Influence of Enhanced Bioretention Media and Tropical Shrub on Nutrient Removal for Urban Runoff In Mixed Development Area

Goh , Hui Weng (2016) Influence of Enhanced Bioretention Media and Tropical Shrub on Nutrient Removal for Urban Runoff In Mixed Development Area. PhD thesis, Universiti Sains Malaysia.

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    Abstract

    Input nutrien daripada aliran air bandar terutamanya nitrogen (N) dan fosforus (P), merupakan masalah utama dalam perlindungan ekosistem akuatik. Kajian makmal ini bertujuan menyiasat penambahbaikan sistem bioretention untuk mengetahui prestasi dan mengoptimumkan komposisi bahan tambahan dalam media bioretention bagi menyingkirkan nutrien, dan menyiasat potensi fitopemulihan Hibiscus rosa-sinensis (bunga raya) dalam sistem bioretention melalui kajian tanah dan tumbuhan. Kajian ini dijalankan dalam dua peringkat. Pada Peringkat 1, kajian dilakukan dengan mengubahsuai media bioretention dengan 10% (mengikut isi padu) bahan tambahan dari pelbagai bahan-bahan buangan (kulit kerang, akhbar, kertas bercetak, sabut kelapa, dan remah tayar) dan ditanam dengan Hibiscus rosa-sinensis. Hasilnya, media yang diubahsuai dengan hirisan akhbar (NP) menunjukkan jumlah penyingkiran pepejal terampai (TSS) tertinggi (98.4%), berbanding dengan media bioretention standard (STD, 85.4%), dan menunjukkan peningkatan yang ketara dalam penyingkiran jumlah nitrogen (TN, 80.4%), berbanding dengan STD (57.5%) apabila disiram dengan air larian sebenar. Medium yang diubahsuai dengan hancuran kulit kerang (CS) menunjukkan jumlah penyingkiran fosforus (TP) yang paling tinggi (93.3%), berbanding dengan STD (84.8%), dan media ini juga menunjukkan pertumbuhan pokok yang lebih baik, berbanding dengan media lain. Oleh itu, NP dan CS telah dipilih untuk kajian di Peringkat 2, dan tiga jenis komposisi media (komposit jenis media A, B dan C, CS sebagai lapisan atas dan NP sebagai lapisan bawah, dengan kedalaman yang berbeza) telah direka. Hasilnya, media komposit mencatatkan penyingkiran TSS, TN dan TP sehingga 99.4%, 87.6% dan 96.8%, menandakan bahawa CS dengan ketebalan minimum 300mm dari lapisan atas tanah menggalakkan pertumbuhan pokok dan NP dengan ketebalan minimum 300mm dari lapisan bawah tanah menyediakan zon anaerobik (dibentuk oleh poket mikro daripada akhbar) untuk denitrifikasi. Pengiraan Indeks Kualiti Air (WQI) menunjukkan bahawa media komposit meningkatkan kualiti air dari Kelas V ke Kelas II, dan kekonduksian hidraulik untuk semua jenis media berada dalam julat yang disyorkan. Kajian ke atas pokok menunjukkan bahawa sistem akar yang tebal dan kadar pertumbuhan pesat pokok renek tropika terbukti memberikan sumbangan terhadap penyingkiran TN, dan kandungan tinggi TN dalam daun boleh disingkirkan daripada sistem dengan pencantasan semasa penyelenggaraan. Dua persamaan linear regresi telah diperoleh bagi menggambarkan hubungan antara penyingkiran jisim nitrogen (NMR), pengurangan kepekatan nutrien, kadar pertumbuhan pokok dan penggunaan bahan tambahan. Kesimpulannya, berdasarkan kajian ini, kulit kerang dan akhbar berpotensi menjadi bahan tambahan, dan Hibiscus rosa-sinensis disyorkan untuk meningkatkan sistem bioretention dalam rawatan air larian, terutamanya air larian yang kaya dengan nutrien dari kawasan pembangunan bercampur. ________________________________________________________________________________________________________________________ Nutrient input from urban runoff, especially nitrogen (N) and phosphorus (P), are primary concern for the protection of aquatic ecosystems. This laboratory study investigated the enhanced bioretention system with the objectives to investigate and optimize the performance of additives in bioretention media for nutrient removal, and to elucidate the phytoremediation potential of Hibiscus rosa-sinensis in bioretention system through soil and plant study. The study was conducted in two stages. In stage 1 test, bioretention media was enhanced with 10% (by volume) additives from various waste materials (cockle shell, newspaper, printed paper, coconut husk and tyre crumb) and planted with Hibiscus rosa-sinensis. It was found that the media enhanced with shredded newspaper (NP) performed the best in total suspended solids (TSS) removal (98.4%), as compared to standard bioretention media (STD) (85.4%), and demonstrated a significant improvement in total nitrogen (TN) removal (80.4%), as compared to STD (57.5%), when dosed with actual runoff. Media enhanced with crushed cockle shell (CS) showed the highest total phosphorus (TP) removal (93.3%), as compared to STD (84.8%), and reflected better plant growth among the media. Therefore, NP and CS were shortlisted for stage 2 experiment, and three types of media compositions (composite media type A, B and C, with different depth of CS on top and NP at bottom) were designed. As a result, composite media recorded TSS, TN and TP removal up to 99.4%, 87.6% and 96.8% respectively, which indicated that CS with minimum thickness of 300mm from the top of soil promotes better plant growth and NP with minimum thickness of 300mm from bottom of soil could provide anoxic zone (created by micro pockets formed by newspaper) for denitrification. Water Quality Index (WQI) calculation showed that composite media improved the water quality from Class V to Class II, and the hydraulic conductivity of all types of media fell within recommended range of various bioretention manuals. Study on plant indicated that the thick root system and rapid growth rate of the tropical shrub was proven contributed to TN removal, and high TN content in leaves could be removed from the system by pruning during maintenance. Two linear regression equations were derived to describe the relationship between nitrogen mass removal (NMR), and nutrient concentration reduction, plant growth and use of additives. This study concluded that cockle shell and shredded newspaper can be potential additives and Hibiscus rosa-sinensis is recommended to enhance bioretention system in treating.

    Item Type: Thesis (PhD)
    Additional Information: Full text is available at http://irplus.eng.usm.my:8080/ir_plus/institutionalPublicationPublicView.action?institutionalItemId=2204
    Subjects: T Technology
    T Technology > TC Hydraulic engineering. Ocean engineering > TC401-506 River, lake, and water-supply engineering (General)
    Divisions: Kampus Kejuruteraan (Engineering Campus) > Pusat Penyelidikan Kejuruteraan Sungai dan Saliran Bandar (REDAC) > Thesis
    Depositing User: Mr Mohd Jasnizam Mohd Salleh
    Date Deposited: 26 Jun 2018 12:30
    Last Modified: 26 Jun 2018 12:30
    URI: http://eprints.usm.my/id/eprint/40810

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