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Biofloc technology (BFT) is an alternative to the tilapia waste management system in the nutrient film technique (NFT)-aquaponics (AP) system. This gadget works by utilizing microorganisms that can transform natural waste into flocks of microorganisms that may then be consumed as natural feed by fish, hence enhancing feed performance. The water from the FT (Fish Tank) is first pumped to the MFT (Mechanical Filter Tank), then to the BT (Biofilter Tank), ST (storage Tank), HS (Hydroponics Subsystem), and lastly back to the FT. The study's findings show that water quality is good, with DO (5.9800-6.7000 mg/L), BOD (2.4422-3.5798 mg/L), COD (17.7916-20.8982 mg/L), pH (7.20-8.63), and temperature (26.9-29.4°C) all being within acceptable ranges. After the study, 96 percent of the fish survived. This suggests that BFT can reduce the mortality rate of cultured fish, and plants no longer exhibit nutrient deficiency symptoms such as stunted growth and necrotic areas on leaves.

To meet the consumption needs of fish and vegetables by utilizing a narrow urban land it can be used an aquaponic system. The aquaponic system is an integration of fish farming with hydroponic cultivation that utilizes the remains of feed and fish waste into nutrients for plants with the help of nitrifying bacteria. In this study used tilapia (Oreochromis niloticus) and Pakcoy (Brassica rapa L). Determination of ammonia, nitrite, and nitrate concentration aims to find the ammonia change to nitrite and nitrate in fish ponds, biofilter, and hydroponic sequences, and their absorption by plants. The ammonia concentration at three sampling points (3.231-8.989) mg/L and has exceeded the threshold of 0.02 mg/L, while for ammonia concentrations in each sample of pakcoy plant (558.563-2,001.659)mg/Kg. The concentration of nitrite (0.008-0.760)mg/L and has exceeded the standard quality threshold of 0.06 mg/L, except in the 0 day water sample sample 0.009 mg/ L and the water sample after the biofilter 0.008 mg/L, the concentration of nitrite pakcoy plant (3.764-12.321)mg/Kg. Nitrate concentration in water sample (1.046-2.275)mg/L, and still below the standard threshold of freshwater aquaculture (20-30)mg/L, nitrate concentration in pakcoy plant (4,890.09-12,864.7)mg/Kg. Ammonia and nitrite concentrations have exceeded the threshold, while nitrate concentrations are still below the threshold.

ABSTRACT The research about determination of Cu(II) by adsorptive stripping voltammetry (AdSV) was conducted. AdSV method was applied to the determination of copper in ultra trace concentration. The parameters of ligand, accumulation potential, accumulation time, pH and ligand concentration was studied. Calcon was found as complexing agent that give the highest peak current. The optimum condition are accumulation potential -0,7 V, accumulation time 60 s, pH 10, and calcon concentration 0.12 mM. The relative standar deviation (n=8) at 10 µg/L standard concentration were obtained 4,27 %. This method was applied to determination of Cu(II) in sample from Batang Air Dingin, Lubuk Minturun and Muara Padang. The sample concentration were 4,778 µg/L and 5,189 µg/L for Batang Air Dingin and Muara Padang, respectively. The recovery of this method was studied for sample from Muara Padang and 98,31 % was obtained. Key words : Adsorptive, Stripping, Voltammetry, Calcon and Copper

ABSTRACT Study of optimation cadmium(II) by adsorptive stripping voltammetry has been done. The aim of this study to get optimum conditions for determination of Cd(II). Parameters were done : potential accumulation, time accumulation, pH, supporting electrolite concentration and optimum of complex concentration. In this case, the optimum conditions were reached in potential accumulation -0.7 V, time accumulation 60 second, pH 7.0, NH4Cl 0.12 M, calcon concentration 0.12 mM. In the optimum condition was obtained with the relative standard deviation was 4.61% for eight replicates, measurements of 0.01 ppm. The method was applied to the direct determination of Cd(II) in water around Batang Air Dingin Lubuk Minturun and Muara Padang. Concentration Cd(II) in sample was equal to 7.359 μg/L and 3.659 μg/L with recovery of 99.04%. Keywords: cadmiun, adsorptive, stripping, voltammetry

ABSTRACT Study of optimation chromium (VI) in sea water by adsorptive stripping voltammetry has been done. The aim of this method to get optimum conditions for determination of Cr(VI). Adsorptive stripping voltammetry (AdSV) has been used for the ultra trace determination of chromium using 2,2’- bipyridin as ligand. Parameters were done, like accumulation time, concentration of ligand, pH, accumulation potential, electrolyte concentration and catalyst concentration. In this case, the optimum conditions were reached in accumulation time 80 second, pH 5.0, concentration of 2,2’- bipyridin 10 μM, accumulation potential -0,6 Volt and electrolyte concentration (NH4Cl) 0,1 M. In the optimum conditions, a linear calibration graph was obtained with correlation coefficient of 0.9971, the relative standard deviation was 15.06 % for eight replicates (n = 8) measurements of 10 μg/L of Cr(VI). The detection limit method was 0.1692 μg/L. The method was applied to the direct determination of Cr(VI) in sea water around Muara Padang water. Concentration Cr(VI) in sample was equal to 0.9684 μg/L with recovery of 90.23 %. Keywords : optimation, chromium, adsorptive, stripping, voltammetry