優養化水體中營養物質含量過高,為水庫水質下降的主要因素。 公共供水水庫特別容易受到優養化水質影響,營養物質含量過多會引起藻類迅速繁殖，導致飲用水處理過程中有藻毒素及異味問題。在藻類和植物所必需的營養物質中，磷是台灣水庫中限制藻類生長之主要營養物質，控制磷在水庫中的濃度為重要議題。現地水質淨化工法(On-Site Treatment, OST)，如礫間氧化及人工濕地，被普遍應用於台灣處理嚴重污染之排水與溪流，不過卻很少被應用於處理優養化水庫，原因之一為常用OST除磷效果普通，且大部分OST無法對優養化水庫不算高的磷濃度(TP < 0.02 mg/L)有再淨化效果。複合濾料水質淨化系統(Multi-Soil-Layering, MSL)改良自傳統土壤處理方法，具有過濾、攔除、吸附與鐵螯合沉積等除磷機制，且過去應用顯示MSL對於進流水總磷濃度有較高之寬容度。本研究於2019 年 8 月至 2021 年 5 月操作澎湖成功水庫BioNet+MSL試驗模場直接處理水庫原水，分析模場對優養化水庫原水總磷(Total Phosphorus, TP)、溶解磷 (Dissolved Phosphorus, DP) 及顆粒磷 (Particulate Phosphorus, PP) 的去除效率與可能機制。成功水庫TP濃度與PP比例及濁度相關，當水庫濁度高時，TP濃度與PP比例也隨之增高。此外，成功水庫的濁度變化主要受水庫庫容影響，水位越低水庫濁度越高。因此，MSL模場進流原水除了在夏季庫容高時PP與DP比例接近1:1外，其餘季節原水TP以PP為主(50-80%)。BioNET單元、MSL單元及全系統對磷的去除效果與原水TP濃度有關，當原水TP高於0.1 mg/L時(此時PP佔6成以上)，BioNET對磷的去除主要來自PP的過濾攔除 (25-45%)而DP去除率不到30%，MSL對磷的去除亦以PP居多(40-50%)，不過對DP的去除多了吸附及螯合沉積機制，使DP去除率達到40%。整體而言，BioNET做為前處理單元提供了30%左右的除TP效果(主要是PP)，而MSL做為核心單元可再去除45%的TP (PP略高於DP)，整個系統的TP、PP及DP的去除率分別為60%、65%及50%。當夏季TP低於0.1 mg/L時，全系統對TP、PP及DP的去除率降到50%，40%及50%，此時MSL的吸附及螯合沉積作用是系統出流水能否符合乙類標準的關鍵。不同季節及操作條件的試驗結果顯示當進流水pH偏低(<8)、水溫偏低(<20°C)、提高曝氣量及降低負荷率都對MSL的除磷效果沒有顯著影響。本研究於水質最差(TP>0.2 mg/L)的第5試程額外分析總有效磷(Total Reactive Phosphorus, TRP)及總有機磷(加酸及消化後可轉換為有效磷的有機磷及其他型態磷, TOP)，結果顯示水庫原水TOP略高於TRP，且TOP及TRP大多存在於顆粒態，且無論是BioNET或MSL單元對TRP的去除率都達到50%以上，而對TOP卻都不到30%，研判兩單元可能都缺乏足以分解有機磷及複合磷酸鹽的生物機制。

Eutrophication, the nutrient enrichment in a water body, is the main factor for water quality decline in artificial reservoirs. Reservoirs built for public water supply uses are particularly susceptible to the water quality effects of eutrophication, as excess nutrients trigger the excessive growth of algae, resulting in the development of algal toxins and odor problems for drinking water treatment. Among other nutrient compounds essential for algae and plants, phosphorus is commonly the key nutrient which limits the growth of algae in reservoirs of Taiwan. Because the concentrations of total phosphorus (TP) in reservoirs are much lower than TP in wastewater or polluted rivers, as well as the most On-site treatment (OST) methods are lacking a reliable removal efficiency in nutrients, none of the OST methods have been applied for the directly control of TP in water supply reservoirs. The multi-soil-layering (MSL) system is a new OST method modified from the traditional soil treatment process. Compared to existing OST methods, previous studies show that MSL system has advantages in simultaneous removal of organic matters and phosphorus from wastewater, having higher loading rate than traditional soil methods, and treating wastewater with a wide range of contamination levels. The EPA’s MSL pilot-plant in Chengkung Reservoir (Penghu), abbreviated as CKR, was investigated with an aim to understand the performance and mechanisms of removing phosphorus from a nutrient-enriched water supply reservoir. The pilot scale MSL system, operated since early 2019, consists of a BioNET process followed by four separate MSL experimental tanks. The removal efficiencies of TP, dissolved phosphorus (DP), and particulate phosphorus (PP) are analyzed by data collected from August 2019 to May 2021. Distinguishing composition between DP and PP during TP measurement is important as they determine the possible mechanism of phosphorus removal in the treatment system. The result showed that TP from CKR raw water is mostly made up of PP (50 – 80%). As PP contributes to turbidity (TB), and turbidity associated with CKR water level (WL), initial TP concentration is strongly correlated with TB and WL as well. BioNET performance in TP removal ranging between 9 – 34%. BioNET have a better removal in PP since there was not particular mechanism for DP removal provided within the system. The MSL system successfully provided 40 – 45% of TP removal. Soil and iron particles are enhancing DP removal mechanism, and thus it further improves TP removal in MSL system. Applying different setting of hydraulic loading rate and aeration in MSL system did not significantly affect TP removal, as well as water temperature and pH. Instead, study discovered that initial concentration could enhance TP removal performance of the entire system. The overall performance of the pilot plant from round 3 to round 5 are 50%, 60% and 60%, respectively under initial TP <0.1 mgL-1, 0.1 – 0.15 mgL-1, and >0.2 mgL-1. Increase of TP removal rate attributed to increase of removal capacity of the system, particularly in filtration process. In the fifth test run, total available phosphorus (TRP) and total organic phosphorus (TOP) and organic phosphorus that can be converted into available phosphorus after acid addition and digestion (TAHP) were additionally analyzed. The results show that the TOP+TAHP of the CKR raw water is higher than the TRP, both fractions mostly exist in the particulate form. The removal rate of TRP by either BioNET or MSL unit is more than 50%, but for TOP Less than 30%, the study concluded that the two units may lack sufficient biological mechanisms to decompose organophosphorus and complex phosphate.

[1] G. D. Cooke, E. B. Welch, S. Peterson, and S. A. Nichols, Restoration and Management of Lakes and Reservoirs Third Edition, 3rd Editio. Boca Raton: CRC Press, 2016. doi: https://doi.org/10.1201/9781420032109.
[2] C. F. Mason, Biology of Freshwater Pollution, 2nd editio. Longman, 1991.
[3] S. R. Carpenter, N. F. Caraco, D. L. Correll, R. W. Howarth, A. N. Sharpley, and V. H. Smith, “Nonpoint pollution of surface waters with phosphorus and nitrogen,” Ecological Applications, vol. 8, no. 3, pp. 559–568, 1998, doi: 10.1890/1051-0761(1998)008[0559:NPOSWW]2.0.CO;2.
[4] D. W. Schindler, S. R. Carpenter, S. C. Chapra, R. E. Hecky, and D. M. Orihel, “Reducing phosphorus to curb lake eutrophication is a success,” Environmental Science and Technology, vol. 50, no. 17, pp. 8923–8929, 2016, doi: 10.1021/acs.est.6b02204.
[5] H. Wang and H. Wang, “Mitigation of lake eutrophication: Loosen nitrogen control and focus on phosphorus abatement,” Progress in Natural Science, vol. 19, no. 10, pp. 1445–1451, Oct. 2009, doi: 10.1016/j.pnsc.2009.03.009.
[6] M. Jansson, “Enzymatic release of phosphate in water from subarctic lakes in Northern Sweden,” Hydrobiologia, vol. 56, no. 2, pp. 175–180, 1977, doi: 10.1007/BF00023356.
[7] M. Søndergaard, J. P. Jensen, and E. Jeppesen, “Retention and Internal Loading of Phosphorus in Shallow, Eutrophic Lakes,” vol. 1, pp. 427–442, 2001, doi: 10.1100/tsw.2001.72.
[8] P. Boonsook et al., “A comparative study of permeable layer materials and aeration regime on efficiency of multi-soil-layering system for domestic wastewater treatment in Thailand,” Soil Science and Plant Nutrition, vol. 49, no. 6, pp. 873–882, 2003, doi: 10.1080/00380768.2003.10410350.
[9] T. Wakatsuki, H. Esumi, and S. Omura, “High performance and N and P-removable on-site domestic waste water treatment system by multi-soil-layering method,” Water Science and Technology, vol. 27, no. 1, pp. 31–40, 1993, doi: 10.2166/wst.1993.0010.
[10] P. Song et al., “Treatment of rural domestic wastewater using multi-soil-layering systems: Performance evaluation, factorial analysis and numerical modeling,” Science of the Total Environment, vol. 644, pp. 536–546, Dec. 2018, doi: 10.1016/j.scitotenv.2018.06.331.
[11] S. Unno, T. Wakatsuki, T. Masunaga, and K. Iyota, “Study on Direct Treatment of River by Multi-Soil-Layering Method of Water Purification and Its Characteristics of Water Purification.,” Doboku Gakkai Ronbunshu, no. 726, pp. 121–129, 2003, doi: 10.2208/jscej.2003.726_121.
[12] K. Sato et al., “Treatment of Bio-genic Wastewater by Multi-Soil-Layering Method: Effect of Various Positions of Aeration Using Small Model Systems,” Japanese Journal of Soil Science and Plant Nutrition, vol. 76, no. 4, pp. 449–458, 2005, doi: 10.20710/dojo.76.4_449.
[13] X. Chen, K. Sato, T. Wakatsuki, and T. Masunaga, “Effect of aeration and material composition in soil mixture block on the removal of colored substances and chemical oxygen demand in livestock wastewater using multi-soil-layering systems,” Soil Science and Plant Nutrition, vol. 53, no. 4, pp. 509–516, 2007, doi: 10.1111/j.1747-0765.2007.00156.x.
[14] Supriyadi, H. Widijanto, Pranoto, and A. Dewi, “Improving quality of textile wastewater with organic materials as multi soil layering,” in IOP Conference Series: Materials Science and Engineering, 2016, vol. 107, no. 1. doi: 10.1088/1757-899X/107/1/012016.
[15] M. FAJRI, R. ZEIN, R. LDA, S. NINGSIH, and Z. FA, “Multi Soil Layering (MSL) System for Treatment of Noodle Industry Wastewater,” 2017, pp. 1–5. doi: 10.15224/978-1-63248-136-8-21.
[16] G. Yidong, C. Xin, Z. Shuai, and L. Ancheng, “Performance of multi-soil-layering system (MSL) treating leachate from rural unsanitary landfills,” Science of the Total Environment, vol. 420, pp. 183–190, Mar. 2012, doi: 10.1016/j.scitotenv.2011.12.057.
[17] P. Song et al., “Exploring the decentralized treatment of sulfamethoxazole-contained poultry wastewater through vertical-flow multi-soil-layering systems in rural communities,” Water Research, vol. 188, Jan. 2021, doi: 10.1016/j.watres.2020.116480.
[18] T. Wakatsuki, H. Esumi, and S. Omura, “High Performance On-site Domestic Waste Water Treatment System by Multi-Soil-Layering Method,” Japan journal of water pollution research, vol. 14, no. 10, pp. 709-719,656, 1991, doi: 10.2965/jswe1978.14.709.
[19] S. Luanmanee, P. Boonsook, T. Attanandana, and T. Wakatsuki, “Effect of organic components and aeration regimes on the efficiency of a multi-soil-layering system for domestic wastewater treatment,” Soil Science and Plant Nutrition, vol. 48, no. 2, pp. 125–134, 2002, doi: 10.1080/00380768.2002.10409182.
[20] T. Masunaga, K. Sato, J. Mori, M. Shirahama, H. Kudo, and T. Wakatsuki, “Characteristics of wastewater treatment using a multi-soil-layering system in relation to wastewater contamination levels and hydraulic loading rates: Original article,” Soil Science and Plant Nutrition, vol. 53, no. 2, pp. 215–223, 2007, doi: 10.1111/j.1747-0765.2007.00128.x.
[21] X. Chen, A. C. Luo, K. Sato, T. Wakatsuki, and T. Masunaga, “An introduction of a multi-soil-layering system: a novel green technology for wastewater treatment in rural areas,” Water and Environment Journal, vol. 23, no. 4, pp. 255–262, 2009, doi: https://doi.org/10.1111/j.1747-6593.2008.00143.x.
[22] E. R. Weiner, Applications of Environmental Aquatic Chemistry: A Practicacl Guide, 3rd Editio. Boca Raton: CRC Press, 2013. doi: https://doi.org/10.1201/b12963.
[23] T. Yindong et al., “Lake warming intensifies the seasonal pattern of internal nutrient cycling in the eutrophic lake and potential impacts on algal blooms,” Water Research, vol. 188, Jan. 2021, doi: 10.1016/j.watres.2020.116570.
[24] H. Zeng et al., “Water quality change and influencing factors in Lake Hongfeng (Guizhou Province), 2009-2018,” Journal of Lake Sciences, vol. 32, no. 3, pp. 676–687, 2020, doi: 10.18307/2020.0308.
[25] C. Hu, F. Li, N. Yang, Y. H. Xie, X. S. Chen, and Z. M. Deng, “Testing the Growth Rate Hypothesis in Two Wetland Macrophytes Under Different Water Level and Sediment Type Conditions,” Frontiers in Plant Science, vol. 11, Aug. 2020, doi: 10.3389/fpls.2020.01191.
[26] C. Penn and J. M. Bowen, Design and construction of phosphorus removal structures for improving water quality. 2017. doi: 10.1007/978-3-319-58658-8.
[27] S. M. Saia, H. J. Carrick, A. R. Buda, J. M. Regan, and M. Todd Walter, “Critical review of polyphosphate and polyphosphate accumulating organisms for agricultural water quality management,” Environmental Science and Technology, vol. 55, no. 5. pp. 2722–2742, 2021. doi: 10.1021/acs.est.0c03566.
[28] S. L. Xiang and W. bin Zhou, “Phosphorus forms and distribution in the sediments of Poyang Lake, China,” International Journal of Sediment Research, vol. 26, no. 2, pp. 230–238, Jun. 2011, doi: 10.1016/S1001-6279(11)60089-9.
[29] B. Y. A. Spivakov, T. A. Maryutina, and H. Muntau, “Phosphorus speciation in water and sediments (Technical Report),” Pure and Applied Chemistry, vol. 71, no. 11, pp. 2161–2176, 1999, doi: 10.1351/pac199971112161.
[30] M. L. Silveira and G. A. O’Connor, “Temperature effects on phosphorus release from a biosolids-amended soil,” Applied and Environmental Soil Science, vol. 2013, 2013, doi: 10.1155/2013/981715.
[31] D. W. Schindler et al., “Eutrophication of lakes cannot be controlled by reducing nitrogen input: Results of a 37-year whole-ecosystem experiment,” Proceedings of the National Academy of Sciences of the United States of America, vol. 105, no. 32, pp. 11254–11258, 2008, doi: 10.1073/pnas.0805108105.
[32] H. Roques, Chemical water treatment: principles and practice. Weinheim: VCH, 1996. doi: 10.1016/s0022-1694(97)89474-7.
[33] D. Palakkeel Veetil, E. C. Arriagada, C. N. Mulligan, and S. Bhat, “Filtration for improving surface water quality of a eutrophic lake,” Journal of Environmental Management, vol. 279, p. 111766, 2021, doi: 10.1016/j.jenvman.2020.111766.
[34] A. Kellil and D. Bensafia, “Removal of phosphates by direct filtration on sand bed,” Revue des Sciences de l’Eau, vol. 16, no. 3, pp. 317–332, 2003, doi: 10.7202/705510ar.
[35] R. O. A. Adelagun, “Technological Options for Phosphate Removal and Recovery from Aqua System: A Review,” Chem Sci Rev Lett, vol. 2016, no. 18, pp. 19–34, 2016.
[36] G. R. Liu, C. S. Ye, J. H. He, Q. Qian, and H. Jiang, “Lake sediment treatment with aluminum, iron, calcium and nitrate additives to reduce phosphorus release,” Journal of Zhejiang University: Science A, vol. 10, no. 9, pp. 1367–1373, Sep. 2009, doi: 10.1631/jzus.A0920028.
[37] K. M. Pilgrim and P. L. Brezonik, “Treatment of lake inflows with alum for phosphorus removal,” Lake and Reservoir Management, vol. 21, no. 1, pp. 1–9, 2005, doi: 10.1080/07438140509354407.
[38] B. Barçante, N. O. Nascimento, T. F. G. Silva, L. A. Reis, and A. Giani, “Cyanobacteria dynamics and phytoplankton species richness as a measure of waterbody recovery: Response to phosphorus removal treatment in a tropical eutrophic reservoir,” Ecological Indicators, vol. 117, p. 106702, Oct. 2020, doi: 10.1016/j.ecolind.2020.106702.
[39] Y. Liu, K. Tian, and A. Winks, “Phoslock, a soluble phosphorus binding technology, application in Lake Dianchi eutrophic water purification,” in Proceedings - 2009 International Conference on Environmental Science and Information Application Technology, ESIAT 2009, 2009, vol. 1, pp. 708–711. doi: 10.1109/ESIAT.2009.551.
[40] A. D. Steinman and M. Ogdahl, “Ecological Effects after an Alum Treatment in Spring Lake, Michigan,” Journal of Environmental Quality, vol. 37, no. 1, pp. 22–29, Jan. 2008, doi: 10.2134/jeq2007.0142.
[41] S. Shardendu, D. Sayantan, D. Sharma, and S. Irfan, “Luxury Uptake and Removal of Phosphorus from Water Column by Representative Aquatic Plants and Its Implication for Wetland Management,” ISRN Soil Science, vol. 2012, pp. 1–9, Feb. 2012, doi: 10.5402/2012/516947.
[42] K. Thongkao, M. Sudhadham, K. Suwannahong, and C. Wanna, “The Development of Nitrogen and Phosphorus Removal System on Eutrophication in Water Bodies Using Floating Plants,” in ACM International Conference Proceeding Series, Mar. 2020, pp. 32–35. doi: 10.1145/3386762.3386774.
[43] A. P. Davis, M. Shokouhian, H. Sharma, and C. Minami, “Water Quality Improvement through Bioretention Media: Nitrogen and Phosphorus Removal,” Water Environment Research, vol. 78, no. 3, pp. 284–293, 2006, doi: 10.2175/106143005x94376.
[44] Y. Zhang, F. He, S. Xia, Q. Zhou, and Z. Wu, “Studies on the treatment efficiency of sediment phosphorus with a combined technology of PCFM and submerged macrophytes,” Environmental Pollution, vol. 206, pp. 705–711, Nov. 2015, doi: 10.1016/j.envpol.2015.08.018.
[45] M. T. Brown, T. Boyer, R. J. Sindelar, S. Arden, A. Persaud, and S. Brandt-Williams, “A Floating Island Treatment System for the Removal of Phosphorus from Surface Waters,” Engineering, vol. 4, no. 5, pp. 597–609, Oct. 2018, doi: 10.1016/j.eng.2018.08.002.
[46] S. Yu, C. Miao, H. Song, Y. Huang, W. Chen, and X. He, “Efficiency of nitrogen and phosphorus removal by six macrophytes from eutrophic water,” International Journal of Phytoremediation, vol. 21, no. 7, pp. 643–651, 2019, doi: 10.1080/15226514.2018.1556582.
[47] L. Yang, H. T. Chang, and M. N. lo Huang, “Nutrient removal in gravel- and soil-based wetland microcosms with and without vegetation,” Ecological Engineering, vol. 18, no. 1, pp. 91–105, Oct. 2001, doi: 10.1016/S0925-8574(01)00068-4.
[48] J. A. Amador and G. W. Loomis, “The Soil Environment,” in Soil‐based Wastewater Treatment, John Wiley & Sons, Ltd, 2018, pp. 93–129. doi: https://doi.org/10.2134/sbwtreatment.c4.
[49] V. Tzanakakis, N. v Paranychianaki, and A. Angelakis, “Soil as a wastewater treatment system: Historical development,” Water Science & Technology: Water Supply, vol. 7, no. 1, pp. 67–75, 2007, doi: 10.2166/ws.2007.008.
[50] S. O. Skipton and E. Educator, “Residential Onsite Wastewater Treatment : The Role of Soil,” no. May, 2011.
[51] G. W. Loomis, “Soil Based Wastewater Treatment,” 2015. go.ncsu.edu/readext?356837 (accessed Feb. 16, 2021).
[52] EPA, “Onsite Wastewater Treatment System Manual,” Environmental Protection, no. February, pp. 1–367, 2002.
[53] Q. Yan, Y. Wang, L. Zhang, B. Zhu, and R. Zhang, “Treatment of domestic wastewater using composite ecological system in Chinese rural area,” International Journal of Environmental Technology and Management, vol. 17, no. 5, pp. 365–376, 2014, doi: 10.1504/IJETM.2014.064576.
[54] S. Kuniaki, I. H. A. Yoshihisa, and L. Suphakarn, “Long term on-site experiments and mass balances in waste water treatment by multi-soil-layering system,” no. 55, pp. 1–10, 2000.
[55] C. J. An et al., “Multi-soil-layering systems for wastewater treatment in small and remote communities,” Journal of Environmental Informatics, vol. 27, no. 2, pp. 131–144, 2016, doi: 10.3808/jei.201500328.
[56] S. Luanmanee et al., “Treatment of Domestic Wastewater With a Multi-Soil-Layering ( Msl ) System in a Temperate and a Tropical Climate,” Food and Fertilizer Technology Center, vol. 519, no. 1, pp. 1–8, 2002.
[57] K. Sato, N. Iwashima, T. Wakatsuki, and T. Masunaga, “Quantitative evaluation of treatment processes and mechanisms of organic matter, phosphorus, and nitrogen removal in a multi-soil-layering system,” Soil Science and Plant Nutrition, vol. 57, no. 3, pp. 475–486, 2011, doi: 10.1080/00380768.2011.590944.
[58] K. Sato, T. Masunaga, and T. Wakatsuki, “Water Movement Characteristics in a Multi-Soil-Layering System,” Soil Science and Plant Nutrition, vol. 51, no. 1, pp. 75–82, 2005, doi: 10.1111/j.1747-0765.2005.tb00009.x.
[59] K. Sato, T. Masunaga, and T. Wakatsuki, “Characterization of Treatment Processes and Mechanisms of COD, Phosphorus and Nitrogen Removal in a Multi-Soil-Layering System,” Soil Science and Plant Nutrition, vol. 51, no. 2, pp. 213–221, 2005, doi: 10.1111/j.1747-0765.2005.tb00025.x.
[60] E. F. Lowe, L. E. Battoe, D. L. Stites, and M. F. Coveney, “Particulate phosphorus removal via wetland filtration: An examination of potential for hypertrophic lake restoration,” Environmental Management, vol. 16, no. 1, pp. 67–74, Jan. 1992, doi: 10.1007/BF02393909.
[61] T. U. Jeong, K. H. Chu, S. J. Kim, J. Lee, K. J. Chae, and M. H. Hwang, “Evaluation of foam-glass media in a high-rate filtration process for the removal of particulate matter containing phosphorus in municipal wastewater,” Journal of Environmental Management, vol. 239, pp. 159–166, Jun. 2019, doi: 10.1016/j.jenvman.2019.03.064.
[62] C. Liu and P. M. Huang, “Kinetics of phosphate adsorption on iron oxides formed under the influence of citrate,” Canadian Journal of Soil Science, vol. 80, no. 3, pp. 445–454, 2000, doi: 10.4141/S99-079.
[63] S. A. Crosby, E. I. Butler, D. R. Turner, M. Whltfield, D. R. Glasson, and G. E. Millward, “Phosphate adsorption onto iron oxyhydroxides at natural concentrations,” Environmental Technology Letters, vol. 2, no. 8, pp. 371–378, 1981, doi: 10.1080/09593338109384064.
[64] J. Ma, J. H. Lenhart, J. Pedrick, and K. Tracy, “Stormwater phosphorus removal using an innovative filtration media,” in World Environmental and Water Resources Congress 2010: Challenges of Change - Proceedings of the World Environmental and Water Resources Congress 2010, 2010, pp. 1503–1511. doi: 10.1061/41114(371)159.
[65] S. Ramalingam and V. Chandra, “Effect of Water Temperature on Suspended Sediment Concentration and Particle Size in Ionized Water,” Iranian Journal of Science and Technology - Transactions of Civil Engineering, vol. 44, pp. 355–360, Oct. 2020, doi: 10.1007/s40996-020-00460-3.
[66] Y. v. Gutin and V. A. Zhuzhikov, “The effect of suspension concentration on filtration rate,” Chemical and Petroleum Engineering, vol. 7, no. 1, pp. 32–35, Jan. 1971, doi: 10.1007/BF01139813.
[67] M. River and C. J. Richardson, “Particle size distribution predicts particulate phosphorus removal,” Ambio, vol. 47, pp. 124–133, Jan. 2018, doi: 10.1007/s13280-017-0981-z.
[68] M. D. Munn et al., “Understanding the Influence of Nutrients on Stream Ecosystems in Agricultural Landscapes: U.S. Geological Survey Circular 1437,” Reston, Virginia, 2018. doi: https://doi.org/10.3133/cir1437.
[69] Jan R. Dojlido and Gerald A. Best, Chemistry of water and water pollution, Ellis Horw. Chichester: Ellis Horwood Limited, 1993. doi: 10.1016/0160-4120(95)80001-8.
[70] Q. Hou, P. Meng, H. Pei, W. Hu, and Y. Chen, “Phosphorus adsorption characteristics of alum sludge: Adsorption capacity and the forms of phosphorus retained in alum sludge,” Materials Letters, vol. 229, pp. 31–35, Oct. 2018, doi: 10.1016/j.matlet.2018.06.102.
[71] M. Ross, “What every operator should know about biological phosphorus removal,” Water Environment & Technology, Alexandria, Va, pp. 48–50, Jul. 2013. [Online]. Available: https://www.wef.org/MAGAZINE
[72] E. Valsami-Jones, Phosphorus in Environmental Technology: Principles and Applications. IWA Publishing, 2005. doi: 10.2166/9781780402758.
[73] Y. J. Wu, Y. W. Liu, H. H. Cheng, C. W. Ke, T. F. Lin, and L. M. Whang, “Biological pre-treatment system for ammonia removal from slightly contaminated river used as a drinking water source,” Process Safety and Environmental Protection, vol. 147, pp. 385–391, Mar. 2021, doi: 10.1016/j.psep.2020.09.042.
[74] D. C. Montgomery, G. C. Runger, and N. F. Hubele, Engineering Statistics, SI Version, 5th ed. Phoenix: John Wiley & Sons, Ltd, 2012.
[75] Y. Y. Liu and Y. L. Wang, “Application of stepwise cluster analysis in medical research.,” Scientia Sinica, vol. 22, no. 9, pp. 1082–1094, Sep. 1979, doi: 10.1360/ya1979-22-9-1082.
[76] G. Huang, “A stepwise cluster analysis method for predicting air quality in an urban environment,” Atmospheric Environment. Part B, Urban Atmosphere, vol. 26, no. 3, 1992, doi: 10.1016/0957-1272(92)90010-P.
[77] W. Sun, G. H. Huang, G. Zeng, X. Qin, and X. Sun, “A stepwise-cluster microbial biomass inference model in food waste composting,” Waste Management, vol. 29, no. 12, pp. 2956–2968, Dec. 2009, doi: 10.1016/j.wasman.2009.06.023.
[78] X. Wang, G. Huang, S. Zhao, and J. Guo, “An open-source software package for multivariate modeling and clustering: applications to air quality management,” Environmental Science and Pollution Research, vol. 22, no. 18, pp. 14220–14233, 2015, doi: 10.1007/s11356-015-4664-7.
[79] X. Wang, “rSCA: An R Package for Stepwise Cluster Analysis,” 2020.
[80] L. M. Mosley, B. Zammit, A. M. Jolley, and L. Barnett, “Acidification of lake water due to drought,” Journal of Hydrology, vol. 511, pp. 484–493, Apr. 2014, doi: 10.1016/j.jhydrol.2014.02.001.
[81] S. Li, R. T. Bush, R. Mao, L. Xiong, and C. Ye, “Extreme drought causes distinct water acidification and eutrophication in the Lower Lakes (Lakes Alexandrina and Albert), Australia,” Journal of Hydrology, vol. 544, pp. 133–146, Jan. 2017, doi: 10.1016/j.jhydrol.2016.11.015.
[82] P. Huovinen, J. Ramírez, L. Caputo, and I. Gómez, “Mapping of spatial and temporal variation of water characteristics through satellite remote sensing in Lake Panguipulli, Chile,” Science of the Total Environment, vol. 679, pp. 196–208, Aug. 2019, doi: 10.1016/j.scitotenv.2019.04.367.
[83] M. A. Shanafield, R. B. Susfalk, and K. C. Taylor, “Spatial and temporal patterns of nearshore clarity in Lake Tahoe from fine resolution turbidity measurements,” Lake and Reservoir Management, vol. 26, no. 3, pp. 178–184, Sep. 2010, doi: 10.1080/07438141.2010.504064.
[84] G. G. Braga et al., “Influence of extended drought on water quality in tropical reservoirs in a semiarid region,” Acta Limnologica Brasiliensia, vol. 27, no. 1, pp. 15–23, 2015, doi: 10.1590/S2179-975X2214.
[85] C. A. Pott, S. O. Jadoski, B. Schmalz, G. Hörmann, and N. Fohrer, “Temporal variability of nitrogen and phosphorus concentrations in a german catchment: Water sampling implication,” Revista Brasileira de Engenharia Agrícola e Ambiental, vol. 18, no. 8, pp. 811–818, 2014, doi: 10.1590/1807-1929/agriambi.v18n08p811-818.
[86] S. P. Chang and C. G. Wen, “Changes in water quality in the newly impounded subtropical feitsui reservoir, taiwan,” Journal of the American Water Resources Association, vol. 33, no. 2, pp. 343–357, 1997, doi: 10.1111/j.1752-1688.1997.tb03514.x.
[87] Z. Sharip, F. M. Yusoff, and A. Jamin, “Seasonal water quality and trophic status of shallow lentic waters and their association with water levels,” International Journal of Environmental Science and Technology, vol. 16, no. 8, pp. 4851–4862, Aug. 2019, doi: 10.1007/s13762-018-2172-2.
[88] C. E. Boyd, Water Quality, no. Rosborg 2015. Cham: Springer International Publishing, 2020. doi: 10.1007/978-3-030-23335-8.
[89] T. Pokavanich and Y. Alosairi, “Measurement of seasonal variability of hydro-environmental characteristics of Kuwait Bay,” Arabian Journal of Geosciences, vol. 9, no. 16, Oct. 2016, doi: 10.1007/s12517-016-2682-5.
[90] H. E. Hudson, “Factors Affecting Filtration Rates,” Journal - American Water Works Association, vol. 50, no. 2, pp. 271–277, Feb. 1958, doi: 10.1002/j.1551-8833.1958.tb15590.x.
[91] A. R. Prestigiacomo et al., “Apportionment of bioavailable phosphorus loads entering Cayuga Lake, New York,” Journal of the American Water Resources Association, vol. 52, no. 1, pp. 31–47, 2016, doi: 10.1111/1752-1688.12366.
[92] J. Shen et al., “Biophysiological and factorial analyses in the treatment of rural domestic wastewater using multi-soil-layering systems,” Journal of Environmental Management, vol. 226, pp. 83–94, Nov. 2018, doi: 10.1016/j.jenvman.2018.08.001.
[93] C. Report, “CHEMISTRY OF NITROGEN AND PHOSPHORUS IN WATER,” Journal (American Water Works Association), vol. 62, no. 2, pp. 127–140, Mar. 1970, [Online]. Available: http://www.jstor.org/stable/41265874