A comparison between water exchange and settling tank as a method for suspended solids management in intensive biofloc technology systems: effects on shrimp (Litopenaeus vannamei ) performance, water quality and water use

Abstract

A comparison between water exchange and settling tank as a method for suspended solids management in intensive biofloc technology systems: effects on shrimp (Litopenaeus vannamei) performance, water quality and water use Abstract Biofloc systems rely on microbial processes in the water column to recycle animal waste products, reducing the need for water exchange. These increases biofloc concentration in the water and some form of removal is needed. An experiment was carried out to evaluate two management practices to control biofloc in Litopenaeus vannamei culture. Six tanks (48 m 3 ) were divided into two treatments: water exchange and solid settler. Shrimp were stocked at 164 shrimp m À2 and with 0.67 g of weight. After 61 days, shrimp under solid settler treatment demonstrated mean weight of 12.7 AE 0.5 g with survival of 73.8 AE 1.4%, and those under water exchange had a final weight of 10.1 AE 0.2 g and survival rate of 57.8 AE 11.1%. Total suspended solids did not differ between the treatments: 326.8 AE 24.9 mg L À1 for water exchange and 310.9 AE 25.3 mg L À1 for solid settlers. Settleable solids and productivity/respiration ratio was higher (P < 0.05) in water exchange treatment, indicating differences in physical and biological characteristics of bioflocs. Solids removal method influenced the water use, in which 1150 AE 249 L of water was necessary to produce one kilogram of shrimp using water exchange strategy, and 631 AE 25 L kg À1 with the use of settlers. Our results indicate that continuous operation of settlers can reduce variability in solids characteristics and water quality variables such as ammonia. Both strategies are efficient in controlling biofloc concentrations of the water; however, settlers can reduce water use and improve shrimp production.

TILAPIA CULTIVATED IN A LOW-SALINITY BIOFLOC SYSTEM SUPPLEMENTED WITH <i>Chlorella vulgaris</i> AND DIFFERENTS MOLASSES APPLICATION RATES

“…The high concentrations of SS and TSS can cause discomfort in fish such as the accumulation of organic matter in the gills, which affect oxygen diffusion and also growth (Hargreaves, 2006;Avnimelech, 2012;Arantes et al, 2017). In a study of Litopenaeus vannamei culture in biofloc, Arantes et al (2017) found that the use of a settler chamber promoted improved the zootechnical performance of shrimp, resulting in higher productivity, survival and final weight.…”

Integration of substrate in biofloc based system: Effects on growth performance, water quality and immune responses in black tiger shrimp, Penaeus monodon culture

“…This leads to deterioration of water quality which negatively affects the health and growth of cultured shrimp (Gaona, Almeida, Viau, Poersch, & Wasielesky, ; Ray, Lewis, Browdy, & Leffler, ). To periodically remove excess unutilised floc particles various strategies such as central drainage system (Avnimelech, ) and settling tanks (Arantes, Schveitzer, Magnotti, Lapa, & Vinatea, ; Ray, Dillon, & Lotz, ) have been advised, these demands added facility and expenditure apart from wastage of microbial floc generated by additional carbohydrate application.…”

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“…La remoción de nitrógeno por medio de los tres sistemas señalados son diferentes en términos de la utilización del sustrato, biomasa bacterial generada y subproductos, por lo que en un cultivo intensivo de camarón con cero recambio, los tres sistemas pueden estar presentes y competir por el mismo sustrato. De esta forma, la habilidad para controlar la proporción de carbono a nitrógeno mediante la formulación del alimento balanceado, remoción de sólidos y adición de carbono orgánico determinará la estrategia de manejo para el tipo de sistema utilizado (Arantes et al, 2016).…”

“…The removal of nitrogen through the three appointed systems are different in terms of substrate use, bacterial biomass generated and subproducts, therefore, in an intensive shrimp culture with zero replacement, the three systems can be present and compete with the same substrate. Thus, the ability to control the proportion of carbon to nitrogen by the formulation of balanced feed, solid removal and addition of organic carbon will determine the management strategy for the type of system used (Arantes et al, 2016).…”

“…BFT has been used in intensive production of shrimp since the 90s. BFT enhances the health of shrimp by the stimulation of their (Neal et al, 2010;Baloi et al, 2013), salinidad (Esparza-Leal et al, 2016), alcalinidad (Furtado et al, 2012;Piérri, 2012), consumo de oxígeno disuelto (Vinatea et al, 2010), calidad del agua bajo diferentes concentraciones de biofloc (Ray et al, 2011;Schveitzer et al, 2013a;2013b), métodos de manejo para el control de sólidos suspendidos totales (Arantes et al, 2016), clarificación del agua (eliminación de la turbiedad) (Gaona et al, 2011), calidad nutricional del biofloc , substratos artificiales (Schveitzer et al, 2013b) y sistemas acuícolas integrados (Liu et al, 2014;Brito et al, 2014).…”