Optimasi Penghilangan Nitrogen Air Buangan Tambak Udang Menggunakan Aerasi Nanobubble dan Komposit Multi-Karbon Berbasis Besi

Abstract

Peningkatan intensifikasi budidaya udang vaname (Litopenaeus vannamei) menghasilkan air buangan dengan kandungan nitrogen yang tinggi, terutama total ammonia nitrogen (TAN), nitrit, nitrat, dan total nitrogen (TN), yang berpotensi menyebabkan eutrofikasi apabila dibuang tanpa pengolahan yang memadai. Penghilangan nitrogen secara biologis memerlukan oksigen terlarut yang memadai untuk mendukung proses nitrifikasi, sedangkan denitrifikasi dapat dibatasi oleh ketersediaan sumber karbon dan donor elektron. Penelitian ini bertujuan mengevaluasi efektivitas kombinasi aerasi nanobubble dan iron-based multi-carbon source composites (IMCSC) dalam meningkatkan penghilangan nitrogen dan memperbaiki kualitas air buangan tambak udang. Penelitian menggunakan air buangan tambak udang vaname dari tambak KD Sutoyo, Pemalang, Jawa Tengah, dengan padat tebar 130 ekor/m² dan day of culture (DOC) 57 hari. Penelitian menggunakan rancangan acak lengkap dengan lima perlakuan, yaitu kontrol (C), aerator konvensional (A), nanobubble (NB), IMCSC+aerator (IMCSC+A), dan IMCSC+nanobubble (IMCSC+NB), dengan tiga ulangan selama 50 hari. IMCSC disusun menggunakan polyvinyl alcohol (PVA), natrium alginat, polycaprolactone (PCL), karbon aktif, dan besi valensi nol berukuran mikro. IMCSC ditambahkan dengan dosis 100 g per wadah, sedangkan aerator konvensional dan nanobubble masing-masing dioperasikan selama 12 dan 2 jam/hari. Parameter yang diamati meliputi TAN, nitrit, nitrat, TN, fosfat, BOD, pH, DO, ORP, salinitas, suhu, total bakteri, dan komunitas fitoplankton. Karakteristik nanobubble dianalisis menggunakan particle size analyzer (PSA), sedangkan perubahan senyawa organik dianalisis menggunakan spektrofotometer UV–Vis. Hasil penelitian menunjukkan bahwa perlakuan aerasi dan IMCSC meningkatkan penghilangan nitrogen dibandingkan kontrol. Efisiensi penghilangan TN tertinggi diperoleh pada IMCSC+A sebesar 85,90%, diikuti NB sebesar 84,62%, IMCSC+NB sebesar 84,57%, dan A sebesar 75,55%, sedangkan kontrol sebesar 42,31%. Perlakuan berbasis nanobubble menghasilkan kondisi DO dan ORP yang lebih tinggi dibandingkan kontrol dan aerasi konvensional. Karakterisasi nanobubble menunjukkan ukuran gelembung dominan 200–300 nm dengan zeta potensial sebesar -32,55 mV. Perlakuan juga menurunkan konsentrasi BOD dan fosfat, sedangkan IMCSC+NB menghasilkan kejernihan air terbaik berdasarkan penurunan absorbansi UV–Vis. Evaluasi akhir berdasarkan Peraturan Menteri Lingkungan Hidup dan Kehutanan Republik Indonesia Nomor 1 Tahun 2025 menunjukkan bahwa parameter pH, BOD, PO4 total, dan NH3 total pada perlakuan aerasi berada dalam batas baku mutu yang ditetapkan. Analisis ekonomi menunjukkan bahwa biaya total IMCSC+NB sebesar Rp39.450, lebih rendah dibandingkan IMCSC+A sebesar Rp111.700, dengan efisiensi penghilangan TN sebesar 84,57%. Secara keseluruhan, IMCSC+NB menunjukkan potensi sebagai teknologi pengolahan air buangan tambak udang yang efektif dan ekonomis karena mampu meningkatkan penghilangan nitrogen, memperbaiki kualitas air, dan memiliki biaya operasional lebih rendah dibandingkan kombinasi IMCSC dengan aerasi konvensional.

Kata kunci: air buangan, IMCSC, nanobubble, nitrogen, pengolahan air buangan

The increasing intensification of vannamei shrimp (Litopenaeus vannamei) farming generates wastewater containing high concentrations of nitrogen, particularly total ammonia nitrogen (TAN), nitrite, nitrate, and total nitrogen (TN), which may contribute to eutrophication if discharged without adequate treatment. Biological nitrogen removal requires sufficient dissolved oxygen to support nitrification, whereas denitrification can be limited by the availability of carbon sources and electron donors. This study aimed to evaluate the effectiveness of combining nanobubble aeration and iron-based multi-carbon source composites (IMCSC) to enhance nitrogen removal and improve shrimp aquaculture wastewater quality. Wastewater was collected from a vannamei shrimp farm at KD Sutoyo, Pemalang, Central Java, Indonesia, with a stocking density of 130 shrimp/m² and a day of culture (DOC) of 57 days. A completely randomized design was applied with five treatments: control (C), conventional aeration (A), nanobubble (NB), IMCSC + conventional aeration (IMCSC+A), and IMCSC + nanobubble (IMCSC+NB), with three replicates over a 50-day experimental period. IMCSC was composed of polyvinyl alcohol (PVA), sodium alginate, polycaprolactone (PCL), activated carbon, and micro-sized zero-valent iron. IMCSC was added at a dose of 100 g per experimental container, while conventional aeration and nanobubble were operated for 12 and 2 h/day, respectively. The observed parameters included TAN, nitrite, nitrate, TN, phosphate, BOD, pH, DO, ORP, salinity, temperature, total bacteria, and phytoplankton communities. Nanobubble characteristics were analyzed using a particle size analyzer (PSA), while changes in organic compounds were analyzed using UV–Vis spectrophotometry. The results showed that aeration and IMCSC treatments enhanced nitrogen removal compared with the control. The highest TN removal efficiency was achieved by IMCSC+A (85.90%), followed by NB (84.62%), IMCSC+NB (84.57%), and A (75.55%), whereas the control achieved 42.31%. Nanobubble-based treatments produced higher DO and ORP conditions than the control and conventional aeration. Nanobubble characterization showed a dominant bubble size range of 200–300 nm with a zeta potential of -32.55 mV. The treatments also reduced BOD and phosphate concentrations, while IMCSC+NB produced the highest water clarity based on the reduction in UV–Vis absorbance. Final water quality evaluation based on Regulation of the Minister of Environment and Forestry of the Republic of Indonesia Number 1 of 2025 indicated that pH, BOD, total PO4, and total NH3 in the aeration treatments were within the specified wastewater quality standards. Economic analysis showed that the total cost of IMCSC+NB was IDR 39,450, substantially lower than that of IMCSC+A at IDR 111,700, while achieving a TN removal efficiency of 84.57%. Overall, IMCSC+NB demonstrated potential as an effective and economical wastewater treatment technology for shrimp aquaculture by enhancing nitrogen removal, improving water quality, and reducing operational costs compared with the combination of IMCSC and conventional aeration.

Keywords: wastewater, IMCSC, nanobubble, nitrogen, wastewater treatment