The Effect Of Light-Emitting Diodes (LEDs) Light Intensity on High Rate Algal

Reactor System In Laundry Wastewater Treatment

Adhi Triatmojo a, *, Bieby Voijant Tangahu a

a Department of Environmental Engineering, Institut Teknologi Sepuluh Nopember,

Indonesia

* Corresponding author.

E-mail address: triatmojoadhi@gmail.com

1

1

2

3

4

5

6

7

8

9

10

1112131415

12

ABSTRACT

Laundry wastewater contain nutrients with high concentration. Nutrients commonly found in

laundry wastewater are nitrogen and phosphorus. One of the technology for wastewater

processing with high nutrient content is by using High Rate Algal Pond (HRAP). This study

has a purpose to determine the effect of duration and intensity of light for the removal of

Chemical Oxygen Demand, Nitrogen-ammonia, and Phosphate content.

This study was conducted to assess the exposure of light that has greater efficiency for

nutrient removal in laundry wastewater in the HRAP system. The microalgae used is

Chlorella Vulgaris that can grow in polluted environments and suitable for use in wastewater

processing. Variable that being used light intensity of 2000-3000 Lux, 4000-5000 Lux, and

6000-7000 Lux to determine the most efficient intensity in nutrient removal. Parameters to be

tested in this study were Chemical Oxygen Demand, Nitrogen-ammonia, Phosphate to

determine the efficiency of nutrient removal and Chlorophyll α to determine the conditions of

Microalgae development.

The results showed that the greatest ability for nutrient removal was the reactor duration of

24 hours light exposure with light intensity 6000-7000 Lux is able to remove 54.63% of

Chemical Oxygen Demand, 41.60% of Nitrogen-Ammonia and 15.16% of Phosphate. Based

on the result of statistic test, the variable of light intensity significantly influence the removal

efficiency of Chemical Oxygen Demand and Nitrogen-Ammonia shown With P-value value

<5%.

Keywords: High Rate Algal Pond, Laundry Wastewater, Light Intensity, Light-Emitting

Diodes, Microalgae.

2

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

34

1. Introduction

As the population increases, the wastewater generated by human activities is increasing,

environmental pollution by liquid waste in Indonesia resulted in the decrease of river water

body water quality. According to BLH [2] the water quality decline is caused by domestic

waste that contribute to contamination by 60% and industrial waste by 40%. Tectona found

that [11] laundry business is one of the businesses that require clean water and produce a lot

of wastewater, so if the wastewater is not processed first it can lead to eutrophication and

explosion of algae. On similar research Ciabatti [4] resulted in water needs for laundry

industry average 15 Liter / kg laundry clothes, average laundry industry per day wash 25 kg

of clothes so as to produce waste water about 400 Liter / day. Laundry waste is one of the

causes of algae blooming in water bodies because it has high organic content and nutrient

concentrations that can support the growth of microalgae.

One of the urban wastewater treatment systems using algae usually aims to reduce the levels

of nutrients. The development and application of a processing system capable of lowering the

levels of organic substances as well as nitrogen such as High Rate Algal Pond is very

important to ensure the maintenance of water bodies quality according to Garcia et., al. [5].

The assimilation of N by algae and floating aquatic plants accounted for about 65% of total N

decrease, ammonia volatilization of 15% and about 20% total decrease in N content can be

assumed based on nitrification-denitrification process concluded by Mostret et al., [10]. In

2010, Wang's [13] research on the utilization of mixed algae for domestic wastewater

treatment and biodiesel feedstock, from the research obtained the efficiency of allowance N

of 92-95% and P by 62-80%. HRAP is one of the treatment that can be applied in Indonesia

to reduce laundry wastewater nutrient. HRAP has an advantage over procurement,

operational and maintenance costs that are relatively cheaper and easier than other methods

3

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

62

63

64

65

56

from Garcia [5]. According to Wang's [13] research specific use of algae may allow for

greater nutrient removal, in addition to specific species biomass byproducts for various

purposes. In research about usage of microalgae Man [8] suggested that Chlorella Sp. is a

type of algae that has tolerance levels of pollutants are quite good and easy to obtain, so

Chlorella Sp. is often used in wastewater treatment.

This study tested the decrease of nutrient content in polluted water waste waste by using High

Rate Algal Reactor (HRAR), with variation of light intensity to know the efficiency of

decrease of nutrient content, and the development of alga yielded. HRAR are performed at

detention time of 6 days with variation of light intensity 2000-3000 Lux, 4000-5000 Lux, and

6000-7000 Lux. Removal efficiency of each reactor will be analyzed ability in decreasing

parameters of COD, nitrogen-ammonia, and phosphate, Chlorophyll α will be analyzed to

comprehend the microalgae development. In Photobioreactor the growth of microalgae will

be equal as the light intensity, using fluorescent lamp light intensity compatible are 2000 Lux

till 12000 Lux Masaki et al., 2015 [8]. Using Light Intensity from LEDS lamp for microalgae

above 7000 Lux can resulted in photoinhibition, where microalgae growth will be inhibited

Ifeanyi [6].

2. Materials and methods

2.1. Collection of Sample

At the beginning of the research, laundry wastewater are analyzed with COD, Ammonia,

and Phosphate as the parameters. Sampling is done in Keputih District Sukolilo with

Integrated Sample method on 4 Different Laundry Enterprises. The results showed that

COD and phosphate values were ranged between 600-829 mg/L and 8,53-12,62 mg/L.

4

66

67

68

69

70

71

72

73

74

75

76

77

78

79

80

81

82

83

84

85

86

87

88

89

90

78

2.2. Materials and Medium

This experiment uses 6 reactor containers consisting of 3 test reactor containers and 3

containers of control reactors, the volume of reactor that being used is ± 12 Liter with

dimension of diameter 30 cm and 27 cm height. Lighting sources used are the Light

Emitting Diodes 18 watt Phillips Brand, the light intensity are measured using the Lux

Meter HS1010 on the surface of the reactor. The algae used in this study was Chlorella

vulgaris previously filtered with a 50 μ cloth filter, the use of cloth filter to harvest

microalgae has an efficiency of 94 ± 2% Bejor [1].

2.3. Determination of The Effect of Light Intensity on High Rate Algal Reactor

Nitrogen-Ammonia was analyzed by using Nesslerization Method by means of absorbance

readings using spectrophotometer. Phosphate in orthophosphate form was analyzed using

4500-P Stannous Chloride Methode method using Ammonium Molybdate and absorbance

readings using a spectrophotometer. COD (Chemical Oxygen Demand) analysis was

performed by using the close reflux method and FAS (Ferrous Amommonium Sulfate)

solution to determine the COD content found in the reactor.

Chlorella Vulgaris was illuminated by Light Emitting Diodes with variety of light

intensity 2000-3000 Lux, 4000-5000 Lux, and 6000-7000 Lux. The reactor detention time

is 6 days with constant agitation. Removal efficiency of each reactor will be analyzed

through the removal parameters of COD, nitrogen-ammonia, and phosphate. Chlorophyll

α will be analyzed to comprehend the microalgae development.

3. Results and discussion

3.1. Nitrogen-Ammonia Removal

5

91

92

93

94

95

96

97

98

99

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

910

The light intensity experiment showed that 6000-7000 Lux was adequate for algal

growth. This observation was in line with the report of Ifeanyi et. al. [6] who reported that

light with higher intensity can boost the growth of algae. The growth of algae in reactor

can affect HRAR (High Rate Algal Reactor) nutrient removal efficiency Lilliana [7], the

higher light intensity can make microalgae concentration higher, so the better removal

efficiency will become. The rate of Ammonia removal in all batch reactor increased at

higher light intensity as can be seen on Figure 1 and Figure 2. A linear correlation

between chlorophyll α and ammonia concentration in the reactor was observed for the

experiments. It is suggested that the ammonia are consumed by microalgae.

Fig 1. HRAR Ammonia Trend

Fig 2. HRAR Ammonia Removal

It is seen that the ammonia content range always decreases, but on day 3 and 4 ammonia

returns up, after that the trend on the next day continues to fall. This is due to the 3rd and 4th

6

116

117

118

119

120

121

122

123

124

125

126

127128129

130

131

1112

days some of the microalgae present in the reactor begin to die and decompose thus releasing

the nitrogen back into the reactor. The optimum removal efficiency is in the reactor with

6000-7000 Lux lighting which is 50%, while the 4000-5000 Lux and 2000-3000 Lux reactors

have 32% and 26% removal efficiency. The control reactor has a lower efficiency than the

reactor containing the microalgae. The range of removal at the control reactor ranged from

21-39%, while the reactor containing microalgae of N-ammonia removal ranged from 58-

73%. This suggests that the uptake of microalgae greatly affects the N-ammonia removal

process, because in general ammonia is the easiest nitrogen source to uptake by microalgae

Garcia [4].

3.2. HRAR Phosphate Removal

When correlating the removal percentage of phosphate with light intensity, the correlation

coefficients were low as we can see at Figure 3 and Figure 4. This suggested that factors

other than uptake from microalgae can be at play. The mechanism that plays an important

role in the reduction of phosphate concentration is immobilization in the sediment with the

precipitation of phosphorus-calcium and uptake bonds by microalgae Chen [3] .

Fig 3. HRAR Phosphate Trend

7

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

1314

Fig 4. HRAR Phosphate Removal

Figure 3 shows that the overall phosphate concentration is decreasing. The phosphate

concentration in the reactor tends to fluctuate, it could be because the microalgae in the

reactor metabolize so as to express the waste Vymazal [12]. Then in Figure 4 can be seen the

efficiency of removal from 24-hour lighting reactor. Reactor with intensity 4000-5000 has a

provision of 30%, while 6000-7000 Lux has a percentage that is not much different that is

27%. Reactor with intensity 2000-3000 has the lowest percentage of allowance that is 7%. On

the graph it is seen that the removal efficiency at the control reactor has the greatest

allowance efficiency of 19-36%. The phosphate removal agent is smaller when compared to

N-ammonia, that is because according to the redfield ratio the C: N: P requirement for

microalgae growth is 106: 16: 1 thus uptake phosphate by microalgae will be smaller.

3.3. HRAR Phosphate Removal

Correlation between Chemical Oxygen Demand and light intensity are linear as shown in

Figure 5 and Figure 6. In the reactor 2000-3000 Lux trend of COD concentration continues to

decline and tend to be stable until the end of residence time, In the reactor 4000-5000 Lux

and 6000-7000 Lux concentration increase occurred on day 2 and to 3. Fluctuations in

concentration occurs due to dead microalgae will decompose And counted as organic

substances dissolved in wastewater.

8

150151152

153

154

155

156

157

158

159

160

161

162

163164

165

166

167

168

169

170

1516

Fig 5. HRAR Chemical Oxygen Demand Trend

Fig 6. HRAR Chemical Oxygen Demand RemovalFigure 6 shows that sequentially the 6000-7000 Lux, 4000-5000 Lux, and 2000-3000 Lux

reactors have 42%, 37%, and 35% removal percentages respectively. The greater the intensity

of light, the greater the percentage of COD removal. This is due to the amount of light

intensity that affects the amount of microalgae requiring organic substances to breed.

4. Conclusions

The intensity of light has a significant effect on the removal of Ammonia and Chemical

Oxygen Demand. It is proved by ANOVA statistic test that has P value <5%, light intensity is

proportional to percent nutrient removal. Phosphate is not significantly affected by light

intensity, this result is proved by ANOVA statistic test which shows P-value> 5%. The

largest removal percentage for COD is 55%, and Ammonia is 46% with light intensity of

6000-7000 Lux, whilst phosphate has 30% with light intensity of 4000-5000 Lux. In this

9

171

172

173174175

176

177

178

179180

181

182

183

184

185

186

1718

work, the effects of light intensity on dissolved ammonia, phospate, and chemical oxygen

demand removal, microalgal growth were studied. From the knowledge obtained, this algal

species can be improved for field trial possibly for bioremediation purpose.

Acknowledgement(s)

The authors are grateful to the LPPM ITS institution for their financial support. In addition

we are grateful to the Environmental Engineering FTSLK ITS for their technical cooperation

and provision of chemical compounds.

References

[1] Bejor E. S., C. Mota, N.M. Ogarekpe, K. U. Emerson, J. Ukpata. 2013. Low-Cost

Harvesting of Microalgae Biomass From Water. International Journal of Development

and Sustainability, Volume 2 Number 1 (2013): Pages 1-11.

[2] BLH. 2010. Kualitas Air Surabaya Mengalami Penurunan.

http://lh.surabaya.go.id/weblh/?c=main&m=detail&id=35, Accessed in 5 September 2016

at 13.33.

[3] Chen. P., Zhou, Q., Paing, J., Le, H. dan Picot, B. 2003. Nutrient Removal by Integrated

use of High Rate Algal Ponds and Macrophytes system in China. Water Science and

Technology, 48(2), 251-257.

[4] Ciabatti, I. F., L. Faralli, E. Fatrella dan F. Togotti. 2009. Demonstration of Treatment

System for Purification and Reuse of Laundry Wastewater. Bioresource Technology, 99.

[5] Garcia, J., Mujeriego, R. dan Marine, M.H. 2000. High Rate Algal Pond Operating

Strategis for Urban Wastewater Nitrogen Penyisihan. Journal of Applied Phycology,

12(3), 331-339.

[6] Ifeanyi V.O., Anyanwu B.N., Ogbulie J.N., Nwabueze R.N., Ekezie W., and Lawal

O.S.2011.Determination of the effect of light and salt concentrations on Aphanocapsa

algal population, African Journal of Microbiology Research 5 (17): 2488-2492.

10

187

188

189

190

191

192

193

194

195

196

197

198

199

200

201

202

203

204

205

206

207

208

209

210

211

1920

[7] Liliana Delgadillo-Mirquez, Behnam Taidi, Dominique Pareau, Filipa Lopes. 2016.

Nitrogen and Phosphate Removal from Wastewater with a Mixed Microalgae and

Bacteria Culture. Biotechnology Reports 11 (2016) 18-26.

[8] Man K. L., M. I. Yusoff, Y. Uemura, J. Wei. 2016. Cultivation of Chlorella vulgaris using

nutriens source from domestic wastewater for biodiesel production: Growth condition and

kinetic studies. Renewable Energy (103) 197-207.

[9] Masaki, Ota, Motohiro T., Yoshiyuki S., R. Lee Smith Jr., H. Inomata. 2015. Effects of

light intensity and temperature on photoautotrophic growth of a green microalga,

Chlorococcum littorale. Biotechnology Reports Volume 7, September 2015, Pages 24–29.

[10] Mostret, E.S., dan Grobbelar, J.U. 1987. The Influence of Nitrogen and Phosphorus on

Algal Growth and Quality in Outdoor Mass Algal Culture. Biomass, 13(4) 219-233.

[11] Tectona, Johan. 2011. Pemanfaatan Kayu Angsana (Pterocarpus Indicus) Sebagai Arang

Aktif untuk Pengolahan Limbah Laundry. Tugas Akhir S1, Jurusan Teknik Lingkungan

FTSP ITS, Surabaya.

[12] Vymazal, J., 1995. Algae and Element Cycling in Wetlands.

[13] Wang LA, Min M, Li YC, Chen P, Chen YF, Liu YH, et al. 2010. Cultivation of green

algae Chlorella sp. in different wastewaters from municipal wastewater treatment plant.

Appl Biochem Biotechnol 2010;162:1174–86.

11

212

213

214

215

216

217

218

219

220

221

222

223

224

225

226

227

228

229

230

231

232

233

234

235

236

2122

Table 1

Your title should be above the table.

C/Cu Copper size (nm) Shell R (Ǻ) CN σ2 (Ǻ2)

6 12 Cu-Cu 2.54 6.4 0.0089 10 Cu-Cu 2.54 4 0.00812 8 Cu-Cu 2.54 3.8 0.00915 7 Cu-Cu 2.55 3.9 0.009

12

237

238

239

240

241

242

243

244

245

246

247248

249250251252253254255256257258259260261262263264265266267268269270

2324

Fig. 1. The caption should be below the figure.

13

271272273274275276277278279280281282

283

284

2526