840
© IWA Publishing 2014 Water Science & Technology
|
69.4
|
2014
Ammonium reduction from piggery wastewater using immobilized ammonium-reducing bacteria with a full-scale sequencing batch reactor on farm Jung-Jeng Su, Yuan-Chie Chang and Shun-Ming Huang
ABSTRACT This work aims to evaluate the efficiency of ammonium removal from piggery wastewater by an intermittent aeration (IA) sequencing batch reactor (SBR) with immobilized
NHþ 4 -reducing
bacteria
under mesophilic conditions. When a 20-L bench-scale SBR with 11% (v/v) of alginate beads þ containing NHþ 4 -reducing bacteria was used, removal efficiency of NH4 was 63% after 240 h. When a
full-scale SBR system (available volume ¼ 83 m3) with 0.1% (v/v) of alginate-coated light-expanded þ clay aggregates beads containing NHþ 4 -reducing bacteria was used, removal efficiency of NH4 by the
full-scale intermittent aeration SBR (IA-SBR) was significantly different from both traditional intermittent aeration SBR (T-SBR) and the continuous aeration SBR with AL beads containing
Jung-Jeng Su (corresponding author) Yuan-Chie Chang Shun-Ming Huang Department of Animal Science and Technology, National Taiwan University, Taipei, Taiwan and Bioenergy Research Center, National Taiwan University, Taipei, Taiwan E-mail: [email protected]
NHþ 4 -reducing bacteria (P < 0.05). In summary, the IA-SBR with AL beads can significantly promote removal efficiency of NHþ 4 on farm. Key words
| aerobic denitrifier, ammonium removal, heterotrophic nitrifier, piggery wastewater, sequencing batch reactor
INTRODUCTION The conventional method of treating piggery wastewater in Taiwan is the three-step piggery wastewater treatment system, involving solid/liquid separation, anaerobic treatment, and aerobic treatment (Su et al. a). The removal efficiency of total Kjeldahl nitrogen (TKN) ranged from 42.5 to 71.1% year round using a full-scale sequencing batch reactor (SBR) system on a 500-head pig farm (Su et al. ). The higher the atmospheric temperature, the better TKN removal efficiency can be achieved. Lin’s experimental results showed that the removal efficiency of chemical oxygen demand (COD) and total nitrogen (TN) was >70 and 8%, respectively in continuous aeration (CA) mode under a hydraulic retention time (HRT) of 10 days. However, the removal efficiency of COD and TN was 85 and 46%, respectively in intermittent aeration (IA) mode with 50% aeration duration to cycle time under the same HRT (Lin et al. ). Ammonium formed from the anaerobic treatment process can be removed by means of oxidation of ammonium and reduction of nitrate and nitrite using a full-scale SBR
doi: 10.2166/wst.2013.787
system with intermittent aeration (Su et al. b, ). Ammonium and nitrate can be effectively removed by immobilized heterotrophic nitrifying and aerobic denitrifying bacteria with intermittent aeration process. The removal rate of nitrate was 0.032 mmole NO 3 -N/g-cell/h by the aerobic denitrifying bacteria (Pseudomonas alcaligenes strain SU2) under aerobic conditions (Su et al. a, b). Furthermore, the removal rate of ammonium was 1.75 mmol NHþ 4 /g-cell/h by the aerobic denitrifying bacteria (P. stutzeri strain SU3) under limited aerobic conditions (Su et al. ). Alginate is commonly used for entrapment of any types of cell such as bacteria, yeast, fungi, and eukaryotic cells (Nussinovitch ). Alginate gels in the presence of divalent cations [e.g. 2þ Ba þ 2NaþAlg ! Ba2þ(Alg)2 þ 2Naþ] can be heat treated without melting. Gelling depends on ion binding, Ba2þ > Sr2þ > Zn2þ > Ca2þ ≫ Mg2þ, with the control of cation addition (Reis et al. ). The main goal of this study was to evaluate the removal efficiency of carbon and ammonium using alginate-light-expanded clay aggregates
841
J.-J. Su et al.
|
Ammonium reduction by full-scale SBR with intermittent aeration
(LECA) beads coated with co-immobilized bacterial cells in a full-scale SBR system of a commercial pig farm. All removal efficiency of carbon and ammonium as well as the costs of construction and operation were counted for economic analysis.
MATERIALS AND METHODS Microorganisms The NHþ 4 -reducing bacterial strains, P. stutzeri SU2 and P. alcaligenes SU3 were isolated from the piggery sludge of commercial pig farms in Taiwan. Pseudomonas stutzeri SU2 is an aerobic denitrifying bacterial strain and P. alcaligenes SU3 is a heterotrophic nitrifying bacterial strain (Su et al. a, b, c, ). Both strains SU2 and SU3 were used as NHþ 4 -reducing agents for this study. Bio-carrier for microorganisms The bio-carrier was LECAs and previously applied to the biogas bio-desulfurization system (Su et al. , ). LECA consists of small, lightweight, bloated particles of burnt clay. The LECA has a porous matrix that can immobilize bacteria on the surface and inside the matrix (Su et al. ). The average diameter of LECA for this study was 2–3 cm. Preparation of entrapped bacterial cells For bench-scale experiment with 0.4 or 4% cross-linking agent Strains SU2 and SU3 were individually grown on trypticase soy broth (TSB) at 37 C using a rotary shaker at 150 rpm for 24 h. After a 24-h incubation, bacterial suspensions were added to 0.4 or 4% (w/v) sodium alginate solution in the ratio of 1 : 2 (v/v) with homogenous stirring. Sterilized LECA beads were put into the mixture of bacterial suspension and alginate solution to obtain alginate-coated LECA (AL) beads containing bacterial cells. The AL beads were then poured into 500-mL flasks containing 0.4% (w/v) BaCl2 solution as a cross-linking agent for 2 h. After the formation of an alginate solid film on the surface of LECA beads, the AL beads were then immersed in saturated boric acid solution for 1 h. W
Water Science & Technology
|
69.4
|
2014
Finally, the AL beads were washed with sterile deionized water twice and kept at 4 C before using for further experiments. W
For full-scale experiment Strains SU2 and SU3 were individually grown on TSB and entrapped on the surface of AL beads. The ratio of suspension to alginate solution ¼ 1 : 3 (v/v). Only the ratio of suspension to alginate solution ¼ 1 : 3 (v/v) and the concentration of BaCl2 was 0.4% (w/v).
Time course experiment using bench-scale SBR system experiment The bench-scale SBR was a 20-L acrylic cylinder (65 cm × i.d. 20 cm) with an available volume of 18 L. Two liters of alginate-coated LECA beads were immobilized in the reactor with 18 L anaerobically treated piggery wastewater, achieving a packing ratio of 11%. The ratio of aeration time to non-aeration time was 3.5 h : 2 h, and wastewater samples were taken periodically. The operating mode of the bench-scale IA-SBR (HRT ¼ 3d) was similar to that of Su et al. (b) (Table 1). All wastewater samples were analyzed for COD, biochemical oxygen demand (BOD), suspended solids (SS), and ammonium (NHþ 4 ).
Time course experiment using on-farm full-scale SBR system The full-scale SBR, which was built and normally operated for more than 5 years on a 900-head commercial pig farm in northern Taiwan, was a concrete 95-m3 wastewater treatment basin (4 m × 4.87 m × 4.87 m, H × W × L) with an available volume of 83 m3. The alginate-coated LECA beads (83 L) were equally divided and put into 28 sealed black nylon bags (50 cm × 100 cm), and then immobilized in the SBR with 83 m3 anaerobically treated piggery wastewater achieving a packing ratio of 0.1% (Figure 1). The ratio of aeration time to non-aeration time was 3.5 h : 2 h, and wastewater samples were taken and analyzed periodically (Table 1). All wastewater samples were analyzed for COD, BOD, SS, and NHþ Operating 4. parameters and mode of the full-scale SBR are shown in Table 1.
842
J.-J. Su et al.
Table 1
|
|
Ammonium reduction by full-scale SBR with intermittent aeration
Water Science & Technology
|
69.4
|
2014
Operating parameters and mode of the full-scale SBR
Parameters
Total volume (m3)
95
Operating volume (m3)
83 3
Daily wastewater volume (m /d)
27.7
F/M (kg-BOD/kg-MLSS/d)
0.027
Hydraulic retention time (d)
3
Average MLSS (mg/L)
2,019 ± 945
Sludge age (d)
2
BOD volumetric loading (kg-BOD/m3/d)
0.054
Mode Sequence
Description
Time (h/cycle)
Cycles
Sub-total (h)
Fill
Raw wastewater input.
0.5
1
0.5
React
a
Aeration on with maximum operating volume.
3.5
4
14
Settlea
Aeration off.
2.0
4
8
Idle
Withdrawing excessive sludge from the SBR.
0.5
1
0.5
Draw
Discharging effluent from the SBR.
1.0
1
1
Total
24
a
React and Settle mode were alternately operated four times per day. F/M: food to microorganism ratio; MLSS: mixed liquor suspended solids.
Figure 1
|
Sketch of the full-scale SBR system with alginate-coated LECA beads attached for treating piggery wastewater.
Analysis of wastewater samples Wastewater samples were filtered and the filtrates were analyzed for NHþ 4 , NO2 , and NO3 by ion chromatography
(IC) (Metrohn ion analysis; Metrohn Ltd, Switzerland) (Su et al. ). Wastewater samples were analyzed for COD, BOD, SS concentrations using Standard Methods (APHA ).
843
J.-J. Su et al.
|
Ammonium reduction by full-scale SBR with intermittent aeration
Statistical analysis The experimental data of different samples were then analyzed using the analysis of variance (ANOVA) procedure of data analyzing and graphing software, Origin (OriginLab, Northampton, MA).
RESULTS AND DISCUSSION Time course experiment using bench-scale SBR system experiment The first time course experiment using bench-scale SBR was performed for 240 h under room temperature conditions with intermittent aeration. The initial concentrations of COD, BOD, SS, and NHþ 4 were 506, 73, 450, and 659 mg/L, respectively. The AL beads were cross-linked with 0.4% BaCl2 solution. After 240 h, concentrations of COD, BOD, SS, and NHþ 4 were 245, 16, 54, and 243 mg/L, respectively. It revealed that removal efficiency of COD, BOD, SS, and NHþ 4 after 240 h was 52, 79, 88, and 63%, respectively. The second time course experiment using bench-scale SBR was performed for 192 h under room temperature conditions with intermittent aeration by the mode of Table 1. The initial concentrations of COD, BOD, SS, and NHþ 4
Table 2a
|
Water Science & Technology
|
69.4
|
2014
were 547.5, 107.6, 570.0, and 478.3 mg/L, respectively. The AL beads were cross-linked with 4% BaCl2 solution. Experimental results showed that the removal efficiency of COD, BOD, SS, and NHþ 4 after 192 h was 42.2, 96.4, 61.2, and 34.9%, respectively. Lower alginate concentration for cell entrapment achieved higher oxygen uptake rate by yeast cells using an oxygraph apparatus (oxygen electrode) (Dias et al. ). Experimental results showed that the removal efficiency of bench-scale SBR with AL beads using 0.4% BaCl2 solution as a cross-linking agent was higher than that using 4% BaCl2 solution. Increased SS in the second time course experiment might result from more dissociation of alginate debris from AL beads with higher (4%) alginate content after 48 h. It was difficult to keep initial NHþ 4 concentrations consistent for every experiment, because anaerobically treated piggery wastewater was used as the feedstock of the SBR system. Time course experiment using full-scale SBR system The concentrations of COD, BOD, SS, and NHþ 4 in anaerobically treated piggery wastewater without AL beads were 803 ± 211, 115 ± 58, 379 ± 181, and 478.3 mg/L, respectively (Table 2a). The concentrations of COD, BOD, SS, and NHþ 4 in effluent were 411 ± 78, 77 ± 47, 110 ± 42, and 588 ± 172 mg/L, respectively. Thus, the average removal efficiency of COD, BOD, SS, and ammonium was 47, 33,
Removal of COD, BOD, SS, and NHþ 4 by the full-scale intermittent aeration or continuous aeration SBR COD mg/L
Wastewater samples
NH4þ
SS
Traditional intermittent aeration SBR (n ¼ 11)
Anaerobically treated
803 ± 211
Effluent Removal (%)
BOD
W
Average temperature ( C)
115 ± 58
379 ± 181
895 ± 185
411 ± 78
77 ± 47
110 ± 42
588 ± 172
47 ± 14
33 ± 33
66 ± 19
32 ± 12
602 ± 241
887 ± 132
25 ± 4
Intermittent aeration SBR with alginate-LECA beads (n ¼ 20) Anaerobically treated
990 ± 331
Effluent
377 ± 79
86 ± 50
95 ± 30
484 ± 138
59 ± 11
29 ± 41
83 ± 6
46 ± 12
Removal (%)
142 ± 105
29 ± 3
Continuous aeration SBR with alginate-LECA beads (n ¼ 12) Anaerobically treated Effluent Removal (%) P n: number of samples. Data presented as means ± S.D. NS: not significant (P > 0.05).
1,896 ± 1,105
227 ± 130
1,408 ± 1,155
545 ± 79
131 ± 36
138 ± 37
901 ± 148
65 ± 14
30 ± 32
86 ± 6
30 ± 12
< 0.05
NS
< 0.05
1,292 ± 101
0.05) (Table 2a). Similarly, removal efficiency of SS by the IA-SBR with AL beads was significantly different from that by T-SBR (P < 0.05), but not significantly different from that by the CA-SBR with AL W
Table 2b
|
Water Science & Technology
|
69.4
|
2014
beads (P > 0.05) (Table 2a). However, removal efficiency of NHþ 4 by the IA-SBR with AL beads was significantly different from that by both T-SBR and CA-SBR with AL beads (P < 0.05) (Table 2a). The range of average atmospheric temperature during the farm-scale experimental period was between 20 and 30 C. The experimental results showed that there was no significant difference for BOD removal between CA-SBR and IA-SBR. However, higher temperature only seems to promote ammonium removal by the IA-SBR. Thus, the CA-SBR (SRT ¼ 24 d) cannot promote the removal efficiency of NHþ 4 compared with the IA-SBR on the farm. However, the NHþ 4 removal efficiency of this study (45.6%) by the IA-SBR with NHþ 4 -reducing bacteria was higher than that (36.3%) of Su et al. (b) using suspended activated sludge. For estimating nitrogen balance, there was þ5, 18, and 10% difference by the T-SBR, IA-SBR with AL beads, and CA-SBR with AL beads, respectively. This implied that 36, 27, and 19% of NHþ 4 was oxidized to NO2 , respectively (Table 2b). The remaining NHþ 4 could be assimilated by bac terial cells (NHþ 4 ! NO2 ! NO3 ! biomass) or reduced to þ N2 by denitrification (NH4 ! NO 2 ! NO3 ! NO2 ! N2). The strain SU3 is a heterotrophic nitrifying bacterial strain, which can promote NHþ 4 to be oxidized to NO2 W
Nitrogen balance of time course experiments by the full-scale intermittent aeration or continuous aeration SBR NHþ 4
NO 2
NO 3
mg/L Wastewater samples
Traditional intermittent aeration SBR (n ¼ 11)
Anaerobically treated
895 ± 185
ND
17 ± 2
Effluent
588 ± 172
318 ± 133
29 ± 29
Initial nitrogen (mg/L)
895
Final nitrogen (mg/L)
935
Difference (%)
þ5
Intermittent aeration SBR with alginate-coated LECA beads (n ¼ 20) Anaerobically treated
887 ± 132
ND
12 ± 3
Effluent
484 ± 138
241 ± 138
5±1
887
Final nitrogen (mg/L)
730
ND
27 ± 3
239 ± 253
21 ± 7
Final nitrogen (mg/L)
1,161
Initial nitrogen (mg/L) Difference (%)
18
Continuous aeration SBR with alginate-coated LECA beads (n ¼ 12) Anaerobically treated Effluent Initial nitrogen (mg/L) Difference (%) n: number of samples. Data presented as means ± S.D. ND: not detectable.
1,292 ± 101 901 ± 148 1,292 10
845
Table 3
J.-J. Su et al.
|
|
Ammonium reduction by full-scale SBR with intermittent aeration
Water Science & Technology
|
69.4
|
2014
Establishment cost for using immobilized cell reactor to remove ammonium from piggery wastewater with intermittent aeration
Items
Unit price (US$/unit)
Unit
Quantity
Total amount (US$)
Light-expanded clay aggregates (LECAs)
10
pack
14
140
Black nylon bag
4.3
bags
28
120.4
Fixing rack for hanging black nylon bags
245.7
set
1
245.7
Chemicals for cell immobilization
882
set
1
882
Items
Unit price (US$/kWh)
Consumption (kWh/d)
Days
Total amount (US$)
Electricity expense
0.1
35
365
1,277.5
Sum
1,388.1
Total amount
2,665.6
and then reduced to N2; the strain SU2 is an aerobic denitri fying bacterial strain, which can promote NO 2 and NO3 to be reduced to N2. Experimental data showed that the IASBR with AL beads containing strains SU2 and SU3 significantly reduced NHþ 4 from piggery wastewater. In addition, all experiments were performed outdoors from May to September (average temperature ¼ 20 ± 3–29 ± 3 C). Thus, atmospheric temperature cannot be totally controlled as it can be in the laboratory. The effect of BaCl2 as a cross-linking agent on the Naalginate-based Diclofenac sodium beads was studied by Morshed et al. (). In vitro dissolution data showed that drug release increased with decreased BaCl2 concentration. The high amount of BaCl2 ensures the maximum cross-linking sodium alginate with BaCl2 which augment the conversion of Na-alginate to Ba-alginate. Thus, 0.4% BaCl2 solution was used to prepare AL beads for a time course experiment of the full-scale SBR. High phosphate concentration in piggery wastewater can cause easy breakage of the alginate layer by chelating Ba2þ from the Ba-alginate matrix. Low BaCl2 concentration might result in the formation of a fragile alginate layer and then promoting bio-film formation of NHþ 4 -reducing bacteria on the surface of LECA beads. W
Costs for treating piggery wastewater with immobilized cells in a full-scale SBR system Construction cost for using immobilized strains SU2 and SU3 on AL beads was roughly estimated at US$1,388.1 (Table 3). There were 10 packs of LECA beads and 28 black nylon bags required for making 28 sealed bags of immobilized bacterial strains SU2 and SU3 on alginateLECA beads. Annual operating cost was about US$1,277.5
(US$0.1/kWh × 35 kWh/d × 365 d) and estimated only based on electricity expenses. The annual volume of treated piggery wastewater was 9,855 m3 (27 m3/d × 365 d). Thus, total costs for constructing immobilized bacterial cells on AL beads in a full-scale SBR system was US$2,665.6 for treating 9,855 m3 of piggery wastewater daily. Thus, unit cost was about US$0.27/m3-piggery wastewater.
CONCLUSION The removal efficiency of NHþ 4 by the IA-SBR with AL beads was 46%, which was higher than that (32%) by the T-SBR under mesophilic conditions. However, removal efficiency of NHþ 4 achieved 63% when the packing ratio of AL beads was 11% by a bench-scale IA-SBR in the laboratory. Considering the limited space in the laboratory and the situation on the farm, the packing ratio of the AL beads (specific surface area ¼ 300–451 m2/m3) was set at 0.1% (v/v) for full-scale SBR system. The CA-SBR had better removal efficiency of COD and SS than that by the TSBR (P < 0.05), but they had a close removal efficiency of BOD and NHþ 4 (i.e. T-SBR). The IA-SBR with AL beads had a close removal efficiency of COD, BOD, SS with the CA-SBR, but it had better NHþ 4 removal efficiency than that by the CA-SBR (P < 0.05). Experimental results showed that the IA-SBR with AL beads had more benefits than the CA-SBR. Thus, the IA-SBR with AL beads containing NHþ 4 -reducing bacteria can be a cost-effective option to remove NH4þ from piggery wastewater and reduce eutrophication of surface waters. This operation approach can be extended to pig farmers for intensive NHþ 4 removal on the farm using a full-scale intermittent aeration SBR system.
846
J.-J. Su et al.
|
Ammonium reduction by full-scale SBR with intermittent aeration
ACKNOWLEDGMENTS The study was made possible by grants awarded from the Council of Agriculture (COA). The authors thank Liga Mariya for proof reading.
REFERENCES APHA Standard Methods for the Examination of Water and Wastewater, 20th edn. American Public Health Association/ American Water Works Association/Water Environment Federation, Washington, DC, USA. Dias, J. C. T., Rezende, R. P. & Linardi, V. R. Effects of immobilization in Ba-alginate on nitrile-dependent oxygen uptake rates of Candida guilliermondii. Brazilian J. Microbiol. 32, 221–224. Lin, Y.-H., Hwang, S.-C. J., Wu, J.-Y., Chang, F.-Y. & Chen, K.-C. Simultaneous removal of carbon and nitrogen from swine wastewater using an immobilized-cell reactor. J. Environ. Eng. 132, 423–429. Morshed, M. M., Mallick, J., Nath, A. K., Uddin, M. Z., Dutta, M., Hossain, M. A. & Kawsar, M. H. Effect of barium chloride as a cross linking agent on the sodium alginate based diclofenac sodium beads. Bangladesh Pharm. J. 15, 53–57. Nussinovitch, A. Chapter 2. Bead formation, strengthening, and modification. In: Polymer Macro- and Micro-Gel Beads: Fundamentals and Applications, A. Nussinovitch (ed.). Springer Science þ Business Media, LLC. Reis, C. P., Neufeld, R. J., Vilela, S., Rbeiro, A. J. & Veiga, F. Review and current status of emulsion technology using an internal gelation process for the design of alginate particles. J. Microencapsul. 23, 245–257. Su, J. J., Liu, Y. L., Shu, F. J. & Wu, J. F. a Treatment of piggery wastewater treatment by contact aeration treatment in coordination with the anaerobic fermentation of three-step
Water Science & Technology
|
69.4
|
2014
piggery wastewater treatment (TPWT) process in Taiwan. J. Environ. Sci. Heal. A 32, 55–73. Su, J. J., Kung, C. M., Lin, J., Lian, W. C. & Wu, J. F. b Utilization of sequencing batch reactor for in situ piggery wastewater treatment. J. Environ. Sci. Heal. A 32, 391–405. Su, J. J., Lian, W. C. & Wu, J. F. Studies on piggery wastewater treatment by a full-scale sequencing batch reactor after anaerobic fermentation. J. Agri. Assoc. China 188, 47–59 (in English). Su, J. J., Liu, B. Y., Lin, J. & Yang, J. B. a Isolation of an anaerobic denitrifying bacterial strain NS-2 from the activated sludge of piggery wastewater treatment systems in Taiwan possessing denitrification under 92% atmosphere. J. Appl. Microbiol. 91, 853–860. Su, J. J., Liu, C. Y. & Liu, B. Y. b Comparison of aerobic denitrification under pure oxygen atmosphere by Thiosphaera pantotropha ATCC 35512 and Pseudomonas stutzeri SU2 newly isolated from the activated sludge of a piggery wastewater treatment system. J. Appl. Microbiol. 90 (3), 457–462. Su, J. J., Liu, B. Y. & Chang, Y. C. c Identification of an interfering factor on chemical oxygen demand (COD) determination in piggery wastewater and elimination of the factor by an indigenous Pseudomonas stutzeri strain. Lett. Appl. Microbiol. 33, 440–444. Su, J. J., Yeh, K. S. & Tseng, P. W. A strain of Pseudomonas sp. isolated from piggery wastewater treatment systems with heterotrophic nitrification capability in Taiwan. Curr. Microbiol. 53, 77–81. Su, J. J., Chen, Y. J., Chang, Y. C. & Tang, S. C. Isolation of sulfur oxidizers for desulfurizing biogas produced from anaerobic piggery wastewater treatment in Taiwan. Aust. J. Exp. Agric. 48, 193–197. Su, J. J., Chang, Y. C., Chen, Y. J., Chang, C. K. & Lee, S. Y. Hydrogen sulfide removal from livestock biogas by a farmscale bio-filter desulfurization system. Water Sci. Technol. 67, 1288–1293. Su, J. J., Chen, Y. J. & Chang, Y. C. A study of a pilot-scale biogas bio-filter system for utilization on pig farms. J. Agric. Sci. 152 (2). Published online in January 2013 (doi:10.1017/ S0021859612001086).
First received 7 May 2013; accepted in revised form 2 December 2013. Available online 14 December 2013
Copyright of Water Science & Technology is the property of IWA Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
© IWA Publishing 2014 Water Science & Technology
|
69.4
|
2014
Ammonium reduction from piggery wastewater using immobilized ammonium-reducing bacteria with a full-scale sequencing batch reactor on farm Jung-Jeng Su, Yuan-Chie Chang and Shun-Ming Huang
ABSTRACT This work aims to evaluate the efficiency of ammonium removal from piggery wastewater by an intermittent aeration (IA) sequencing batch reactor (SBR) with immobilized
NHþ 4 -reducing
bacteria
under mesophilic conditions. When a 20-L bench-scale SBR with 11% (v/v) of alginate beads þ containing NHþ 4 -reducing bacteria was used, removal efficiency of NH4 was 63% after 240 h. When a
full-scale SBR system (available volume ¼ 83 m3) with 0.1% (v/v) of alginate-coated light-expanded þ clay aggregates beads containing NHþ 4 -reducing bacteria was used, removal efficiency of NH4 by the
full-scale intermittent aeration SBR (IA-SBR) was significantly different from both traditional intermittent aeration SBR (T-SBR) and the continuous aeration SBR with AL beads containing
Jung-Jeng Su (corresponding author) Yuan-Chie Chang Shun-Ming Huang Department of Animal Science and Technology, National Taiwan University, Taipei, Taiwan and Bioenergy Research Center, National Taiwan University, Taipei, Taiwan E-mail: [email protected]
NHþ 4 -reducing bacteria (P < 0.05). In summary, the IA-SBR with AL beads can significantly promote removal efficiency of NHþ 4 on farm. Key words
| aerobic denitrifier, ammonium removal, heterotrophic nitrifier, piggery wastewater, sequencing batch reactor
INTRODUCTION The conventional method of treating piggery wastewater in Taiwan is the three-step piggery wastewater treatment system, involving solid/liquid separation, anaerobic treatment, and aerobic treatment (Su et al. a). The removal efficiency of total Kjeldahl nitrogen (TKN) ranged from 42.5 to 71.1% year round using a full-scale sequencing batch reactor (SBR) system on a 500-head pig farm (Su et al. ). The higher the atmospheric temperature, the better TKN removal efficiency can be achieved. Lin’s experimental results showed that the removal efficiency of chemical oxygen demand (COD) and total nitrogen (TN) was >70 and 8%, respectively in continuous aeration (CA) mode under a hydraulic retention time (HRT) of 10 days. However, the removal efficiency of COD and TN was 85 and 46%, respectively in intermittent aeration (IA) mode with 50% aeration duration to cycle time under the same HRT (Lin et al. ). Ammonium formed from the anaerobic treatment process can be removed by means of oxidation of ammonium and reduction of nitrate and nitrite using a full-scale SBR
doi: 10.2166/wst.2013.787
system with intermittent aeration (Su et al. b, ). Ammonium and nitrate can be effectively removed by immobilized heterotrophic nitrifying and aerobic denitrifying bacteria with intermittent aeration process. The removal rate of nitrate was 0.032 mmole NO 3 -N/g-cell/h by the aerobic denitrifying bacteria (Pseudomonas alcaligenes strain SU2) under aerobic conditions (Su et al. a, b). Furthermore, the removal rate of ammonium was 1.75 mmol NHþ 4 /g-cell/h by the aerobic denitrifying bacteria (P. stutzeri strain SU3) under limited aerobic conditions (Su et al. ). Alginate is commonly used for entrapment of any types of cell such as bacteria, yeast, fungi, and eukaryotic cells (Nussinovitch ). Alginate gels in the presence of divalent cations [e.g. 2þ Ba þ 2NaþAlg ! Ba2þ(Alg)2 þ 2Naþ] can be heat treated without melting. Gelling depends on ion binding, Ba2þ > Sr2þ > Zn2þ > Ca2þ ≫ Mg2þ, with the control of cation addition (Reis et al. ). The main goal of this study was to evaluate the removal efficiency of carbon and ammonium using alginate-light-expanded clay aggregates
841
J.-J. Su et al.
|
Ammonium reduction by full-scale SBR with intermittent aeration
(LECA) beads coated with co-immobilized bacterial cells in a full-scale SBR system of a commercial pig farm. All removal efficiency of carbon and ammonium as well as the costs of construction and operation were counted for economic analysis.
MATERIALS AND METHODS Microorganisms The NHþ 4 -reducing bacterial strains, P. stutzeri SU2 and P. alcaligenes SU3 were isolated from the piggery sludge of commercial pig farms in Taiwan. Pseudomonas stutzeri SU2 is an aerobic denitrifying bacterial strain and P. alcaligenes SU3 is a heterotrophic nitrifying bacterial strain (Su et al. a, b, c, ). Both strains SU2 and SU3 were used as NHþ 4 -reducing agents for this study. Bio-carrier for microorganisms The bio-carrier was LECAs and previously applied to the biogas bio-desulfurization system (Su et al. , ). LECA consists of small, lightweight, bloated particles of burnt clay. The LECA has a porous matrix that can immobilize bacteria on the surface and inside the matrix (Su et al. ). The average diameter of LECA for this study was 2–3 cm. Preparation of entrapped bacterial cells For bench-scale experiment with 0.4 or 4% cross-linking agent Strains SU2 and SU3 were individually grown on trypticase soy broth (TSB) at 37 C using a rotary shaker at 150 rpm for 24 h. After a 24-h incubation, bacterial suspensions were added to 0.4 or 4% (w/v) sodium alginate solution in the ratio of 1 : 2 (v/v) with homogenous stirring. Sterilized LECA beads were put into the mixture of bacterial suspension and alginate solution to obtain alginate-coated LECA (AL) beads containing bacterial cells. The AL beads were then poured into 500-mL flasks containing 0.4% (w/v) BaCl2 solution as a cross-linking agent for 2 h. After the formation of an alginate solid film on the surface of LECA beads, the AL beads were then immersed in saturated boric acid solution for 1 h. W
Water Science & Technology
|
69.4
|
2014
Finally, the AL beads were washed with sterile deionized water twice and kept at 4 C before using for further experiments. W
For full-scale experiment Strains SU2 and SU3 were individually grown on TSB and entrapped on the surface of AL beads. The ratio of suspension to alginate solution ¼ 1 : 3 (v/v). Only the ratio of suspension to alginate solution ¼ 1 : 3 (v/v) and the concentration of BaCl2 was 0.4% (w/v).
Time course experiment using bench-scale SBR system experiment The bench-scale SBR was a 20-L acrylic cylinder (65 cm × i.d. 20 cm) with an available volume of 18 L. Two liters of alginate-coated LECA beads were immobilized in the reactor with 18 L anaerobically treated piggery wastewater, achieving a packing ratio of 11%. The ratio of aeration time to non-aeration time was 3.5 h : 2 h, and wastewater samples were taken periodically. The operating mode of the bench-scale IA-SBR (HRT ¼ 3d) was similar to that of Su et al. (b) (Table 1). All wastewater samples were analyzed for COD, biochemical oxygen demand (BOD), suspended solids (SS), and ammonium (NHþ 4 ).
Time course experiment using on-farm full-scale SBR system The full-scale SBR, which was built and normally operated for more than 5 years on a 900-head commercial pig farm in northern Taiwan, was a concrete 95-m3 wastewater treatment basin (4 m × 4.87 m × 4.87 m, H × W × L) with an available volume of 83 m3. The alginate-coated LECA beads (83 L) were equally divided and put into 28 sealed black nylon bags (50 cm × 100 cm), and then immobilized in the SBR with 83 m3 anaerobically treated piggery wastewater achieving a packing ratio of 0.1% (Figure 1). The ratio of aeration time to non-aeration time was 3.5 h : 2 h, and wastewater samples were taken and analyzed periodically (Table 1). All wastewater samples were analyzed for COD, BOD, SS, and NHþ Operating 4. parameters and mode of the full-scale SBR are shown in Table 1.
842
J.-J. Su et al.
Table 1
|
|
Ammonium reduction by full-scale SBR with intermittent aeration
Water Science & Technology
|
69.4
|
2014
Operating parameters and mode of the full-scale SBR
Parameters
Total volume (m3)
95
Operating volume (m3)
83 3
Daily wastewater volume (m /d)
27.7
F/M (kg-BOD/kg-MLSS/d)
0.027
Hydraulic retention time (d)
3
Average MLSS (mg/L)
2,019 ± 945
Sludge age (d)
2
BOD volumetric loading (kg-BOD/m3/d)
0.054
Mode Sequence
Description
Time (h/cycle)
Cycles
Sub-total (h)
Fill
Raw wastewater input.
0.5
1
0.5
React
a
Aeration on with maximum operating volume.
3.5
4
14
Settlea
Aeration off.
2.0
4
8
Idle
Withdrawing excessive sludge from the SBR.
0.5
1
0.5
Draw
Discharging effluent from the SBR.
1.0
1
1
Total
24
a
React and Settle mode were alternately operated four times per day. F/M: food to microorganism ratio; MLSS: mixed liquor suspended solids.
Figure 1
|
Sketch of the full-scale SBR system with alginate-coated LECA beads attached for treating piggery wastewater.
Analysis of wastewater samples Wastewater samples were filtered and the filtrates were analyzed for NHþ 4 , NO2 , and NO3 by ion chromatography
(IC) (Metrohn ion analysis; Metrohn Ltd, Switzerland) (Su et al. ). Wastewater samples were analyzed for COD, BOD, SS concentrations using Standard Methods (APHA ).
843
J.-J. Su et al.
|
Ammonium reduction by full-scale SBR with intermittent aeration
Statistical analysis The experimental data of different samples were then analyzed using the analysis of variance (ANOVA) procedure of data analyzing and graphing software, Origin (OriginLab, Northampton, MA).
RESULTS AND DISCUSSION Time course experiment using bench-scale SBR system experiment The first time course experiment using bench-scale SBR was performed for 240 h under room temperature conditions with intermittent aeration. The initial concentrations of COD, BOD, SS, and NHþ 4 were 506, 73, 450, and 659 mg/L, respectively. The AL beads were cross-linked with 0.4% BaCl2 solution. After 240 h, concentrations of COD, BOD, SS, and NHþ 4 were 245, 16, 54, and 243 mg/L, respectively. It revealed that removal efficiency of COD, BOD, SS, and NHþ 4 after 240 h was 52, 79, 88, and 63%, respectively. The second time course experiment using bench-scale SBR was performed for 192 h under room temperature conditions with intermittent aeration by the mode of Table 1. The initial concentrations of COD, BOD, SS, and NHþ 4
Table 2a
|
Water Science & Technology
|
69.4
|
2014
were 547.5, 107.6, 570.0, and 478.3 mg/L, respectively. The AL beads were cross-linked with 4% BaCl2 solution. Experimental results showed that the removal efficiency of COD, BOD, SS, and NHþ 4 after 192 h was 42.2, 96.4, 61.2, and 34.9%, respectively. Lower alginate concentration for cell entrapment achieved higher oxygen uptake rate by yeast cells using an oxygraph apparatus (oxygen electrode) (Dias et al. ). Experimental results showed that the removal efficiency of bench-scale SBR with AL beads using 0.4% BaCl2 solution as a cross-linking agent was higher than that using 4% BaCl2 solution. Increased SS in the second time course experiment might result from more dissociation of alginate debris from AL beads with higher (4%) alginate content after 48 h. It was difficult to keep initial NHþ 4 concentrations consistent for every experiment, because anaerobically treated piggery wastewater was used as the feedstock of the SBR system. Time course experiment using full-scale SBR system The concentrations of COD, BOD, SS, and NHþ 4 in anaerobically treated piggery wastewater without AL beads were 803 ± 211, 115 ± 58, 379 ± 181, and 478.3 mg/L, respectively (Table 2a). The concentrations of COD, BOD, SS, and NHþ 4 in effluent were 411 ± 78, 77 ± 47, 110 ± 42, and 588 ± 172 mg/L, respectively. Thus, the average removal efficiency of COD, BOD, SS, and ammonium was 47, 33,
Removal of COD, BOD, SS, and NHþ 4 by the full-scale intermittent aeration or continuous aeration SBR COD mg/L
Wastewater samples
NH4þ
SS
Traditional intermittent aeration SBR (n ¼ 11)
Anaerobically treated
803 ± 211
Effluent Removal (%)
BOD
W
Average temperature ( C)
115 ± 58
379 ± 181
895 ± 185
411 ± 78
77 ± 47
110 ± 42
588 ± 172
47 ± 14
33 ± 33
66 ± 19
32 ± 12
602 ± 241
887 ± 132
25 ± 4
Intermittent aeration SBR with alginate-LECA beads (n ¼ 20) Anaerobically treated
990 ± 331
Effluent
377 ± 79
86 ± 50
95 ± 30
484 ± 138
59 ± 11
29 ± 41
83 ± 6
46 ± 12
Removal (%)
142 ± 105
29 ± 3
Continuous aeration SBR with alginate-LECA beads (n ¼ 12) Anaerobically treated Effluent Removal (%) P n: number of samples. Data presented as means ± S.D. NS: not significant (P > 0.05).
1,896 ± 1,105
227 ± 130
1,408 ± 1,155
545 ± 79
131 ± 36
138 ± 37
901 ± 148
65 ± 14
30 ± 32
86 ± 6
30 ± 12
< 0.05
NS
< 0.05
1,292 ± 101
0.05) (Table 2a). Similarly, removal efficiency of SS by the IA-SBR with AL beads was significantly different from that by T-SBR (P < 0.05), but not significantly different from that by the CA-SBR with AL W
Table 2b
|
Water Science & Technology
|
69.4
|
2014
beads (P > 0.05) (Table 2a). However, removal efficiency of NHþ 4 by the IA-SBR with AL beads was significantly different from that by both T-SBR and CA-SBR with AL beads (P < 0.05) (Table 2a). The range of average atmospheric temperature during the farm-scale experimental period was between 20 and 30 C. The experimental results showed that there was no significant difference for BOD removal between CA-SBR and IA-SBR. However, higher temperature only seems to promote ammonium removal by the IA-SBR. Thus, the CA-SBR (SRT ¼ 24 d) cannot promote the removal efficiency of NHþ 4 compared with the IA-SBR on the farm. However, the NHþ 4 removal efficiency of this study (45.6%) by the IA-SBR with NHþ 4 -reducing bacteria was higher than that (36.3%) of Su et al. (b) using suspended activated sludge. For estimating nitrogen balance, there was þ5, 18, and 10% difference by the T-SBR, IA-SBR with AL beads, and CA-SBR with AL beads, respectively. This implied that 36, 27, and 19% of NHþ 4 was oxidized to NO2 , respectively (Table 2b). The remaining NHþ 4 could be assimilated by bac terial cells (NHþ 4 ! NO2 ! NO3 ! biomass) or reduced to þ N2 by denitrification (NH4 ! NO 2 ! NO3 ! NO2 ! N2). The strain SU3 is a heterotrophic nitrifying bacterial strain, which can promote NHþ 4 to be oxidized to NO2 W
Nitrogen balance of time course experiments by the full-scale intermittent aeration or continuous aeration SBR NHþ 4
NO 2
NO 3
mg/L Wastewater samples
Traditional intermittent aeration SBR (n ¼ 11)
Anaerobically treated
895 ± 185
ND
17 ± 2
Effluent
588 ± 172
318 ± 133
29 ± 29
Initial nitrogen (mg/L)
895
Final nitrogen (mg/L)
935
Difference (%)
þ5
Intermittent aeration SBR with alginate-coated LECA beads (n ¼ 20) Anaerobically treated
887 ± 132
ND
12 ± 3
Effluent
484 ± 138
241 ± 138
5±1
887
Final nitrogen (mg/L)
730
ND
27 ± 3
239 ± 253
21 ± 7
Final nitrogen (mg/L)
1,161
Initial nitrogen (mg/L) Difference (%)
18
Continuous aeration SBR with alginate-coated LECA beads (n ¼ 12) Anaerobically treated Effluent Initial nitrogen (mg/L) Difference (%) n: number of samples. Data presented as means ± S.D. ND: not detectable.
1,292 ± 101 901 ± 148 1,292 10
845
Table 3
J.-J. Su et al.
|
|
Ammonium reduction by full-scale SBR with intermittent aeration
Water Science & Technology
|
69.4
|
2014
Establishment cost for using immobilized cell reactor to remove ammonium from piggery wastewater with intermittent aeration
Items
Unit price (US$/unit)
Unit
Quantity
Total amount (US$)
Light-expanded clay aggregates (LECAs)
10
pack
14
140
Black nylon bag
4.3
bags
28
120.4
Fixing rack for hanging black nylon bags
245.7
set
1
245.7
Chemicals for cell immobilization
882
set
1
882
Items
Unit price (US$/kWh)
Consumption (kWh/d)
Days
Total amount (US$)
Electricity expense
0.1
35
365
1,277.5
Sum
1,388.1
Total amount
2,665.6
and then reduced to N2; the strain SU2 is an aerobic denitri fying bacterial strain, which can promote NO 2 and NO3 to be reduced to N2. Experimental data showed that the IASBR with AL beads containing strains SU2 and SU3 significantly reduced NHþ 4 from piggery wastewater. In addition, all experiments were performed outdoors from May to September (average temperature ¼ 20 ± 3–29 ± 3 C). Thus, atmospheric temperature cannot be totally controlled as it can be in the laboratory. The effect of BaCl2 as a cross-linking agent on the Naalginate-based Diclofenac sodium beads was studied by Morshed et al. (). In vitro dissolution data showed that drug release increased with decreased BaCl2 concentration. The high amount of BaCl2 ensures the maximum cross-linking sodium alginate with BaCl2 which augment the conversion of Na-alginate to Ba-alginate. Thus, 0.4% BaCl2 solution was used to prepare AL beads for a time course experiment of the full-scale SBR. High phosphate concentration in piggery wastewater can cause easy breakage of the alginate layer by chelating Ba2þ from the Ba-alginate matrix. Low BaCl2 concentration might result in the formation of a fragile alginate layer and then promoting bio-film formation of NHþ 4 -reducing bacteria on the surface of LECA beads. W
Costs for treating piggery wastewater with immobilized cells in a full-scale SBR system Construction cost for using immobilized strains SU2 and SU3 on AL beads was roughly estimated at US$1,388.1 (Table 3). There were 10 packs of LECA beads and 28 black nylon bags required for making 28 sealed bags of immobilized bacterial strains SU2 and SU3 on alginateLECA beads. Annual operating cost was about US$1,277.5
(US$0.1/kWh × 35 kWh/d × 365 d) and estimated only based on electricity expenses. The annual volume of treated piggery wastewater was 9,855 m3 (27 m3/d × 365 d). Thus, total costs for constructing immobilized bacterial cells on AL beads in a full-scale SBR system was US$2,665.6 for treating 9,855 m3 of piggery wastewater daily. Thus, unit cost was about US$0.27/m3-piggery wastewater.
CONCLUSION The removal efficiency of NHþ 4 by the IA-SBR with AL beads was 46%, which was higher than that (32%) by the T-SBR under mesophilic conditions. However, removal efficiency of NHþ 4 achieved 63% when the packing ratio of AL beads was 11% by a bench-scale IA-SBR in the laboratory. Considering the limited space in the laboratory and the situation on the farm, the packing ratio of the AL beads (specific surface area ¼ 300–451 m2/m3) was set at 0.1% (v/v) for full-scale SBR system. The CA-SBR had better removal efficiency of COD and SS than that by the TSBR (P < 0.05), but they had a close removal efficiency of BOD and NHþ 4 (i.e. T-SBR). The IA-SBR with AL beads had a close removal efficiency of COD, BOD, SS with the CA-SBR, but it had better NHþ 4 removal efficiency than that by the CA-SBR (P < 0.05). Experimental results showed that the IA-SBR with AL beads had more benefits than the CA-SBR. Thus, the IA-SBR with AL beads containing NHþ 4 -reducing bacteria can be a cost-effective option to remove NH4þ from piggery wastewater and reduce eutrophication of surface waters. This operation approach can be extended to pig farmers for intensive NHþ 4 removal on the farm using a full-scale intermittent aeration SBR system.
846
J.-J. Su et al.
|
Ammonium reduction by full-scale SBR with intermittent aeration
ACKNOWLEDGMENTS The study was made possible by grants awarded from the Council of Agriculture (COA). The authors thank Liga Mariya for proof reading.
REFERENCES APHA Standard Methods for the Examination of Water and Wastewater, 20th edn. American Public Health Association/ American Water Works Association/Water Environment Federation, Washington, DC, USA. Dias, J. C. T., Rezende, R. P. & Linardi, V. R. Effects of immobilization in Ba-alginate on nitrile-dependent oxygen uptake rates of Candida guilliermondii. Brazilian J. Microbiol. 32, 221–224. Lin, Y.-H., Hwang, S.-C. J., Wu, J.-Y., Chang, F.-Y. & Chen, K.-C. Simultaneous removal of carbon and nitrogen from swine wastewater using an immobilized-cell reactor. J. Environ. Eng. 132, 423–429. Morshed, M. M., Mallick, J., Nath, A. K., Uddin, M. Z., Dutta, M., Hossain, M. A. & Kawsar, M. H. Effect of barium chloride as a cross linking agent on the sodium alginate based diclofenac sodium beads. Bangladesh Pharm. J. 15, 53–57. Nussinovitch, A. Chapter 2. Bead formation, strengthening, and modification. In: Polymer Macro- and Micro-Gel Beads: Fundamentals and Applications, A. Nussinovitch (ed.). Springer Science þ Business Media, LLC. Reis, C. P., Neufeld, R. J., Vilela, S., Rbeiro, A. J. & Veiga, F. Review and current status of emulsion technology using an internal gelation process for the design of alginate particles. J. Microencapsul. 23, 245–257. Su, J. J., Liu, Y. L., Shu, F. J. & Wu, J. F. a Treatment of piggery wastewater treatment by contact aeration treatment in coordination with the anaerobic fermentation of three-step
Water Science & Technology
|
69.4
|
2014
piggery wastewater treatment (TPWT) process in Taiwan. J. Environ. Sci. Heal. A 32, 55–73. Su, J. J., Kung, C. M., Lin, J., Lian, W. C. & Wu, J. F. b Utilization of sequencing batch reactor for in situ piggery wastewater treatment. J. Environ. Sci. Heal. A 32, 391–405. Su, J. J., Lian, W. C. & Wu, J. F. Studies on piggery wastewater treatment by a full-scale sequencing batch reactor after anaerobic fermentation. J. Agri. Assoc. China 188, 47–59 (in English). Su, J. J., Liu, B. Y., Lin, J. & Yang, J. B. a Isolation of an anaerobic denitrifying bacterial strain NS-2 from the activated sludge of piggery wastewater treatment systems in Taiwan possessing denitrification under 92% atmosphere. J. Appl. Microbiol. 91, 853–860. Su, J. J., Liu, C. Y. & Liu, B. Y. b Comparison of aerobic denitrification under pure oxygen atmosphere by Thiosphaera pantotropha ATCC 35512 and Pseudomonas stutzeri SU2 newly isolated from the activated sludge of a piggery wastewater treatment system. J. Appl. Microbiol. 90 (3), 457–462. Su, J. J., Liu, B. Y. & Chang, Y. C. c Identification of an interfering factor on chemical oxygen demand (COD) determination in piggery wastewater and elimination of the factor by an indigenous Pseudomonas stutzeri strain. Lett. Appl. Microbiol. 33, 440–444. Su, J. J., Yeh, K. S. & Tseng, P. W. A strain of Pseudomonas sp. isolated from piggery wastewater treatment systems with heterotrophic nitrification capability in Taiwan. Curr. Microbiol. 53, 77–81. Su, J. J., Chen, Y. J., Chang, Y. C. & Tang, S. C. Isolation of sulfur oxidizers for desulfurizing biogas produced from anaerobic piggery wastewater treatment in Taiwan. Aust. J. Exp. Agric. 48, 193–197. Su, J. J., Chang, Y. C., Chen, Y. J., Chang, C. K. & Lee, S. Y. Hydrogen sulfide removal from livestock biogas by a farmscale bio-filter desulfurization system. Water Sci. Technol. 67, 1288–1293. Su, J. J., Chen, Y. J. & Chang, Y. C. A study of a pilot-scale biogas bio-filter system for utilization on pig farms. J. Agric. Sci. 152 (2). Published online in January 2013 (doi:10.1017/ S0021859612001086).
First received 7 May 2013; accepted in revised form 2 December 2013. Available online 14 December 2013
Copyright of Water Science & Technology is the property of IWA Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
