Judul: The Design of Simple Water Reclaim System for Domestic Wastewater (Greywater)
Abstrak: Pertumbuhan populasi, perkembangan industri dan agrikultur, urbanisasi serta faktor kontaminasi dan kekeringan sumber, menjadi tantangan dalam pemenuhan kebutuhan air. Indonesia adalah negara kaya akan sumber air namun seiring dengan perkembangan pembangunan dan perubahan iklim, beberapa kota besar dilaporkan sedang mengalami krisis air dan penurunan kualitas air tanah. Cara kontruktif yang dapat dilakukan masyarakat dalam mendukung perbaikan kualitas sumber air salah satunya adalah usaha mengurangi dan mendaur ulang air limbah. Laporan statistik lingkungan hidup Indonesia tahun 2020 menyatakan lebih dari separuh limbah rumah tangga yang berasal dari mandi, mencuci, kegiatan dapur dialirkan ke selokan atau sungai. Perancangan sistem daur ulang air limbah rumah tangga (greywater) untuk penggunaan kembali dalam ruang lingkup pencucian kendaraan menggunakan tiga tahap secara berurutan yaitu koagulasi menggunakan koagulan alum, filtrasi dengan menggunakan metode multi media filter, dan disinfeksi menggunakan lampu ultraviolet. Pengujian paramer pH, oksigen terlarut, padatan terlarut, padatan tersuspensi dan kadar surfaktan akan dilakukan untuk menentukan kualitas air dengan standar baku yang sesuai dengan tujuan aplikasi air daur ulang. Kata kunci: air, daur ulang air, air limbah, greywater, filtrasi, koagulasi, disinfeksi, ultraviolet., Population growth, industrial and agricultural development, urbanization, and factors of contamination and sources' dryness are challenges in meeting water needs. Indonesia is a country with a lot of water resources. However, in population growth and climate change, several big cities are reportedly experiencing a water crisis and decreasing groundwater quality. One of the constructive ways that the community can support improving the quality of water sources is to reduce and recycle wastewater. The 2020 Indonesian Environmental Statistics report that more than half of household waste from bathing, washing, and kitchen activities goes into sewers, ditches, or rivers. The design of a household wastewater (greywater) reclaim system for application in the scope of vehicle washing uses three sequential stages: coagulation using alum coagulant, filtration using the multi-media filter method, and disinfection using an ultraviolet lamp. Tests for parameters of pH, dissolved oxygen, dissolved solids, suspended solids, and surfactant levels will be carried out to determine the quality of water with standards that are suitable for reclaimed water applications. Keywords: water, water reclaim, wastewater, greywater, filtration, coagulation, disinfection, ultraviolet.
Keyword: water, water reclaim, wastewater, greywater, filtration, coagulation, disinfection, ultraviolet

Judul: DESIGN OF ECO-DRAINAGE IN CONTROLLING DESTRUCTIVE POWER OF RUNOFF, ENVIRONMENTAL POLLUTION, AND INCREASING STORAGE CAPACITY
Abstrak: Sebagian besar permukiman di Indonesia saat ini masih menggunakan sistem drainase konvensional yang mengalirkan air limpasan secepatnya menuju badan air terdekat. Seharusnya air limpasan dapat ditampung dan dimanfaatkan kembali oleh masyarakat sekitar dengan menerapkan sistem eco-drainage. Penelitian ini bertujuan merancang eco-drainage dalam mengendalikan daya rusak air, pencemaran lingkungan, dan peningkatan kapasitas simpan air. Hasil perhitungan debit limpasan dengan metode rasional pada Komplek Anggrek 2 sebesar 1,53 m3/detik. Nilai tersebut melebihi kapasitas saluran terbangun yaitu hanya sebesar 1,04 m3/detik, sehingga diperlukan penambahan saluran baru pada ruas 38-43, 43-40, dan 44-40 yang berfungsi sekaligus untuk mengalirkan air menuju embung. Upaya peningkatan kapasitas simpan air dalam rancangan eco-drainage di lokasi kajian yaitu berupa rancangan embung kecil dengan dimensi panjang 50 m, lebar 15 m, dan kedalaman maksimum 2,5 m sehingga memiliki kapasitas maksimum 1490 m3. Hasil pengujian kualitas air drainase terdapat parameter TSS dan COD yang masih melebihi baku mutu kelas air tiga, sehingga diperlukan unit pengolahan sederhana berupa biofilter dengan media bioball. Total biaya yang diperlukan dalam tindakan konstruksi rancangan eco-drainage yaitu sebesar Rp 722.061.000., Most settlements in Indonesia today still use conventional drainage systems that flow sewage as quickly as possible to the nearest river. The sewage should be able to be stored and reused by the surrounding communities by implementing eco-drainage systems. The research aims to design eco-drainage to control destructive power of runoff, environmental pollution, and increased water storage capacity. The result of the calculation of the discharge by the rational method on Anggrek Complex 2 is 1.53 m3/second. The value exceeds the capacity of the existing channel, which is only 1.04 m3/s, so it is necessary to add new channels on roads 38-43, 43-40, and 44-40 that serve simultaneously to flow water to the pond. The attempt to increase the water storage capacity in the eco-drainage project at the study site is a small pond project with a length of 50 m, a width of 15 m, and a maximum depth of 2.5 m to have a maximum capacity of 1490 m3. The drainage water quality test results have TSS and COD parameters that still exceed the water grade three quality standards, so it requires a simple processing unit of a biofilter with a bioball medium. The total cost required for the construction of the eco-drainage project is Rs 722.061.000.
Keyword: eco-drainage, reservoir, runoff

Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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