Influence of Heavy Metals on the Growth of Chlorella vulgaris

Growth inhibition of chromium (Cr), cadmium (Cd) and lead (Pb) to fresh water microalga Chlorella vulgaris (C. vulgaris) FACHB-8 was examined. These results demonstrated that the concentration level (EC50 value) of three heavy metals (Cr, Cd and Pb) could be utilized as an indicator for evaluating the toxicities of Cr, Cd and Pb for microalga growth. The EC50 values of Cr for C. vulgaris were 0.22, 0.07 and 0.04 mg/L at 24, 48 and 72 h based on Algorithm 2 (%Ir, percent inhibition in average specific growth rate), respectively. The EC50 values of Cd for C. vulgaris were 2.76, 1.08 and 0.93 mg/L at 24, 48 and 72 h based on Algorithm 2, respectively. The EC50 values of Pb for C. vulgaris were 73.21, 65.02 and 48.38 mg/L at 24, 48 and 72 h based on Algorithm 2, respectively. The results laid a good foundation for the application of C. vulgaris in the water quality monitoring.

ANALISIS PENGGUNAAN FERMENTASI PROBIOTIK PADA PAKAN TERHADAP PRODUKTIFITAS UDANG VANAME (Litopenaeus vannamei)

Beberapa tahun terakhir pembudidaya udang Vaname sudah meninggalkan penggunaan antibiotik untuk membantu mengatasi penyakit dalam upaya meningkatkan hasil panen, karena terbukti penggunaan bakteri menjadi semakin meningkatkan resistensi bakteri patogen terhadap antibiotik. Probiotik menjadi solusi terbaik saat ini untuk mendapatkan keberhasilan optimal pada hasil produksi budidaya udang Vaname. Tujuan dari penelitian ini supaya memperoleh pengetahuan konsentrasi terbaik penggunaan probiotik yang diberikan dengan pencampuran pakan dengan berbeda konsentrasi untuk pertumbuhan, sintasan dan FCR udang vaname (Litopenaeus vannamei). Metode yang digunakan pada penelitian ini eksperimental yang terdiri atas 4 perlakuan yaitu A (tanpa penambahan probiotik fermentasi pada pakan), B (penambahan probiotik fermentasi 0,5 liter), C (pakan dengan Probiotik fermentasi 1 liter), dan P3 (pakan dengan Probiotik fermentasi 1,5 liter) pada wadah dengan kepadatan 100 ekor/L. Hasil penelitian menunjukkan rata-rata laju pertumbuhan spesifik udang Vaname berkisar antara 0.16-0,26 %, tingkat kelangsungan hidup berkisar antara 49 – 93 %. In the last few years, vaname shrimp farmers have abandoned the use of antibiotics to help overcoming the disease as an effort to increase crop yields, because it is proven that the use of bacteria has increased the resistance of pathogenic bacteria to antibiotics. Probiotics are the best solution at this time to obtain optimal success in the production of vaname shrimp. The purpose of this study is to obtain the best concentration of probiotic use given by mixing feed with different concentrations for growth, survival and FCR of vaname shrimp (Litopenaeus vannamei). The method used in this experimental study consisted of 4 treatments namely A (without addition of fermented probiotics in feed), B (addition of 0.5-liter fermented probiotics), C (feed with 1-liter fermented probiotics), and P3 (feed with 1.5-liter fermented probiotics) in containers with a density of 100 ind./L. The results showed that the average specific growth rate of vaname shrimp ranged from 0.16 to 0.26% and the survival rate ranged from 49 to 93%.

Growth parameters of common carp Cyprinus carpio cultivated in semi- closed system

Growth parameters of common carp Cyprinus carpio were investigated in 13 plastic tanks (550 cm diameter and 130 cm depth) of semi-closed system at Abu Al- Khaseeb District, Basrah from 27 October to 17 December, 2016. Number of fishes in every tank was 1300 with an average initial weight 101.9 g. Fishes were fed at a ratio of 5% on sinking pelleted food manufactured in Basrah University factory with 25% protein ratio. Results of current study exhibited highest final weight (381.1 g) achieved by fishes reared in tank number 1 and lowest (326.3 g) in tank number 2. Average fish weight increments for 13 tanks were 248.2 g, with highest weight increment (266.5 g) achieved by fishes reared in tanks 6 and 11, while lowest (222.3 g) achieved by fishes reared in tank number 7. Result also appeared average daily growth of 4.87 g/day, with highest (5.22 g/day) achieved by fishes reared in tanks 6 and 11 and lowest (4.36 g/day) achieved by fishes reared in tank number 7. Average specific growth rate for 13 tanks was 2.44 %/day, with highest (3.10 %/day) achieved by fishes reared in tank number 3 and lowest (1.99 %/day) achieved in tank number 1. Average food conversion rate (FCR) for 13 tanks was 2.12, with highest (2.55) achieved by fishes reared in tanks number 1 and lowest (1.74) achieved by fishes reared in tank number 3.

Growth of microalgal biomass on supernatant from biosolid dewatering

The paper reports the results of an experiment to assess the feasibility of including a photobioreactor within the design of a wastewater treatment plant, growing microalgae on the centrate from anaerobic sludge dewatering. The growth of algal biomass would take advantage of the available nitrogen and provide a substrate for biogas production by anaerobic digestion. Tests were carried out by semi-continuously feeding a photobioreactor with a centrate–effluent blend and by increasing the fraction of centrate. The experimental results show that the centrate does not induce any toxicity and, on the contrary, can be well utilized by microalgae, whose average specific growth rate (μ), on centrate as such, was between 0.04 and 0.06 d−1. The maximum biomass concentration in the photobioreactor effluent was 1.6 gSS/L at 10 days HRT (hydraulic retention time). Methane production tests led to biochemical methane production values of 335 ± 39, and 284 ± 68 mL 0°C, 1 atm CH4/g VS for the two tested samples, in agreement with literature values. Settling tests show that the settling capacity of microalgae, although satisfactory, could be effectively improved after mixing with activated sludge, confirming the potential to use the existing primary settler for microalgae thickening in order to feed microalgae for anaerobic digestion with primary/secondary sludge.