenge all of these assumptions. HRT = SRT typical assumptions fixed N:P ratios we cannot control what grows HRT << SRT opportunities for innovation N:P is dependent on species & growth rate selective pressures can enable reliability [Terry et al. (1985) J. Phycol. 21, ; Ågren (2004) Ecol. Lett. 7, ]

35 We conduct experimental studies with real and synthetic wastewater, pure and mixed cultures, etc. 35

36 We conduct experimental studies with real and synthetic wastewater, pure and mixed cultures, etc.

37 1st thing to know: The N:P uptake ratio of algae can be influenced by controlling growth rate (via solids residence time, SRT). [Gardner-Dale, D.A.; Bradley, I.M.; Guest, J.S. Influence of solids residence time and carbon storage on nitrogen and phosphorus recovery by microalgae across diel cycles. Water Research, 2017, 121: ]

38 2nd thing to know: Algae can take up nutrients at night by using intracellular, stored organic carbon. [Gardner-Dale, D.A.; Bradley, I.M.; Guest, J.S. Influence of solids residence time and carbon storage on nitrogen and phosphorus recovery by microalgae across diel cycles. Water Research, 2017, 121: ]

39 3rd thing to know: You may be able to achieve reliable performance with your local algae. Illinois North Carolina Florida [Fedders, A.C.; DeBellis, J.L.; Bradley, I.M.; Sevillano-Rivera, M.C.; Pinto, A.J.; Guest, J.S. Comparable nutrient uptake across diel cycles from three distinct algal communities. Submitted] 39

40 4th thing to know: We will be able to model algae just as well as every other wastewater treatment process. [Guest, J.S.; van Loosdrecht, M.C.M.; Skerlos, S.J.; Love, N.G. A lumped pathway metabolic model of organic carbon accumulation and mobilization by the alga Chlamydomonas reinhardtii. Environmental Science & Technology, 2013, 47(7), ] 41

41 4th thing to know: We will be able to model algae just as well as every other wastewater treatment process. use whole-plant, dynamic models ASMs, ADM1, Mantis, phys-chem models add in algal unit processes with the phototrophic process model (PPM) [Guest, J.S.; van Loosdrecht, M.C.M.; Skerlos, S.J.; Love, N.G. A lumped pathway metabolic model of organic carbon accumulation and mobilization by the alga Chlamydomonas reinhardtii. Environmental Science & Technology, 2013, 47(7), ] [Shoener et al. (Work in progress).] 42

42 To summarize our recent findings: there s a bright future for intensive algal treatment processes. We will tailor N:P uptake to match your wastewater achieve 24-hr nutrient uptake via stored carbon leverage local algae model these processes and their integration into the plant

43 There s a bright future for intensive algal treatment processes. tertiary sidestream In the not-to-distant future, you ll be able to: tailor N:P uptake to match your wastewater achieve 24-hr nutrient uptake via stored carbon leverage local algae model these processes and their integration into the plant Jeremy Guest, Assistant Professor jsguest@illinois.edu