Tofu production is a domestic industry, that most of it has no appropriate wastewater treatment facilities. Wastewater of tofu contains high organic matter which can decrease the water quality. This study aimed to analyze capability of Vetiveria zizanioides, L and zeliac in treating tofu wastewater industry. Zeliac is a new adsorbent, which consists of zeolite, activated carbon, limestone, rice husk ash and cement. Response surface methodology was applied to analyze the data, using central composite design with two factors, i.e., time (3, 9, and 15 days) and waste concentration (20, 40, and 60%). The optimum treatment occurred at the time of 15 days and 38.41% of tofu wastewater concentration decreasing up to 76% of COD, 71.78% of BOD, and 75.28% of TSS.

This study was conducted to compare water quality and channel catfish production in earthen ponds located in two dissimilar physiographic regions of the southeastern United States and supplied with water of disparate quality. Ponds at Auburn, Alabama are on acidic Piedmont soils and filled with poorly mineralized runoff water; ponds at Stoneville, Mississippi are on slightly alkaline alluvial clays and filled with groundwater of high total alkalinity and hardness. Channel catfish were stocked at 8,750 fish/ha, fed daily, and provided nightly aeration in 0.04‐ha ponds at both sites. Ponds were managed as similarly as possible. Minimum daily water temperatures and pH were higher at Stoneville than at Auburn, and there were greater concentrations of suspended clay turbidity, dissolved inorganic phosphorus, total ammonia‐nitrogen, and nitrite‐nitrogen at Auburn than at Stoneville. The taxonomic composition of the phytoplankton community was broadly different between the two sites. Taste tests revealed off‐flavor in fish at both sites, but there were no significant differences (P > 0.05) in flavor scores between sites. The quality of flavor was somewhat different between sites, and these differences in quality were thought to result from observed differences in the taxonomic composition of phytoplankton communities. All differences in water quality seemed to be directly or indirectly related to the dissimilarity in the quality of the water supply and soils at the two locations. Although some water quality variables differed between sites and changed over time at both sites, environmental conditions never deteriorated enough at either site to cause serious stress or mortality in fish. There were no significant differences (P > 0.05) in average net fish production, survival, weight of individual fish at harvest, or feed conversion ratios. Average net fish production and feed conversion ratios, respectively, were 4,905 kg/ha and 1.27 at Auburn and 5,286 kg/ha and 1.27 at Stoneville. The results of this study demonstrate the need for site‐specific investigations when conducting certain types of aquaculture research.

ABSTRAK Teknologi bioflok merupakan salah satu alternatif untuk mengatasi masalah kualitas air lingkungan budidaya yang diadaptasi dari teknik pengelolaan limbah secara konvensional. Tujuan dari penelitian ini adalah mengkaji pemeliharaan benih ikan lele dengan penerapan bioflok dari beberapa produk konsorsium, diantaranya bakteri Bacillus megaterium (BM), Supernit (SP), Depok 165 (DP165), Kayajaga (KJ) dengan membandingkan pemeliharaan tanpa teknologi bioflok untuk perbaikan kualitas air. Hasil penelitian dan uji statistik menunjukkan bahwa, konsentrasi TAN terendah oleh probiotik KJ sebesar 2,56 mg L-1 sedangkan kontrol sebesar 5,47 mg L-1 dan konsorsium bakteri memberikan pengaruh terhadap TAN (p<0,05). Konsentrasi amonia terendah oleh probiotik KJ sebesar 0,0001853 mg L-1 sedangkan kontrol sebesar 0,0003973 mg L-1 , dan konsorsium bakteri tidak memberikan pengaruh terhadap amonia (p>0,05). Konsentrasi nitrit terendah oleh probiotik BM sebesar 0,065 mg L-1 sedangkan kontrol sebesar 0,124 mg L-1 , dan konsorsium bakteri memberikan pengaruh terhadap nitrit (p<0,05). Konsentrasi nitrat terendah oleh probiotik BM sebesar 1,203 mg L-1 sedangkan kontrol sebesar 3,437 mg L-1 , dan konsorsium bakteri memberikan pengaruh terhadap nitrat (p<0,05). Konsorsium bakteri memberikan pengaruh terhadap COD (p<0,005) akan tetapi seluruh perlakuan konsorsium memiliki nilai konsentrasi lebih tinggi yang berkisar antara 430475 mg L-1 dibandingkan kontrol. Dari sini ditarik kesimpulan bahwa penerapan bioflok dapat memperbaiki kualitas air, dimana hal ini terlihat dari penurunan nilai konsentrasi parameter TAN, amonia, nitrit, dan nitrat.

ABSTRAKDanau Toba merupakan danau terbesar di Indonesia yang terletak di Provinsi Sumatera Utara. Danau Toba banyak dimanfaatkan oleh masyarakat untuk kegiatan budi daya ikan di keramba jaring apung (KJA), pertanian, pariwisata, dan pemukiman penduduk. Aktivitas-aktivitas tersebut akan memberikan masukan berupa bahan organik dan anorganik yang akan memengaruhi kualitas air dan dapat menyebabkan terjadinya eutrofikasi. Beberapa indikator eutrofikasi adalah terjadi peningkatan biomassa fitoplankton dan perubahan struktur komunitas fitoplankton. Tujuan dari penelitian ini adalah untuk mengkaji struktur komunitas fitoplankton di Danau Toba. Penelitian ini dilakukan pada tanggal 2024 Oktober 2014 di 23 stasiun di perairan sekitar Pulau Samosir, Danau Toba. Hasil penelitian menunjukkan bahwa kelimpahan fitoplankton berkisar antara 216-68.319.716 sel/m 3 . Komposisi fitoplankton terdiri dari 35 genus dari empat kelas, yaitu Cyanophyceae, Chlorophyceae, Bacillariophyceae, dan Dinophyceae. Cyanophyceae merupakan kelas fitoplankton yang dominan berdasarkan komposisi kelimpahannya (>40%). Struktur komunitas fitoplankton di Danau Toba didominasi oleh Anabaena.Kata kunci: danau toba, fitoplankton, struktur komunitas ABSTRACT Lake Toba is the largest lake in Indonesia, located in the Province of North Sumatra. Lake Toba is used to aquaculture, agricultural, tourism, and residential areas. These activities will produce organic and anorganic matter that can affect water quality and can cause eutrophication. Some indicators of eutrophication are an increase in phytoplankton biomass and changes in phytoplankton community structure. The aim of this study was to describe the phytoplankton community structure in Lake Toba. This study was conducted on 2024 October 2014 at 23 stations around the Samosir Island, Lake Toba. The results showed that the phytoplankton abundance ranged 216-68.319.716 cells/m 3 . The phytoplankton composition consists of 35 genera from four classes: Cyanophyceae, Chlorophyceae, Bacillariophyceae, and Dinophyceae. Cyanophyceae is a dominant phytoplankton groups based on the composition of abundance (>40%). Structure of phytoplankton communities in Lake Toba dominated by Anabaena.

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