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

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

Combined Field Integral Equation Based Theory of Characteristic Mode

Conventional electric field integral equation based theory is susceptible to the spurious internal resonance problem when the characteristic modes of closed perfectly conducting objects are computed iteratively. In this paper, we present a combined field integral equation based theory to remove the difficulty of internal resonances in characteristic mode analysis. The electric and magnetic field integral operators are shown to share a common set of non-trivial characteristic pairs (values and modes), leading to a generalized eigenvalue problem which is immune to the internal resonance corruption. Numerical results are presented to validate the proposed formulation. This work may offer efficient solutions to characteristic mode analysis which involves electrically large closed surfaces

Computers in the Examining Room: Evaluating the Social Impact on Practice Patterns

This paper uses social network analysis to examine the impacts on practice patterns of the introduction of CompuHx, an Interactive Health Appraisal System (IHAPS), used in the examining roomat Kaiser Permanente\u27s San Diego Department of Preventive Medicine. The system is used to record patient information, assist in diagnosis, and provide a summary of findings. Twenty-two physician assistants and nurse practitioners responded to detailed surveys after the system was implemented. Findings indicate practitioners who used the computer system interacted more frequently with the other physician assistants and nurse practitioners, with physicians, and with individuals in other departments. Overall,the study points to the value of using network analysis to investigate the impact of computer technology on individuals\u27 attitudes and behaviors

Spatial inequalities in Malaysia’s non-revenue water rates issues, challenges and management strategies

In Malaysia, high non-revenue water (NRW) rate is amongst the country’s top water issues. NRW rates of all states in the country vary greatly, with the rates ranging from 18.2 to 62.4 per cent. This huge spatial variation is due to variations in management efficiency of the water operator, amount of funding for NRW reduction programme and level of public awareness. This paper aims to examine the effect of the spatial inequality on NRW management in Malaysia’s states by comparing NRW rates between states with different area sizes. The study is mainly based on literature review and secondary data. The results show that states with smaller surface areas recorded lower NRW rates but the smallest state was found to record the highest NRW rate. Factors such as service’s coverage area, population density, water supply network density, dispersal of the city area, and location of the water users, and type of water users also have significant impacts on NRW management. For example, high water supply network density, poor water resources availability and high demand in Penang have forced the state’s water operator to increase its efficiency in NRW management. In contrast, low water demand, low population density, and less commercial area in Perlis are found to be the reasons of high NRW rate in the state. In conclusion, spatial factors can impact NRW as smaller states can better manage NRW due to the smaller water service areas covered. However, states cannot use size of service area and spatial variations as excuses for high NRW as the study found that adequate funding, proper planning, effective management, efficient service, and proactive strategies of water operator are more important factors that can have significant impacts on the NRW rates