VIETNAM NATIONAL UNIVERSITY, HANOI VIETNAM JAPAN UNIVERSITY VU THI THOM STUDY ON POTENTIAL PLANTS FOR USE IN CONSTRUCTED WETLAND TO STRENGTHEN PHOSPHORUS TREATMENT PERFORMANCE FROM SWINE WASTEWATER MA[.]
VIETNAM NATIONAL UNIVERSITY, HANOI VIETNAM JAPAN UNIVERSITY VU THI THOM STUDY ON POTENTIAL PLANTS FOR USE IN CONSTRUCTED WETLAND TO STRENGTHEN PHOSPHORUS TREATMENT PERFORMANCE FROM SWINE WASTEWATER MASTER'S THESIS Hanoi, 2019 VIETNAM NATIONAL UNIVERSITY, HANOI VIETNAM JAPAN UNIVERSITY VU THI THOM STUDY ON POTENTIAL PLANTS FOR USE IN CONSTRUCTED WETLAND TO STRENGTHEN PHOSPHORUS TREATMENT PERFORMANCE FROM SWINE WASTEWATER MAJOR: ENVIRONMENTAL ENGINEERING CODE: PILOT SUPERVISORS DR NGUYEN THI AN HANG ASSOC PROF DR SATO KEISUKE DR NGUYEN THI HOANG HA Hanoi, 2019 ACKNOWLEDGMENTS First of all, I would like to express the sincere gratitude to my principal supervisor, Dr Nguyen Thi An Hang at VNU Vietnam Japan University, for accepting me as her master student and continuous teaching and supporting me in the process of doing experiments as well as writing essays and making presentations She always encourages and is willing to help me when I have difficulties She is always beside me to teach me how to work effectively This helps me grow up in both personal and professional aspects A special thanks also go to Assoc Prof Dr Sato Keisuke for his recommendations to my research He provided me with the best conditions for implementing my experiments during my internship in Japan He is wholeheartedly devoted to his students I would like to express my deepest thanks to Dr Nguyen Thi Hoang Ha She gave me valuable supports in developing research methods, and enthusiastically guided me to fullfil my thesis I always feel grateful to her for accompanying me for such a long time The second, I would like to send my sciencere thanks to Prof Dr Jun Nakajima for supporting not only me but also all of memerbers in my class during Master course He cares for us like his children And he is our respected father The third, I am grateful to Ms Nguyen Thi Xuyen, the project staff, for always supporting me in conducting experiments as well as analyzing environmental parameters This research is funded by Vietnam National Foundation for Science and Technology Development (NAFOSTED) under grant number 105.99-2018.13, 2018 Asean Research Center (ARC) research grant of Vietnam National University, Hanoi (VNU), and Japan International Cooperation Agency (JICA) research grant for the academic year of 2018-2019 My heartfelt thanks and gratitudes to my family for their unconditional helps with plant sampling, the love and encouragement Hanoi, June 9th, 2019 Vu Thi Thom i TABLE OF CONTENTS ACKNOWLEDGMENTS i LIST OF TABLES ii LIST OF FIGURES iii LIST OF ABBREVIATIONS v INTRODUCTION vi CHAPTER 1: LITERATURE REVIEW 1.1 Overview of the situation of pig husbandry in Vietnam .1 1.1.1 Current status and development orientation of pig breeding 1.1.2 Environmental pollution due to swine wastewater 1.1.3 Technologies for the treatment of swine wastewater .4 1.2 Phosphorous pollution and treatment technologies .5 1.2.1 Phosphorus pollution and its consequences 1.2.2 Phosphorus treatment technologies 1.3 Constructed wetland for wastewater treatment 1.3.1 Definition and classification of CWs 1.3.2 Influential factors and treatment performance 1.4 Removal phosphorus by plants in the CWs 12 1.4.1 Classification of plants used in CWs 12 1.4.2 Removal P mechanisms by plants 14 CHAPTER 2: MATERIALS AND RESEARCH METHODOLOGY .18 2.1 Research object, scale, and scope 18 2.1.1 Research object .18 2.1.2 Research scale & scope .18 2.2 Materials, chemicals and equipment 19 2.2.1 Materials 19 2.2.2 Experimental design 20 2.2.3 Plant sample preparation and P analysis .25 2.2.4 Analysis of other water quality parameters 26 2.3 Data calculation .27 2.4 Data statistical analysis .28 CHAPTER 3: RESULTS AND DISCUSSION .29 3.1 Screening potential plants for use in the CWs 29 3.1.1 Selection of potential plants based on their P content and biomass growth .29 3.1.2 Selection of CWs plants based on other growth characteristics 33 3.2 Factors influencing the growth and uptake of p of Cymbopogon citratus and Ubon paspalum 35 3.2.1 Effect of initial P concentration 35 3.2.2 Effect of pH 42 3.2.3 Effect of plant age 45 3.2.4 Effect of plant density 49 3.2.5 Effect of water level 52 3.3 Applicability of the selected plants in the constructed wetland 54 CHAPTER 4: CONCLUSION AND RECOMMENDATION 57 4.1 Conclusion 57 4.2 Recommendations 57 REFERENCE 58 APPENDIX 62 LIST OF TABLES Table 1.1 Annual growth rate of culture sector (%) Table 1.2 Composition and characteristics of swine wastewater Table 1.3 Methods for handing and using liquids at systems Table 1.4 main parameters of swine wastewater after biogas treatment Table 1.5 P removal by Constructed Wetland 11 Table 1.6 Plant species are used to treat swine wastewater .13 Table 1.7 P removal efficiency by plants in CW (Jesus et al., 2017) .15 Table 2.1 The list of investigated plants 19 Table 2.2 Methods for examination of water quality parameters 27 Table 3.1 The P content in plants use for phytoremediation or CWs 31 Table 3.2 The P removal potential of the studied plants 33 Table 3.3 Growth characteristics of potential plants 34 Table 3.4 The P removal efficiency by different plant species 39 Table 3.5 Biomass growth rate of Ubon paspalum at different plant ages 48 Table 3.6 Effect plant density on the biomass growth rate of Ubon paspalum .51 ii LIST OF FIGURES Figure 1.1 Eutrophication: cause and effect .5 Figure 1.2 P removal in CWs Figure 2.1 Scheme of horizontal constructed wetland 23 (at the start of experiment) 23 Figure 2.2 The structure of filter media in CWs and adsorption units 24 Figure 2.3 Plant sample preparation and analysis 25 Figure 2.4 Images of apparatus used in this study 26 Figure 3.1 The P content and its distribution in the studied plants 29 Figure 3.2 Images of the investigated plants in this study 34 Figure 3.3 Effect of initial P concentration on the removal efficiency of Cymbopogon citratus 37 Figure 3.4 Effect of initial P concentration on the removal efficiency of Ubon paspalum 37 Figure 3.5 P concentration left in solution plant with Ubon paspalum 38 Figure 3.6 P concentration left in solution planted with Cymbopogon citratus 38 Figure 3.7 Effect of intial P concentration on P removal rate of Ubon paspalum 40 Figure 3.8 Effect of intial P concentration on P removal rate of Cymbopogon citratus 40 Figure 3.9 Ubon paspalum died at the highest P concentration 41 Figure 3.10 Cymbopogon citratus could adapt with a wide range of initial P concentration 41 Figure 3.11 Normal growth of Cymbopogon citratus at all pH values 42 Figure 3.12 The death of Ubon paspalum at pH values of 9&11 43 Figure 3.13 Speciation of P in solution at various pH conditions 43 Figure 3.14 Effect of pH on P removal efficiency of Ubon paspalum and Cymbopogon citratus 44 Figure 3.15 Effect of pH on P removal rate of Ubon paspalum and Cymbopogon citratus 45 iii Figure 3.16 Effect of plant age on P removal efficiency and P removal rate of Ubon paspalum (hydroponic experiment) 47 Figure 3.17 The effect of plant age on the growth of root system 47 Figure 3.18 Effect of plant age on the biomass growth of Ubon paspalum 48 (experiment with garden soil) 48 Figure 3.19 Effect of plant density on P removal rate of the investigated plants 50 Figure 3.20 Effect of plant density on the P removal efficiency of the investigated plants 50 Figure 3.21 The root growth of Ubon paspalum at different plant densities 52 Figure 3.22 Effect of Ph on P removal rate of plants 53 Figure 3.23 Effect of water level on root growth of Ubon paspalum 54 Figure 3.24 The change of phosphorus in the effluent over the time 54 Figure 3.25 P removal efficiency and Ph after treatment of HFCWs 55 Figure 3.26 The plants growth well after weeks of system operation 56 iv LIST OF ABBREVIATIONS COD Chemical oxygen demand CW BOD EBPR EPA HF HLR HRT SSF SF TN TP TSS VF WHC Constructed Wetland Biological oxygen demand Enhanced biological phosphorus removal Environmental Protection Agency Horizontal flow Hydraulic loading rate Hydraulic retention time Subsurface water flow Surface flow Total nitrogen Total phosphorus Total suspended solids Vertical flow White hard clam v INTRODUCTION Background In Vietnam, in recent years, pig breeding industry has developed rapidly Since most of pig farms have not designed and operated appropriately, wastewater from pig farms cause serious environmental pollution, which poses a high risk to public health and surrounding ecosystems Therefore, the proper treatment of swine wastewater is urgent and necessary At present, swine wastewater in Vietnam is normally treated by biogas technology However, the concentration of pollutants in the effluent is still high, exceeding national discharge standards (QCVN 01-79: 2011/BNNPTNT) Thus, further processing after biogas treatment of swine wastewater is mandatory Constructed wetlands (CWs) is a promising technology, which possesses many advantages, such as cost-effective, green technology (Wu et al., 2015; Yang et al, 2018;), low land, energy, and less-operational requirements (Wu et al., 2015); simple construction and operation (Bunce et al., 2018) However, the wide application of CWs is limited by intensive land requirement, long-term unsustainability (Bunce et al., 2018) Especially, although CWs can achieve high removal efficiency with TSS, COD, BOD, it is demonstrated to be inefficient in nutrient elimination It is wellknown that the treatment performance of phosphorus by CWs is low and unstable Hence, the enhancement of phosphorus removal by CW is of great significance Since phosphorus is eliminated by CWs mainly via substrate adsorption, plant uptake, microbial degradation, selection and application of potential plants in CWs plays an important role Plant-based treatment technology is known as phytoremediation, which receives the great interests of scientists in the world So far, a numerous number of studies on successful phytoremediation of wastewater polluted by phosphorus The most common types of plant species for nutrient removal are Typha latifolia, Cyperus papyrus, Phragmite australiis (Almuktar et al., 2018) TP removal efficiency of vi There are many ways to classify CWs which are based on water level, direction of water (Vymazal, 2008) Based on CWs water levels are classified into categories: Surface flow CWs, Subsurface flow CWs (VF-CWs, HF-CWs), Hybrid / integrated / combined CWs The water level in the SF system is higher than the substrate surface while it is equal to or lower than the substrate surface in the SSF system (Davis, 1995) Based on the flow direction of water, SSF is divided into types of horizontal flow (HF) and vertical flow (VF) Water in HFCWs flooded the substrate in the system before exiting through water level control While water in the VFCWs system drains with the intermittent application of water to the system (Stefanakis et al 2014) d Mechanisms of CWs for P removal Numerous studies shown that the phosphorus in constructed wetlands is removed mainly by absorption of plants, accumulation of microorganisms, absorption and precipitation of matrix (Lu, 2006) Firstly, the inorganic phosphorus is synthesized ATP, DNA and RNAetc.by uptake and assimilation of plants, and removed from the system through the plants harvested Secondly, phosphorus is necessary to microbial, phosphorus bacteria converted poorly soluble organic phosphorus and phosphorus to dissolved inorganic phosphorus which is conducive to absorption by plants Finally, phosphorusis removed by adsorption of media or ion exchange, the iron, aluminum, calcium compounds will affect the adsorption capacity of the media, and PAOs excess polyphosphate phosphorus also has a certain role to removal phosphorus Since the constructed wetland have a special aerobic and anaerobic conditions, PAOs can be adsorbed an excess of phosphorus in the aerobic state, and released excess phosphorus in anaerobic conditions, some of phosphorus will spread with the water transport, other will adsorption by the medium, because of the release of phosphorus, adsorption by media in favor of phosphorus in the local where concentration of phosphorus is higher Figure 1.2 P removal in CWs (Hristina Bodin, 2013) The most important way to remove phosphorus is adsorption and precipitation of matrix in constructed wetland system, there is less effect for plant adsorption of organic phosphorus, but the absorption of plant is given priority to remove inorganic phosphorus, which may be related to the large plants, like reed plants, need for inorganic phosphorus with a longterm growth.( LI jianbo, 2008) considered that: the adsorption by plants is a major way when at a low concentration of phosphorus, and the absorption by plants appear to be negligible when at a higher concentrations However, the adsorption of medium is limited, that is the absorption effect will be reduced after reaching saturation (Qin and Chen, 2016) 1.3.2 Influential factors and treatment performance a Influence factors Substrates (medium) The substrate is the critical design parameter in CWs and SSF CWs in particular, because it can provide a suitable growing medium for plant and also allow successful movement of wastewater (Kadlec and Wallace, 2009) Moreover, substrate sorption may play the most important role in absorbing various pollutants such as phosphorus (Ju et al., 2014) Selection of suitable substrates to use in CWs for industrial wastewater treatment is an important issue The selection of substrates is determined in terms of the hydraulic permeability and the capacity of absorbing pollutants Poor hydraulic conductivity would result in clogging of systems, severely decreasing the effectiveness of the system, and low adsorption by substrates could also affect the long-term removal performance of CWs (Wang et al., 2010) Many studies also suggest that substrates such as sand, gravel, and rock are the poor candidate for longterm phosphorus storage, but by contrast, artificial and industrial products with high hydraulic HRT (Hydraulic retention time) HRT determines the average contact time of microbial communities with pollutants (Lee et al., 2009) Furthermore, the effect of HRT may differ between CWs depending on the dominant plant species and temperature, as those factors can affect the hydraulic efficiency of wetlands HLR (Hydrologic loading rate) HLR is defined as following formular: 𝑞= 𝑄/𝐴 100 Where q is defined as the volume per time per unit area (cm day -1); A is the wetland surface area (m2), Q is the flow rate (m3 day-1) Avila et al (2014) also studied the feasibility of hybrid CW systems used for removing emerging organic contaminants, and demonstrated that the removal efficiency for most compounds decreased as the HLR increased (Yan and Xu, 2014; Huang et al., 2000) Feeding mode The influent feeding mode is another crucial design factor that can affect the performance of a wetland system (Zhang et al., 2012) Wetlands can be fed in continuous, batch, and intermittent modes These modes affect the oxidation and reduction conditions as well as the oxygen to be transferred and diffused in the system resulting in treatment efficiency modification 10 b P removal efficiency Table 1.5 P removal by Constructed Wetland Types of plants Environments Foxtail Grass, Flax Lily, Banksia, and Bottlebrush Pea gravel, sand, and loamy sand Lockport dolomite Queenston shale Typha P australis, T latifolia, P hydropiper, A sessilis, C esculenta and P stratoites J effuses C lurida D acuminatum Phragmites australis and cattails, Typha latifolia T.angustifolia, P.australis, S pungens Types of wastewater Synthetic strom water Sewage wastewater Fonthill sand Gravel Initial concentration (mgP/L) Removal (%) 4.51 mg/l 6-36 189 (mg/m2/d) 18 400-700 (mg/m2/d) 17-28 105-331 (mg m−2 day−1) 5-58 5.75 (mg/l) 76 77 Sand and clay Agricultural runoff 2.5 (mg/l) 85 74 10mg/l (P- PO43-) Gravel Paxton fine sandy loam soil Dairy cows 60 68 HFWs seem to be more effective in P elimination than VFWs because of the longer flowing distance and treatment time (Lüderitz and Gerlach, 2002) 11 1.4 Removal phosphorus by plants in the CWs 1.4.1 Classification of plants used in CWs a Role of plants in CWs Plants is one of factors will affect the performance of CWs Plants provide an environment for microorganisms to attach and release oxygen from the root system which affect removal efficiency of plants (Jethwa and Bajpai, 2016) Using green plants to reduce pollutant concentration in soil and water was defined as phytoremediation (“Phyto” meaning plants, “remediation” meaning to restore and clean) (Cunningham et al., 1997) Phytoremediation is more attractive than other technologies thanks to low maintenance, far-reaching, reducing pollution emissions, dust and by-products, preventing soil erosion, surface water flow, permeability, noise reduction, and increased aesthetics, carbon dioxide absorption, improved soil supply after treatment (Champagne, 2007) In addition, phytoremediation (phytoremediation) is economically viable According to Champagne (2007), this method is at least 40% cheaper than other onsite processing methods and 90% less than ex situ technologies b Classification of plants used in CWs Wetland plants can be categorized under four main classes, namely, emergent plants, floating leave macrophytes, submerged plants, and freely floating macrophytes Wu et al (2014) Macrophytes frequently used in CW treatments include emergent plants, submerged plants, floating leaved plants and free floating plants Although more than 150 macrophyte species have been used in CWs globally, only a limited number of these plant species are very often planted in CWs in reality Emergent species are Phragmitesspp (Poaceae), Typha spp (Typhaceae), Scirpus spp.(Cyperaceae), Iris spp (Iridaceae), Juncus spp (Juncaceae) and Eleocharis spp.(Spikerush) The most 12 frequently used submerged plants are Hydrilla verticillata, Ceratophyllum demersum, Vallisneria natans, Myriophyllum verticillatum and Potamogeton crispus The floating leaved plants are mainly Nymphaea tetragona, Nymphoides peltata, Trapa bispinosa and Marsilea quadrifolia The free-floating plants are Eichhornia crassipes, Salvinia natans, Hydrocharis dubia and Lemna minor In addition, Ornamental flowering plants, especially Canna indica (Sandoval et al., 2019) P.australis is the most common species in Asia and Europe while T latifolia is the most popular plant used in North America The most used plants in Africa are Cyperus papyrus L., P australis and Typha domingensis, Schoenoplectus tabernaemontani In Central and South Americas, Oceania, Palla was recored the most popular wetland plants Regarding types of the wetland plants used subsurface wetland, the second most common plant is Typha spp which is found in Australia, East Asia, North America, Africa In addition, P.australis is the most popular species globally (IWA Specialist Group 2000; Scholz 2006; Vymazal 2014) Common species used in HFCWs are Scirpus (lacustri, acutus, californicus and validus) Typha (domingensis, glauca, orientalis, latifolia and angustifolia), Bulrush and comment reeds Phragmites spp is the most popular (Vymazal, 2011) And most of them are herbaceous plants (Vymazal, 2011; Jethwa and Bajpai, 2016) Table 1.6 Plant species are used to treat swine wastewater Species Submerged plant Free floating plants Emergent plant Common name Science name Hydrilla Hydrilla verticilata Water milfoil Blyxa Myriophyllum spicatum Blyxa aubertii Water hyacinth Eichhornia crassipes Rootless duckweed Wolfia arrhiga Water lettuce Pistia stratiotes Water fern Cattails Salvinia spp Typha spp 13 1.4.2 Removal P mechanisms by plants a Removal P mechanisms and P removal efficiency of plants The roots use energy to get P into the tree through the cell membrane Other changes take place in rhizosphere affecting plant P uptake The roots secrete organic acids (citrate and oxalate) which increase the availability of P availability Amount of excreted organic acid, mycorrhizal fungi, root-zone microorganisms allow a plant to uptake P more from soil P is removed from the system by harvesting the plants (Brix 1997; Ma et al 2016) In fact, the CWs with plants are more effective (Vymazal, 2011; Tanner, 2001) Depending on the stage of the system, plants will contribute to various removal effects For immature CWs, the role of plants in eliminating P will not be clearly shown However, the P removal efficiency of the system can still be enhanced by plants through its indirect impact on the treatment conditions of the system (Tanner, 2001) In addition, phytoremediation (phytoremediation) is economically viable According to Champagne (2007), this method is at least 40% cheaper than other onsite processing methods and 90% less than ex situ technologies The removal efficiency of P of Typha latifolia, Canna indica, Phragmites australisdao is 0.06 -74.87%, 0.43 - 4.17, 0.56 - 36.7%, respectively under different conditions In the same research conditions, the efficiency of removing P of Cladium mariscus and Iris pseudacorus is 10% and 18% (Jesus et al., 2017) The treatment efficiency of the dominant species is 37, 53, 61% for Phragmites, Typha, Scirpus respectively (Vymazal, 2011) 14 Table 1.7 P removal efficiency by plants in CW (Jesus et al., 2017) CW type FWS VSSF Phragmites australis P uptake (%) 36.71 Phragmites australis 34.19 Phragmites australis 32.02 Phragmites australis 35.93 Typha latifolia Typha latifolia Typha latifolia Typha orientalis Phragmites australis Scirpus validus Iris pseudacorus Iris sibirica Iris sibirica Iris sibirica 35.53 42.54 74.87 14.31 10.76 32.27 34.17 13.19 13.19 13.19 Plant species Phragmites Australis HSSF SSF Canna indica Canna indica Phragmites australis Arundo donax Typha latifolia Arachis duranensis Cyperus alternifolius Philodendron hastatum Phalaris arundinacea Phalaris arundinacea Notes Source 1st year harvested 1st year unharvested 2nd year harvested 2nd year unharvested Zheng et al (2015) Zheng et al (2015) Zheng et al (2015) Zheng et al (2015) Tang et al (2008) Tang et al (2008) Tang et al (2008) Tang et al (2008) High nutrient Medium nutrient Low nutrient 0.7 0.43 0.56 0.36 0.06 10.4 Sara G Abdelhakeem , Samir A Aboulroos Cui et al (2015) Cui et al (2015) Meng et al (2014) Meng et al (2014) Meng et al (2014) Van et al (2015) 29.8 Van et al (2015) 29.8 Van et al (2015) 22 45.9 Lower input 3.1 Higher input Březinová and Vymazal (2015) Březinová and Vymazal (2015) b Plant selection criteria Factors affecting the removal efficiency of plants include differences in 15 species, growth conditions, root surface area, oxidizing supply capacity, type of waste water and rate of loading, ability to withstand, absorb pollutants, be resistant to flooding, huge biomass (Jesus et al., 2017) Fast growth The rapid growth of plants corresponded with high level of P Therefore, they uptake a significant amounts of nutrient during the period of their growth Harvesting their above parts is the way to remove nutrients from wastewater (Vymazal, 2007) Tolerant to continuous flooding Beside the requirement of wetland plants with huge biomass and well developed root system, the tolerance ability to flood affects the nutrient removal efficiency by plants (Almuktar, 2018) Tolerant to contaminant Plants can be affected by environment stresses because many pollutants are present in CWs The concentration of influences in wastewater is too high to exceed the capacity of plants which reduces the growth and survival of plants (Surrency, 1993) In addition, high levels of pollutants directly affect the ecosystem of CWs causing inhibition of plant growth, even causing the disappearences of plants (Wu et al., 2015) The high concentration of pollutants in water resulting in disadvantage of both treatment efficiency and plant survival Plant tolerance to the high concentration of pollutants is another important factor which is considered when selecting them for CWs (Almuktar, 2018) Ability to accumulate contaminant Wetlands plants are recognized as an important factor affecting water quality in CWs Absorption capacity of pollutants of plants contributes to CWs removal efficiency (Wu et al., 2015) Most common plants used in CWs are weedy plants, which not bring 16 economic value This study was conducted to find out whether the plants are both economically valuable and treat environmental pollution 17 CHAPTER 2: MATERIALS AND RESEARCH METHODOLOGY 2.1 Research object, scale, and scope 2.1.1 Research objects In this research, experiments to investigate influential factors on P removal by selected plants and those with CWs were conducted with synthetic wastewater The experiments to search for potential plants were carried out with soil This study investigated 05 types of plants, including Colocasia gigantean, Piper lolot, Sauropus androgynous, Cymbopogon citratu, and Ubon paspalum 2.1.2 Research scale & scope The experiments to evaluate influential factors and those with CWs were implemented at lab-scale The former was done at the laboratory of Master’s Program in Environmental Engineering (MEE), VNU Vietnam Japan University (VJU), whereas the latter was located on the roof of a residential building in Yen Hoa, Cau Giay, Hanoi Concerning wastewater quality, this study focused on the removal of ortho phosphate (P-PO43-) of investigated plants Besides, other environmental parameters, such as TSS, pH, BOD5, COD, TN, N-NH4+, TP, P-PO43- were measured to evaluate the composition of real swine wastewater In relation to plants, in the experiment to screen plants, the attention was paid to the content of phosphorus in the whole plant as well as in different parts of plants In experiments to explore influential factors, phosphorus removal rate was used as main indicator 18 2.2 Materials, chemicals and equipment 2.2.1 Materials a Plants The investigated plant Ubon paspalum was collected in a home garden in Dong Phong commune, Tien Hai district, Thai Binh province whereas Colocasia gigantean, Piper lolot, Sauropus androgynous, and Cymbopogon citrate were gathered in Quang Bi commune, Chuong My district, Hanoi City Depending on the purpose of experiments, the plants of different ages were utilized Table 2.1 The list of investigated plants Common name Lemongrass Science name Picture Location Cymbopogon citratus Piper lolot Piper sarmentosum Giant elephant Colocasia gigantea 19 Quang Bi commune, Thinh Da hamlet, Chuong My district, Hanoi city Star gooseberry Sauropus androgynus Ubon paspalum Ubon paspalum Dong Phong commune, Tien Hai Distric, Thai Binh province b Synthetic wastewater Synthetic wastewater was prepared accordingly the composition and characteristics the real swine wastewater collected from a pig farm, which was located in Luong Xa village, Nam Dien commune, Chuong My district, Ha Noi c Chemicals Tải FULL (75 trang): https://bit.ly/3dr31Jw Dự phòng: fb.com/TaiHo123doc.net KH2PO4, NH4Cl used in this study were of analytical grade and purchased from ESQ Co., Ltd (Ba Dinh, Hanoi) 2.2.2 Experimental design a Screening potential plants This experiment was to search for plants, which have potential for used in phytoremediation or CWs to eliminate phosphorus All investigated plants were grown in the soil They were harvested for determination of phosphorus content at the mature age In this experiment, phosphorus content and biomass growth rate were used for comparison purpose b Investigating influential factors All experiments were implemented with simulated swine wastewater First, the stock phosphorus solution (1000 mg P/L) was prepared by dissolving 4.39 g KH2PO4 into 1L of distilled water Then, the P stock solution was diluted 20 times to prepare 20 P working solution (50 mg P/ L) After that, the certain amount of NH4Cl was added to make the nutrient solution A (50 mg P/ L and 500 mg N/ L) Finally, the A solution was diluted four times to get the background nutrient solution B (12.5 mg P/ L and 125 mg N/ L) The experiments to investigate influential factors were carried out by varying the influential factors while using the same background nutrient solution (except the experiment to investigate effect of initial P concentration) Effect of initial phosphorus concentration: This experiment was designed to investigate how the plant can grow and uptake phosphorus in the solutions of different phosphorus concentrations This experiment was conducted with synthetic wastewater, which simulated 100%, 50 and 25% of real swine wastewater (P-PO4 50 mg/L, N-NH4-500 mg/L), in term of P and N This experiment included turns, each turn lasted for days, when the phosphorus in the solution was almost removed Cymbopogon citrate and 1.5-month Ubon paspalum were utilized for comparison 45 g of each plant was cultivated in a beaker containing 200 mL of nutrient solution The water sampling was done at the beginning of the experiment and after every days for determination of phosphorus concentration First, the water volume was measured Next, tape water was added for compensation of vaporization After that, mL of water was sampled for P analysis Tải FULL (75 trang): https://bit.ly/3dr31Jw Dự phòng: fb.com/TaiHo123doc.net Effect of pH: This experiment was to evaluate the influence of pH on phosphorus uptake and growth of two plants, namely Cymbopogon citrate and Ubon paspalum It was conducted with aqueous solutions of different pH values (3, 5, 7, 9, and 11) The pH value of the background nutrient solution was adjusted using H2SO4 and NaOH of various concentrations to ensure that the change in volume of the solution was negligible 2-week Cymbopogon citrate and 3-month Ubon paspalum were utilized The plant (60 g) was placed into a beaker containing 200 mL of the background nutrient solution This experiment comprised turns (2 days/ turn) At the start of experiment and after every days, water sample of mL was collected for P concentration and pH analysis Before sampling, the water volume left in the beaker was measured The status of plant was also recorded 21 Effect of plant age: The purpose of this test was to identify at which growth period, the plant is most efficient in phosphorus removal from wastewater This experiment was implemented with the background nutrient solution Ubon paspalum of kinds of age (1, 1.5, and months) and Cymbopogon citrate of kinds of age (baby and mature) were used This experiment lasted for turns (2 days/ turn) The water sampling was implemented the same as that for experiment to investigate the effect of pH Effect of plant density: The experiment was to determine the best plant density for plant growth and phosphorus accumulation This experiment was carried out in both soil and auqeous solutions For hydroponic experiments, three kinds of plant density, such as 1, 3, and plant(s)/ beaker were applied The water sampling was done in a similar procedure to that of experiments for pH and plant age For soil experiment, it was conducted only with Ubon paspalum with types of plant density (1, 3, and plants/ trough) The soil was fertilized times/ week, months after planting, the Ubon paspalum was harvested for determination of both P content and biomass growth Effect of water level: This experiment was to evaluate the ability of plant to adapt with different water levels It was done with kinds of water levels (2, 5, and cm) The water sampling frequency was the same as that of the experiment on pH, plant age, and density c Trial application of the selected plant in CWs CWs experiment setting up: The experiment was designed to include treatment systems in parallel In the systems 1&3, the horizontal flow constructed wetland was followed by the adsorption unit The wastewater was stored in a big sink, then pumped into the CWs using peristaltic pump (HV-77200-50, Masterflex ColeParmer, USA) To ensure that the effluent quality meets the requirement of discharge standard, after going through CWs, the wastewater was pumped into adsorption unit The systems 2&4 did not include adsorption units and used as the control systems 22 6789887 ...VIETNAM NATIONAL UNIVERSITY, HANOI VIETNAM JAPAN UNIVERSITY VU THI THOM STUDY ON POTENTIAL PLANTS FOR USE IN CONSTRUCTED WETLAND TO STRENGTHEN PHOSPHORUS TREATMENT PERFORMANCE FROM SWINE WASTEWATER... 1.3 Methods for handing and using liquids at systems Biogas Swine wastewater with treatment Settling pond Pouring into Swine fish pond wastewater without Discharge into treatment environment % m3... factors influencing the growth and utapke of phosphorus by plants The objectives of this study comprise (1) to search for potential plants for phosphorus decontamination from wastewater, (2) to