Nutrient Recovery and Microalgae Biomass Production from Human Urine in Membrane Photobioreactor

Ho Chi Minh City University of TechnologyEmail: nguyenvanthuan071@gmail.com Nutrient Recovery and Microalgae Biomass Production from Human Urine in Membrane Photobioreactor Van-Thuan N

Ho Chi Minh City University of Technology

Email: nguyenvanthuan071@gmail.com

Nutrient Recovery and Microalgae Biomass

Production from Human Urine

in Membrane Photobioreactor

Van-Thuan Nguyen * , Thanh-Tin Nguyen, Thi-Thanh-Thuy Ngo, Nguyen-Tra-My Phan

& Xuan-Thanh Bui

1

Application of Microalgae

Reducing CO2

Biofuels production

Wastewater treatment

products

Bio-Why Urine?

Contains the major part of the daily

excretion of N, P, K contributing 88%, 67%

and 73% (Karak & Bhattacharyya, 2011)

- Urine contains a high amount of N & P  eutrophication.

- To rescue a huge amount of nutrient, urine can be used as liquid fertilizer, watering directly or transform into struvite products.

Liquid fertilizer (Watering)

Struvite crystals formationUrine

Characteristics of Human Urine

(Krak & Bhattacharyya,

Microalgae: Chlorella Vulgaris

Microalgae strain: Chlorella Vulgaris

Chlorella Vulgaris

 Able to survive in wastewater (Das, 2011)

 Suitable to grow in the climate of Vietnam (Pulz, 2001)

 Grow in a wide range of salinity

 Able to grow in high concentration of

CO2 (40%) (Das, 2011)

 High yield of oil contents (28-32%) (Chisti, 2007).

Why Sponge MBR technology

• Prevent washout problem of algae;

• Operate at high flow rate & complete retention of biomass;

• Enhance light accessibility, sufficient mixing, easily accessible carbon source  decreasing the costs for construction & operation;

• Independent HRT & MRT  higher biomass productivity, enhance nutrient removal & less footprint requirement

Research Objectives

Methodology

Research Contents

• Microalgae biomass productivity;

• Nutrient recovery from urine.

Flux = 5 LMH HRT = 2 days MRT = 10, 7, 5 days

MPBR Evaluation of biomass growth and nutrient recovery in MPBR

using urine as substrate

Experimental Set-up

Reactor volume = 4 L

Membrane (Mitsubishi, Japan)

 Chlorella vulgaris

Supplied by The Research Institute for Aquaculture No.2, Vietnam

Initial conc = 50 mg/L

Parameter Analysis

 Cell density

Fuchs-Rosenthal & Burker method:

Cell density (cell/mL)= α x 0.25 x 106

Parameters Methods

pH 4500 – H+ B Electrometric Method TKN 4500 – Norg B Macro – Kjeldahl

gauge, PG30, Japan

 Analytical methods

Cell counting!

α: cell number of one large square which

accounted for an average value from 4 large

squares in the chamber One large square contains

16 small squares with the area of 0.0025 mm 2 &

chamber depth of 0.1 mm

Results & Discussion

Biomass Growth

0 500 1000 1500 2000 2500 3000

MRT = 10 days MRT = 7 days MRT = 5 days

Cult ivation (days)

Start-up

2145

1575

2025

- Fast growing in first 10 days  adapt well with human urine feed;

- Average biomass conc = 2025, 2145 & 1575 mg/L (MRT = 10, 7 & 5 d)

 Effectiveness of membrane avoiding biomass wash-out

- Biomass conc reached 2120 mg/L after 10 days (higher results of Honda et al., 2012; Gao et al., 2014)

10 7 5 0

50 100 150 200 250 300

- Shorter MRT with a frequent larger amount of mixed biomass (algae/bacteria/protozoa) withdrawn  less competition of bacteria to microalgae growth  Promoted strong growth

of microalgae.

- Highest productivity at MRT = 5 d

• Most MRTs, protozoa and bacteria was detected

• Less protozoa observed at shorter MRT

Amoeba proteus

Amoeba proteus

Microscopic Observation

Appearance of protozoa

Cell flocculation

Flocs morphology at MRT = 10 days Flocs morphology at MRT = 5 days

Algae Flocs & Morphology

Flocs formation

Rotifer

Microscopic Observation

Appearance of protozoa and flocs formation

• Flocs formation appeared in MPBR after 10 days of cultivation,

• Less protozoa observed at shorter MRT

Rotifer observed under microscope with x40 magnification

Microscopic Observation

10 7 5 0

50 100 150 200 250

0 10 20 30 40 50 60 70

80 Influent TN Effluent TN The average TN removal rate

- Urea was hydrolyzed into ammonia  easily used as a nutrient source.

- Short MRT facilitated higher nitrogen uptake due to higher productivity

- TN removal efficiency was also higher than previous studies

10 7 5 0

2 4 6 8 10 12 14 16

2 2.1 2.2 2.3 2.4 2.5 2.6 2.7

2.8 Influent TP Effluent TP The average TP removal rate

Membrane photobioreactor

Nutrients conc in influent Nutrients loading

Nutrients removal

Wastewater/me mbrane

SVR (m -1 )

TN (mg/L)

TP (mg P /L.d)

TN (mg N/L d)

TP (mg P/L d)

TN (mg N/

L d)

TP (mg P/ L d)

SS (mg/L)

Microalgae productivity (mg/L d)

Marbelia et

al (2014)

Synthetic, MBR permeate (FS) 20

22.1 1.69-2.17

7.48- 11.05

3.74- 1.085

0.845- 4.55

Biomass productivity & nutrient removal using urine as substrate

was observed to be greater compared to other fed wastewaters

Notes: All of above study, Chlorella vulgaris cultivation in previous study

Abbreviations: SVR: surface area to volume ratio; TN: total nitrogen; TP: total phosphorus, SS: suspended solid.

Comparison

Conclusions

- Shorter MRT in MPBR using human urine reduced the inhibition of bacterial competition  thus maintain the better growth of microalgae;

- Short MRT achieved higher biomass conc., biomass productivity, nutrient recovery & algae bioflocculation;

- Biomass production and nutrient removal in MPBR using urine was much higher than those using other wastewaters in previous studies

Concluding Remarks

Research was funded by Heineken – Vietnam:

Thanks for supports from BIOSEP members:

HCMUT, Vietnam: Thi-Thanh-Thuy Ngo, Trung-Tin Vo,

Thi-Thanh-Huyen Nguyen, Thi-Hang Nguyen.

ENSIL, France: Hugo Dadu, EPFL, Switzerland: Alexander Marcos.

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A study by Rawiwan Boonchai and Gyutae Seo (2015) have compared based on the value of flux 3 42; 58.5; 70.5 and 103.5 L/m2/h with concentration Chlorella sp 1000 mg/l using MF membrane systems found the rate of increase corresponding TMP 0.12; 0.19; 0.41 and 1.03 Increased TMP speed can be defined as the speed and results dirty film speed slightly soiled membrane flux value below 58.5 L / m2 / h.