Nghiên cứu khả năng giảm đạm, lân của mồm mỡ (hymenachne acutigluma) trong nước thải ao nuôi thâm canh cá tra tt tiếng anh

MINISTRY OF EDUCATION AND TRAINING CAN THO UNIVERSITY SUMMARY OF THE PhD THESIS Major: Soil and water environment Code: 9440303 PhD STUDENT: LE DIEM KIEU THESIS TITLE STUDY ON NITROGEN AND PHOSPHORUS REMOVAL CAPACITY OF HYMENACHNE ACUTIGLUMA IN INTENSIVE STRIPED CATFISH AQUACULTURE WASTEWATER Can Tho, 2019 THE RESEARCH PROJECT WAS DONE AT CAN THO UNIVERSITY Supervisors: Associate Professor - Doctor Ngo Thuy Diem Trang Professor - Doctor Han Brix The doctorate degree dissertation is to be defended in front of a Specialized Committee at the state level at Can Tho University on ………………………………… Reviewer 1: Reviewer 2: The thesis can be referred at: - College of Environment and Natural Resources, Can Tho University - Learning Resource Center of Can Tho University - National Library of Vietnam ii LIST OF PUBLISHED WORKS Le Diem Kieu, Pham Quoc Nguyen, Ngo Thuy Diem Trang, Tran Thi Huynh Nhu, 2015 Evolution of nitrogen forms in wastewater of intensive catfish (Pangasianodon hypophthalmus) pond growing Hymenachne grass (Hymenachne acutigluma) Can Tho University Journal of Science (Environment and climate change): 80-87 ISSN: 1859-2333 Le Diem Kieu, Nguyen Thi Anh Đao, Le Quang Thuan, Huynh Nhu Y, Pham Quoc Nguyen, Hans Brix and Ngo Thuy Diem Trang, 2017 Effects of inorganic nitrogen forms on growth and nitrogen uptake capacity of Hymenachne acutigluma Can Tho University Journal of Science (Environment and climate change) (1): 100-109 ISSN: 18592333 Le Diem Kieu, Nguyen Van Na, Nguyen Thi Truc Linh, Pham Quoc Nguyen, Hans Brix and Ngo Thuy Diem Trang, 2017 Effects of plant density on growth and uptake of nitrogen and phosphorus of Hymenachne acutigluma Can Tho University Journal of Science (Environment and climate change)(1): 13-21 ISSN: 1859-2333 Le Diem Kieu, Ho Thanh Paul, Nguyen Xuan Loc, Pham Quoc Nguyen, Nguyen Van Cong and Ngo Thuy Diem Trang, 2017 The ability of constructed wetland systems with Hymenachne acutigluma, surface flow and aeration for treating wastewater from intensive catfish (Pangasianodon hypopthalmus) culture pond Science and technology journal of Agriculture and rural development 23: 89-96 ISSN: 1859-4581 Kieu L D., N V Dao, P Q Nguyen and N T.h Giao, 2018 Effects of nitrogen and phosphorus on growth of Hymenachne acutigluma and uptake of nitrogen and phosphorus containing wastewater form catfish (Pangasianodon hypophthalmus) pond Imperial Journal of Interdisciplinary Research (1): 74-81 ISSN: 2454-1362 Le Diem Kieu, Tran Tan Dat, Nguyen Xuan Loc, Pham Quoc Nguyen, Nguyen Van Cong and Ngo Thuy Diem Trang, 2018 The ability of free water surface constructed wetland systems with Hymenachne acutigluma for treating wastewater from intensive catfish (Pangasianodon hypopthalmus) Science and technology journal of Agriculture and rural development 5: 103-110 ISSN: 1859-4581 iii CHAPTER 1: INTRODUCTION 1.1 Introduction The Mekong Delta (MD) is the largest intensive culture area of Pangasius (Pangasianodon hypophthalmus) in Vietnam with 6,078 in 2017 (VASEP, 2018) The concentrations of NH4+-N, NO3 N, TN, PO43 P and TP in pond water were increased at the end of the culture period due to excreted waste and uneaten food (Huynh Truong Giang et al., 2008; Pham Quoc Nguyen et al., 2014) The average discharge wastewater volume of catfish ponds was 9,133.3 m3/tonne fish corresponding to 36.5 kg N and 9.1 kg P/tonne fish (Anh et al., 2010) and was not treated before being discharged into the environment (Cao Van Thich, 2008) In the past several decades, constructed wetlands (CWs) is well known as effective environmentally friendly technique for water pollution control in many countries in the world (Zhang et al., 2008 a, b) The macrophytes play important role in pollution control in the CWs treatment systems espeically uptake nitrogen (N) and phosphorus (P) (Brix, 1997; Vymazal, 2011) Hymenachne acutigluma is emergent plant which is found from the Northern to the Southern Vietnam (Pham Hoang Ho, 2003; Vo Van Chi, 2004) This plant had ability to grow in wastewater with high N and P concentrations (78.46-104.5 mg N/L, 8.67 mg P/L), and to remove 74.09% TN and 89.47% TP after 60 days (Bui Truong Tho, 2010) H acutigluma was popular grass for cattle in the MD with 2.52-2.86 tonnes dry weight/ha/45 days (Nguyen Thi Hong Nhan, 2010a) To our knowledge, limit information on N and P removal efficiency in wastewater from intensive catfish ponds of H acutigluma, therefore, the research in title “Study on nitrogen and phosphorus removal capacity of Hymenachne acutigluma in intensive striped catfish aquaculture wastewater” was conducted 1.2 Objectives General objectives: Contribute to reduce surface water pollution from intensive catfish farms in the Mekong Delta using phytoremediation technique Specific objectives - To determine required N, P concentrations and forms of dissolved inorganic nitrogen (ammonium, nitrate), which were suitable for the growth of H acutigluma; - To evaluate the effects of planting density on growth and uptake nitrogen and phosphorus in wastewater from intensive catfish of Hymenachne grass; - To determine the removal capability of free water surface flow (FWS) constructed wetlands planted H acutigluma based on nutrient requirement in pilot scale 1.3 The contents of the study - To evaluate N and P suitable demand for the growth and nutrient uptake of H acutigluma with single increment of N or P, N:P concentration ratios in the background solution of intensive catfish wastewater, which were conducted in the net house; - To evaluate forms of dissolved inorganic nitrogen NH4+-N: NO3 N (4:0, 3:1, 1:1, 3:1 and 0:4) for the growth and nutrient uptake of H acutigluma in the background solution of intensive catfish wastewater, which were conducted in the net house; - To evaluate the effects of planting density of H acutigluma on growth and N, P uptake in intensive catfish wastewater at the field; - To examine the feasibility of FWS CWs system planted H acutigluma, which operated with (1) batch loading and (2) continuous loading at the field 1.4 Signification of the thesis The results of the thesis were learning, reference and research sources on using plant to treat wastewater from intensive catfish farms and aquaculture These results indicated that H acutigluma had good potential use in CWs system for wastewater treatment from intensive catfish ponds 1.5 New findings of the thesis The thesis showed that N and P concentrations in the growth solution affected growth, development and N, P uptake ability of H acutigluma The suitable N and P concentrations, N:P and NH4+-N:NO3 N ratios for the good growth and N, P uptake of H acutigluma were identified in this thesis This was an important basis for determining the amount of N and P supply and facilitating the nitrification process in the CWs to treat wastewater from intensive catfish ponds The suitable planting density for good growth and N, P uptake of H acutigluma has been identified, which suggested an optimal plant density for the CWs wastewater treatment system The thesis found that the FWS CWs systems planted H acutigluma operated with batch loading and the 93-hour HRT was suitable for treating wastewater from intensive catfish ponds that located far from main river The continuous loading FWS CWs systems planted with H acutigluma also had a good treatment efficiency operated at 3.5- to 7-hour HRT The FWS CWs systems with the presence of H acutigluma did not require aeration These were important information for application of H acutigluma integrated in the FWS CWs systems to treat wastewater from intensive catfish farms and sustainably use surface water resources CHAPTER 2: LITTERATURE REVIEW 2.1 Characteristics of wastewater from intensive catfish ponds The average concentrations of TN, TAN, NO2 N, NO3 N, PO43 P and TP of water in intensive catfish ponds were 7.86-26.34, 0.033-7.56, 0.10-0.35, 0.03-0.9, 0.326-0.398 and 1.61-4.26 mg/L, respectively (Huynh Truong Giang et al., 2008; Nguyen Huu Loc, 2009; Pham Quoc Nguyen et al., 2014) The discharge wastewater volume of catfish ponds was 2,162,000 m3/ha/crop corresponding to 9,133.3 m3/tonne fish which contained 25.2-46.8 kg N and 9.9-18.4 kg P/tonne fish (Anh et al., 2010) The intensive catfish ponds located near large river had high frequent and amount of water exchange, therefore, 91,92-95,58% of N and P discharged in the wastewater (Anh et al., 2010) 2.2 Factors affecting the growth and N and P uptake of aquatic plants Nitrogen is about 1-5% of total dry matter of plant The growth of aquatic plants increases with the concentration of N in environment, but the plant biomass might be decreased when the N concentration is higher than the optimum concentration Higher plants can uptake and assimilate nitrogen as either NH4+-N or NO3 N, with some species showing a strong preference for one ionic form over the other (Kronzucker et al., 1997; Forde and Clarkson, 1999) Carex rostrata, Typha latifolia, Phragmites australis (Conlin and Crowder, 1989), S natans, S molesta, C involucratus and V zizanioides prefer NH4+-N to NO3 N (McFarland et al., 2004; Jampeetong and Brix, 2009) In addition, the demand and response of P concentrations are also different between plant species The N:P ratio in environment also affected aquatic plants growth such as Phragmites australis had the highest growth rate at 10-33 of N: P ratio (Romero et al., 1999) 2.3 Overview of Hymenachne acutigluma Scientific name of Hymenachne grass is Hymenachne acutigluma that distributed from the Northern to the Southern of Vietnam (Pham Hoang Ho, 2003; Vo Van Chi, 2004) Harvest dry biomass of Hymenachne grass was 282.91-297.33 tonnes/ha in field conditions This grass could grow in wastewater with TN, TP, COD and DO levels of 78.46, 8.76, 97.18 and 0.59 mg/L, and could help to remove 74.09% TN, 89.47% TP after 60 days (Truong Hoang Dan and Bui Truong Tho, 2012) CHAPTER 3: METHODOLOGY 3.1 Experimental period and site The research was carried out from March 2015 to November 2017 at Dong Thap University for experiments in the net house while the field experiments were conducted at catfish farms in Lap Vo, Tam Nong and Tan Hong districts, Dong Thap province 3.2 Studied objects Seeds and shoots of H acutigluma were collected from the field in Dong Thap province Wastewater of intensive catfish farms in Lap Vo, Tam Nong and Tan Hong districts, Dong Thap province 3.3 Materials and methods 3.3.1 Experimental design for study on the effects of N, P concentrations on growth and N, P uptake - Experiment 1.1: H acutigluma shoots were planted in intensive catfish wastewater with five levels of nitrogen concentration (5, 10, 20, 30 and 40 mg N/L) for 42 days - Experiment 1.2: H acutigluma shoots were planted in intensive catfish wastewater with five levels of phosphate concentration (1, 2, 4, and 10 mg P/L) for 42 days Hymenachne plants were placed in a 45 L plastic container (length x width x height of 60 x 40 x 24 cm) containing catfish wastewater added N, P to achieve the studied N, P levels They were arranged in a completely randomized design with three replications in the net house Plant growth measurements: shoot height, root length, number of leaves and new shoots were measured at every two weeks while plant biomass was measured at the beginning and at the end of the experiment Water samples were collected and analyzed NH4+-N, NO3 N, NO2 N, TKN, PO43 P, TP concentration at every two weeks The content of TKN, TP in plant samples were analyzed at the beginning and at the end of the experiment 3.3.2 Experimental design for study on the effects of N:P concentration ratio on growth and N, P uptake - Experiment 1.3: three levels of N (30, 60 and 120 mg/L) and three levels of P (5, 10 and 20 mg/L) were studied and they combined to the total nine combination treatments in hydroponic and sediment conditions The plastic pot (45 L) was planted with shoots (Fig 3.1A) Each treatment was replicated times (72 pots) and arranged in a completely randomized design (Fig 3.1B) for 42 days in the net house Plant growth measurements: shoot height, root length, number of leaves and new shoots were measured at every two weeks while plant biomass was measured at the beginning and at the end of the experiment - Experiment 1.4: the experimental design was completely randomized with treatments of three N, P enriched levels 60N:5P, 120N:5P, 180N:10P mg/L and control (no added N, P) H acutigluma was planted by seeds Each treatment was replicated times and arranged in a completely randomized design for 224 days in the net house Plant growth and development measurement: shoot height, number new of shoots, root length (Exp 1.3 and 1.4), flowers (Exp 1.4) were measured once every two weeks, root length and biomass were measured at the beginning and the end of the experiment Water samples were collected and analyzed NH4+-N, NO3 N, NO2 N, TKN, PO43 P, TP concentration once every two weeks; TKN, TP content of plants and sediment samples were analyzed at the beginning and at the end of the experiment Figure 3.1: Three H acutigluma shoots (A) planted in a pot, and (B) experimental design of N:P ratio study 3.3.3 Experimental design for study on the effects of NH4+-N:NO3-N concentration ratio on growth and N, P uptake - Experiment 2: H acutigluma shoots were planted in intensive catfish wastewater with five NH4-N:NO3-N concentration ratios (4:0, 3:1, 1:1, 3:1 and 0:4) of 120 mg N/L and mg P/L (Table 3.1) Each treatment was replicated 12 times and arranged in a completely randomized design in the net house Plant growth measurements: shoot height, root length, number of new shoots and biomass were measured at every two weeks Water, plants and sediment of replications were collected and analyzed for NH4+-N, NO2 N, NO3 N, TKN concentrations in water samples; and for NH4+-N, NO3 N and TKN content in plants and sediment at every weeks Table 3.1: Ratio, concentration, nitrogen compounds of NH4+-N and NO3 N of the treatments Concentration Nitrogen compounds NH4+-N:NO3 N (mg/L) Treatment Mol ratio + NH4 -N NO3 -N NH4+-N NO3 N 4:0 4:0 120 (NH4)2SO4 3:1 3:1 90 30 (NH4)2SO4 KNO3 1:1 1:1 60 60 NH4NO3 1:3 1:3 30 90 (NH4)2SO4 KNO3 0:4 0:4 120 KNO3 3.3.4 Experimental design for study on the effects of planting density on growth and N, P uptake - Experiment 3: there were four plant densities of 10, 20, 30, 40 shoots/m2 and control treatment (without plant) were arranged in a completely randomized design with 12 replications for each plant density treatment and replications for the control treatment The intensive catfish wastewater with 120 mg N/L (NH4+-N:NO3 N ratio 1:3) and mg P/L was used H acutigluma was planted in an experimental unit of m2 filled up with 0.6 m water and 12 cm sediment (Fig 3.2) in the field in Tan Hong district, Dong Thap province - Plant growth measurements: shoot height, root length, number of new shoots and biomass were measured at every two weeks - Collecting water, plants and sediment of random replications to analyze NH4+-N, NO3 N, NO2 N, TKN, PO43 P, TP concentrations in water samples and TKN, TP content of grass and sediment samples at every two weeks Figure 3.2: Experimental design for the study on the effects of planting density on growth and N, P uptake of H acutigluma 3.3.5 Experimental design for study on treatment efficiency of batch loading FWS CWs sytems planted H acutigluma treating intensive catfish wastewater 3.3.5.1 Preliminary experiment (Experiment 4.1) The experiment was designed with surface coverage of 0, 25, 50 and 75% area of FWS CWs systems (corresponding to 0, 18, 36 and 54 plants/m2) combined with and without aeration supplementation in replications for each treatment The experiment was conducted in Lap Vo district, Dong Thap province The FWS CWs was designed in pyramidal frustum shape with top area 1x1 m and bottom area 0.7x0.7 m and 1.15 m high (Fig 3.3) The water level in the CWs was 1.0 m made up 0.73 m3 per experimental unit The wastewater from catfish pond was pumped to the wetland systems Water samples were collected at interval times of 0, 3, 9, 21, 45 and 93 hours to analyze TSS, COD, DO, NH4+-N, NO3 N, NO2-N, TKN, PO43 P and TP concentrations 3.3.5.2 Experimental design for study on on treatment efficiency of batch loading FWS CWs sytems planted H acutigluma treating intensive catfish wastewater (Experiment 4.2) The FWS CWs was designed in length x width x depth of 10 x x 0.6 m with water level at 0.4 m (Fig 3.4) treating intensive catfish wastewater, which was arranged in a completely randomized design for replications There were two treatments of with H acutigluma plants (at density of 40 shoots/m2) and without plants (control treatment) operated with hydraulic retention time (HRT) of 93-hour (3.9 days) Influent and effluent samples were determined for DO, NH4+-N, NO3 N, NO2 N, TKN, PO43 P and TP concentrations at the first stage (16, 32, 48, 64 days) and the second stage (80, 96, 112, 128 days) - Shoot height, root length, number of new shoots, biomass and N, P content in plant tissue were measured at 64 days Figure 3.4 Diagram of the FWS CWs with H acutigluma operated in batch loading 3.3.6 Experimental design for study on on treatment efficiency of continuous loading FWS CWs planted H acutigluma treating intensive catfish wastewater (Experiment 5) - The experiment comprised of treatments with factors (1) vegetation (with and without plants) (60 shoots/m2), (2) hydraulic Table 4.1: N content (%) and N accumulation (mg/plants) of H acutigluma in different N concentration Treatments N content (%) N accumulation (mg/plant) 0.45±0.05b 6.72±2.15c N5 b 0.48±0.10 14.46±5.24bc N10 ab 0.54±0.05 39.49±12.85ab N20 a 0.66±0.04 54.81±15.69a N30 a 0.70±0.06 64.11±4.14a N40 Note: Values(Mean ± std, n=3) the different letters of a,b,c in the same columns indicated statistically signifcantly different at signficant (p