Optimization of organics to nutrients (COD:N:P) ratio for aerobic granular sludge treating high-strength organic wastewater.

The present study attempted to optimize the nutrients required for biological growth and biomass synthesis in the treatment of high-strength organics wastewater using aerobic granular sludge (AGS). Three identical sequencing batch reactors (SBRs) were used to cultivate aerobic granules at COD concentration of ~5000 mg/L at COD:N:P ratios of 100:2.8:0.4, 100:4.4:0.5, and 100:5:0.7. Results indicated that the amount of nutrients needed for biomass growth does not follow the conventional organics to nutrients ratio (COD:N:P) of 100:5:1 when dealing with high-strength organics wastewater. The highest removal efficiency was achieved at COD:N:P ratio of 100:2.8:0.4, where COD, TN, and P removal was 98.8 ±â€¯0.3%, 100.0 ±â€¯0.0%, and 99.3 ±â€¯1.0%, respectively. Moreover, the presence of high amounts of organics led to the dominance of the fast-growing heterotrophs in all SBRs, with the genus Thauera identified as the most abundant genera (23-40%), while autotrophic nitrifiers disappeared. The observed biomass yield at COD:N ratio of 100:2.8 suggested that heterotrophic nitrification may have occurred, while at COD:N ratios of 100:4.4 and 100:5, all the nitrogen was used for biomass synthesis. Moreover, at COD:N ratio of 100:5, almost 1/5 of the organics were utilized by the biomass cells to produce EPS as defensive action against the effects of free ammonia. Batch optimization experiments showed that the fastest rate of removal occurred at COD:N:P ratio of 100:1.1:0.4. After 4 h, the COD, TN, and P removal efficiencies were 95%, 99%, and 96%, achieving overall removal efficiencies of 98%, 100%, and 97% respectively, at HRT of 8 h. The bacterial behavior in consuming the organics was altered under nutrient-deficient conditions, where faster degradation rates were observed as the amounts of nutrients decreased, with higher relative abundance of heterotrophs and diazotrophic bacterial populations.

Niveles de calcio para codornices en postura / Calcium levels in layers quail / Níveis de cálcio para codornas em postura

Resumen Con el objetivo de evaluar el efecto de los niveles de calcio en la dieta sobre los parámetros productivos de codornices, fue realizado este trabajo en la Unidad de codornices de la Universidad de los Llanos, con 240 codornices de 75 días de edad y 151,9 ± 8,5 g de peso, durante 26 semanas, distribuidas en un diseño experimental completamente al azar, con cuatro tratamientos, seis repeticiones y 10 aves por repetición, para un total de 24 unidades experimentales. Las aves fueron alojadas en jaulas de alambre, en módulos de cinco pisos con tres divisiones por piso, dotadas de comederos lineales y bebederos automáticos. Los tratamientos fueron elaborados con inclusiones de carbonato de calcio (4,9; 5,28; 5,67 y 6,06) para constituir dietas con niveles de 2,30; 2,45; 2,60 y 2,75% de calcio. Los niveles de calcio influyeron (p<0,05) la producción de huevos (80,19; 81,76; 71,67 y 79,15%), el consumo diario de ración (24,26; 24,76; 24,50 y 24,53 g/ave/ día), la conversión alimenticia por docenas de huevo (0,333; 0,340; 0,389 y 0,347) y la conversión por masa de huevo (2,77, 2,84, 3,24 y 2,89). Sobre el peso del huevo (10,91; 10,69; 10,55 y 10,74 g) no hubo efectos (P>0,05). En conclusión, el nivel de calcio que permite obtener mejores parámetros productivos se estima en 2,48%.

Abstract In order to evaluate the effect of calcium levels in the diet on performance of quails it was performed this work in quail Unit of the University of the Llanos, with 240 quails 75 days old and 151.9 ± 8.5 g weight for 26 weeks, distributed in a completely randomized experimental design, with four treatments, six replications and 10 birds per repetition, for a total of 24 experimental units. The birds were housed in wire cages, five-storey modules with three divisions per floor, equipped with linear feeders and automatic drinkers. Treatments were made by inclusions of limestone (4.9; 5.28; 5.67 and 6.06) for diets 2.30; 2.45; 2.60 and 2.75% calcium. Calcium levels influenced egg production (80.19, 81.76, 71.67 and 79.15%), daily feed intake (24.26; 24.76; 24.50 and 24.53 g / bird / day), feed conversion per dozen eggs (0.333, 0.340, 0.389 and 0.347) and mass conversion Egg (2.77, 2.84, 3.24 and 2.89) on egg weight (10.91; 10.69; 10.55 and 10.74 g) there was no effect (P> 0 05). In conclusion, the level of calcium that leads to better production parameters is 2.48%.

Resumo Para avaliar o efeito dos níveis de cálcio na dieta sobre os parâmetros produtivos de codornas, este trabalho foi realizado na Unidade de Codornas da Universidade dos Llanos, com 240 codornas de 75 dias de idade e 151,9 ± 8,5 g de peso, durante 26 semanas, distribuídos em delineamento experimental inteiramente casualizado, com quatro tratamentos, seis repetições e 10 aves por repetição, para um total de 24 unidades experimentais. As aves foram alojadas em gaiolas de arame, em módulos de cinco andares com três divisões por andar, equipadas com comedouros lineares e bebedouros automáticos. Os tratamentos foram elaborados com inclusões de carbonato de cálcio (4.9, 5.28, 5.67 e 6.06) para formar dietas com níveis de 2,30; 2,45; 2,60 e 2,75% de cálcio. Os níveis de cálcio influenciaram (p <0,05) a produção de ovos (80,19, 81,76, 71,67 e 79,15%), consumo diário de ração (24,26, 24,76, 24,50 e 24,53 g / ave / dia), a conversão alimentar por dúzia de ovos (0,333, 0,340, 0,389 e 0,347) e a conversão por massa de ovo (2,77, 2,84, 3,24 e 2,89). No peso do ovo (10,91, 10,69, 10,55 e 10,74 g), não houve efeitos (P> 0,05). Em conclusão, o nível de cálcio que permite obter melhores parâmetros produtivos é estimado em 2,48%.