Microbial dynamics during composting of filter cake reactivated with chicken manure

 

Dinámica microbiana en el compostaje de cachaza reactivada con gallinaza

 

Lourdes Alejandra Romero-Yam¹; Juan José Almaraz-Suárez¹; Joel Velasco-Velasco²*; Arturo Galvis-Spinola¹; Francisco Gavi-Reyes³

 

¹ Programa de Edafología. Colegio de Postgraduados. Campus Montecillo. Carretera México-Texcoco km 36.5, Montecillo, Estado de México. C.P. 56230, MÉXICO.

² Colegio de Postgraduados. Campus Córdoba. Carretera Federal Córdoba - Veracruz km 348, Congregación Manuel León, municipio de Amatlán de los Reyes. C.P. 94946, MÉXICO. Correo-e: joel42ts@colpos.mx, tel.: (01) 271 716 6000 (*Autor para correspondencia).

³ Programa de Hidrociencias. Colegio de Postgraduados. Campus Montecillo. Carretera México-Texcoco km 36.5, Montecillo, Estado de México. C.P. 56230, MÉXICO.

 

Received: September 17, 2013.
Accepted: February 19, 2015.

 

Abstract

Microbial dynamics, mineral and total nitrogen content were studied during the composting process of filter cake reactivated with chicken manure. Four substrates with different proportions of filter cake:chicken manure (10:0, 9:1, 7:3 and 5:5 v/v) were tested using 68 liters containers for 87 days. Temperature, total populations of bacteria, fungi, ligninolytic microorganisms, CO₂ evolution, total nitrogen, ammonium and nitrate content were the evaluated variables. The addition of chicken manure to stored filter cake increased the populations of bacteria, fungi and ligninolytic microorganisms, showing microbial populations of 9.9, 5.5 and 6.4 log units (ULog), respectively. Substrate 5:5 v/v showed a decrease in NH⁺₄-N (from 947 to 268 mg∙kg^-1) and an increase in NO^-₃-N (from 2.7 to 483 mg-∙kg¹) and in total nitrogen (3.4 to 4.7 %). This proportion of chicken manure and filter cake was better because it was biologically stable (compost) and had the highest content of total nitrogen.

Keywords: Microbial ecology, lignocellulose, biotransformation of filter cake, compost.

 

Resumen

Se estudió la dinámica microbiana, así como el contenido de nitrógeno mineral y total durante el proceso de compostaje de cachaza reactivada con gallinaza. Se establecieron cuatro sustratos con diferentes proporciones de cachaza:gallinaza (10:0, 9:1, 7:3 y 5:5 v/v), en contenedores de 68 litros durante 87 días. Las variables evaluadas fueron: temperatura, poblaciones de bacterias, hongos, microorganismos ligninolíticos, evolución de CO₂, nitrógeno total, contenido de amonio y nitratos. La adición de gallinaza a la cachaza almacenada, incrementó las poblaciones de bacterias, hongos y microorganismos ligninolíticos, mostrando poblaciones de 9.9, 5.5 y 6.4 unidades logarítmicas (ULog), respectivamente. El sustrato 5:5 v/v presentó disminución en NH⁺₄-N (de 947 a 268 mg∙kg^-1), aumento en NO^-₃-N (de 2.7 a 483 mg∙kg^-1) y en nitrógeno total (3.4 a 4.7 %). Esta proporción de gallinaza y cachaza resultó mejor, ya que fue estable biológicamente (compost) y tuvo el mayor contenido de nitrógeno total.

Palabras clave: Ecología microbiana, lignocelulosa, biotransformación de cachaza, compost.

 

INTRODUCTION

Mexico ranks fifth in the world in sugar production. Production for the sugar harverst 2011-2012 was carried out in 54 of 57 sugarmills, in an area of 716,890 ha, and reached a production of 5,098,901 t of sugar (Comité Nacional para el Desarrollo Sustentable de la Caña de Azúcar [CONADESUCA], 2012) with a value close to 27 billion pesos, providing 11.6 % of the GDP of the primary sector and 2.5 % of the Manufacturing GDP (Secretaría de Economía, 2012). This agribusiness generates different waste; those generated in larger volumes are bagasse (25 to 30 %) and filter cake (3 to 5 %). Filter cake is a dark brown to black spongy organic material from filtration and washing of sediments in the process of clarification of cane juice (Zérega, 1993; Arreola-Enriquez et al., 2004), presenting a moisture content of 70 - 80 %, content of 0.79 - 2.2 % nitrogen and reaching a C:N ratio of between 12:4 to 30:1.

Filter cake has the ability to improve physical, chemical and microbiological properties of soil, and temporarily increases the cation exchange capacity (CEC) and retains moisture. However, it has been reported that the application of fresh organic material produces crop damage due to the decomposition process, therefore, several authors suggest that this material should be subjected to a process of decomposition such as composting (Hernández et al., 2008) before using it.

Composting is a bio-oxidative process that allows the stabilization of organic material. This process can be facilitated by stacking this material, and giving suitable conditions of aeration and moisture allowing microorganisms to grow and degrade structures comprising plant materials (hemicellulose, cellulose and lignin). The combinations of lignin-cellulose components of organic materials and the diversity of conditions where compost can be made impede the clarification of how different biotic and abiotic factors affect the activity of microbial populations (Cunha-Queda, Ribeiro, Ramos, & Cabral, 2007; Velasco-Velasco, Parkinson, & Kuri, 2011). Understanding how different factors regulate the activity of microbial populations in the composting process remains essential despite controversies, since these organisms could provide information to assess the process, quality, degradation rate and finally the maturity of the product (Vargas-García, López, Suárez, & Moreno, 2005).

The dynamics of the carbon:nitrogen (C:N) ratio becomes very important in the management of the composting process in accordance with microbial activity. Nitrogen has a special attention during the mineralization process, composting and particularly in the processes of nitrification and denitrification of nitrate and ammonium, respectively. An inefficient management during the composting process promotes nitrogen losses via volatilization of ammonia and nitrous oxide, and nitrate leaching. It also affects the final nutritional value of compost and thus its economic value (Tiquia, 2002; Bernal, Alburquerque, & Moral, 2009; Velasco-Velasco et al., 2011).

The objective of this research was to study the microbial dynamics of bacteria, fungi and ligninolytic microorganisms during composting process of filter cake reactivated with chicken manure in different proportions, quantify the evolution of carbon dioxide, total nitrogen, ammonium and nitrate content to obtain compost with higher content of total nitrogen.

 

MATERIALS AND METHODS

This research was conducted from October 2011 to January 2012 in the vermicomposting module of the Department of Soil Microbiology at the Postgraduate College, Campus Montecillo, Estado de México. Located at 2,250 m altitude, latitude 19° 29' N and longitude 98° 54' W. The type of climate is Cw, temperate, subhumid with summer rains (García, 2005).

 

Origin and content of the material used

Chicken manure was obtained from a chicken farm which is located in Córdoba, Veracruz to prepare the substrates studied. The filter cake was acquired from the sugarmill "Potrero" located in Atoyac Veracruz. The filter cake used had five months of being accumulated. Chemical analyses of the raw material were performed at the Laboratory of Environmental Sciences, Departament of Hydrosciences at the Postgraduate College Campus Montecillo (Table 1).

 

Setting the experiment

The experimental unit consisted of a 68 liter capacity plastic container (59.7 cm long x 46.7 cm wide x 41 cm high) with lid; in this container, 50 kg (fresh base) of the mixture of filter cake with chicken manure were placed according to the proportions listed below. Four substrates were evaluated: 100 % filter cake and 0 % chicken manure (10:0 v/v); 90 % filter cake and 10 % chicken manure (9:1 v/v); and 70 % filter cake and 30 % chicken manure (7:3 v/v); 50 % filter cake with 50 % chicken manure (5:5 v/v). These mixtures were aerated by turnings at 7, 24, 30 and 79 days after the experiment was set up. Water was added by every turning, to maintain 65 % gravimetric moisture in the substrate during the 87 days of composting (Radulovich, 2009).

 

Study variables and experimental design

The experiment was carried out using a completely randomized design with three replications. The experiment was implemented on October 28, 2011, samples were taken at 12, 26, 47, 75 and 87 days after the experiment was established. The experimental units were placed on soil, in a room covered with zinc plate. Three subsamples of about 400 g of compost at 25, 15 and 5 cm depth were taken at each sampling. The three subsamples were mixed to obtain a composite sample.

The technique of dilutions and plate count was used to determine the number of microorganisms present in the study treatments (Robert, 1990). The microbiological variables evaluated were: Total Bacteria (TB) on nutrient agar culture (Wollum, 1982), Total Fungi (TF) on potato dextroxa agar culture (Wollum, 1982) and ligninolytic microorganisms on culture suggested by Subba R., (1992) containing tannic acid and malt extract. The boxes were incubated at 28 °C for 3-7 days and the grown colonies (Clark, 1965) were counted.

The substrate temperature in the container was measured in the central part of the experimental units; readings were taken three times per week in the morning and were taken in the middle part of the experimental units. The room temperature was measured with a WhatchDog micro-station Series 1000 Spectrum^® Technologies, Inc. model 1425. The reading of the room temperature was taken every hour during the 87 days of the experiment.

The pH and electrical conductivity (EC) were determined in a ratio 1:5 (compost: water). Total Nitrogen (TN) was analyzed by the Kjeldahl method (Bremner & Mulvaney, 1982), NH⁺₄-N and NO₃^-N were determined with KCI 2M solution using the micro-Kjeldahl distillation method (Hesse, 1971). The organic matter was analyzed based on the method of Walkley and Black (1934). Calcium, magnesium, potassium, phosphorus, sulfur, sodium, copper, manganese, iron, zinc and boron were solubilized by digestion of the compost in 9 ml of nitric acid and were quantified by inductively coupled plasma emission spectroscopy model Optima 5300DV, Perkin Elmer.

Microbial respiration was measured using a portable meter, Spectrum Technologies, Inc. (Plainfield, IL) model Telaire® 7001 with an accuracy of ± 50 ppm with a resolution of±1 ppm. Microbiological data were transformed to logarithmic base (Log₁₀) for analysis of variance (ANOVA) and mean comparison (LSD_{0 05}) using the Statistical Analysis System (SAS) version 9.0 (SAS Institute, 2004).

 

RESULTS AND DISCUSSION

Temperature

Room temperature recorded during the 87 days when the experiment was developed provided a maximum and minimum temperature of 38.2 and -1.6 °C, respectively. The average temperature was 15 °C. The substrates with higher content of chicken manure (treatments 7:3 v/v and 5:5 v/v) showed higher temperatures compared to the substrates with lower content. Thus, the substrate of treatment 5:5 v/v resulted in a maximum and minimum temperature of 25.6 and 13 °C respectively and an average temperature of 18.57 °C; while the substrate of treatment 10:0 v/v had a maximum temperature of 20.3 °C, minimum temperature of 11.3 °C and average temperature of 14.97 °C (Figure 1). In this regard, Tiquia (2002) mentions that the increase in temperature is associated with an increased rate of decomposition, while the decrease in temperature is related to the microbial activity decline and labile fractions of the organic matter.

 

Microbial populations

Total bacteria: Treatments 9:1 v/v, 7:3 v/v and 5:5 v/v showed their maximum values at 10 and 24 days between 9.49 and 9.82 log units (ULog); and the lowest values were observed consecutively on days 45 and 87 with 8.62 and 7.96 ULog, respectively. This was probably due to depletion of the source of labile nitrogen in the substrate. In the last sampling (87 days), substrates with the highest values of total bacterial populations were 9:1 v/v and 7:3 v/v; the substrate with the lowest bacterial population was the treatment 10:0 v/v, this indicates the influence of the chicken manure, on the other materials in total bacterial populations due to nitrogen concentrations (Figure 2).

Total Fungi: TF populations showed no statistically significant differences during the composting process. Substrate 10:0 v/v showed low populations ranging from 4.4 to 5.0 ULog, substrate 9:1 showed three peaks of activities at 10, 45 and 87 days with values of 5.33, 5.49 and 5.33 ULog, respectively, and substrate 7:3 v/v at 87 days had 5.58 ULog, with the highest amount of fungal populations. The substrate 5:5 v/v showed a maximum in their populations at 73 days (Figure 2). In this regard Tuomela, Vikman, Hatakka, & Itävaara (2000) mention that fungi require a moderate level of nitrogen for their development, which is consistent with that observed in the present experiment. Adding chicken manure to filter cake meant an increase of nutrients which has been related to increased fungal populations. Chunha-Queda et al. (2007) mention that bacteria could consume nutrients inhibiting the growth of fungi. TF's population remained almost constant throughout the composting process. This may be because fungi are mostly mesophilic, which according to Dix and Webster (1995) can be found at temperatures between 5 and 37 °C, but their optimal development is between 25 and 30 °C, thus the substrate 5:5 v/v was the only reaching a maximum temperature of 25.6 °C.

Ligninolytic microorganisms: In substrates 10:0 v/v, 9:1 v/v 7:3 v/v the highest populations were observed at the earliest stage as the proportion of manure was higher. In these cases, a higher content of total nitrogen allowed to increase rapidly ligninolytic microorganisms population. The substrate 10:0 v/v, showed its maximum population of ligninolytic microorganisms at day 45 (5 ULog); while the substrate 9:1 v/v, reached the largest populations of this microbial group at days 10 and 24 (5.67 and 5.51 ULog). Moreover, the substrate 7:3 v/v showed a maximum at 10 days (6.42 ULog). On the other hand, the substrate 5:5 v/v which showed no peaks of maximum growth in any of the samples could be due to an excess amount of total nitrogen. Toumela et al. (2000) mention that for lignin degradation low nitrogen content (Figure 3) is required.

 

Nitrogen dynamics during composting

The concentration of TN increased in all treatments (Figure 3). According to Liu, Xiu-Hong, Hong-Tao, & Ying, (2011) this rise is expected due to a net loss of dry mass through carbon loss by CO₂ volatilization. The substrate 5:5 v/v at the end of the experiment had the highest percentage (4.66 %) of TN (Figure 3); this value is greater than that observed by Hernandez et al. (2008), who reports for the compost of filter cake 1.6 % of final TN, which indicates that the addition of chicken manure increased the percentage of TN in the compost. The NH⁺₄-N for substrates 10:0 v/v and 9:1 v/v showed no statistical differences over time; unlike the substrates 7:3 v/v and 5:5 v/v with a decrease, the substrate 5:5 v/v had the highest amount of NH⁺₄-N with 268.33 mg∙kg^-1 at the end of the experiment. In this regard, Méndez, Sánchez, Palma-López, & Salgado, (2011) reported for a compost of 100 % filter cake supplemented with 0.5 % N and one without additive 1,195.1 and 246.2 mg∙kg^-1 of NH⁺₄-N, respectively (Figure 3). The final values of TN for all substrates may be indicative of the maturity of the substrates. In this regard Raj & Antil, (2011) indicates that values lower than 400 mg∙kg^-1 of NH⁺₄-N are an indicator of the maturity of the compost. NO^-₃ -N showed an increase from its initial value; the final values show no significant differences among them and the final values were found between 483.00 and 657.19 mg∙kg^-1 for substrates 7:3 v/v and 5.5 v/v respectively (Figure 3). Mendez et al. (2011) reported for a compost of 100 % filter cake by adding 0.5 % of N and one without additive 1,372.8 and 210.9 mg-kg^-1 of NO^-₃-N at the end of the composting process, respectively.

 

Respiration

Figure 4 shows the behavior of CO₂ during the composting process. The treatments with higher production of CO₂ were the substrates 7:3 v/v and 5:5 v/v, reaching values of 6,908 and 5,573 ppm of CO₂. The temperature values reached in substrates 10:0 v/v and 9:1 v/v were the lowest, which is consistent with the results of Velasco-Velasco, Figueroa-Sandoval, Ferrera-Cerrato, Trinidad-Santos, & Gallegos-Sánchez, (2004) who observed that at higher temperature the production of CO₂ increases. Kalamdhad, Pasha, & Kazmi (2008) consider that the most direct technique for measuring the stability of compost is the evolution of CO₂, as it is directly correlated with aerobic microbial respiration, which actually measures the respiration and therefore the biological activity of aerobic microbial groups. This means that the organic materials must control factors such as humidity, aeration and nitrogen-carbon ratio between 20 and 30:1, allowing microbial groups to enhance their populations to accelerate the decomposition of carbon compounds by microorganisms to achieve a microbial stabilization in a short time, that can be measured by CO₂ emission as an indicator of the maturity of the compost.

The substrates with higher proportion of chicken manure (7:3 and 5:5 v/v) showed higher concentrations of CO₂ during the composting process; which would explain the largest populations of TB and ligninolytic microorganisms in these substrates.

 

C:N ratio

Table 2 shows the final values of the carbon:nitrogen ratio of the substrates evaluated. It is observed that the greater the amount of chicken manure added to the filter cake the lower the carbon:nitrogen ratio. This correspondence is one of the main features that describe the composting process, the reduction of this ratio is because during the composting process C becomes CO₂ (Golueke, 1981; Vourinen & Saharinen, 1997), because it is emitted from the mass of the compost as a metabolic product, the content of N per unit of material increased, which resulted in the decrease of the C:N ratio (Vuorinen & Saharinen, 1997; Raj & Antil, 2011). The substrate temperature and microbial respiration, measured by the volatilization of CO₂ and the C: N ratio are considered some of the main indicators of compost maturity.

 

CONCLUSION

The addition of chicken manure to stored filter cake, reactivated total bacterial populations, total fungi and ligninolytic microorganisms. Microbial populations were strongly influenced by factors such as temperature and nutrients of the substrates. This affected, in greater ULog in total bacteria and ligninolytic microorganisms of substrates with higher proportion of chicken manure (7:3 and 5:5 v/v). Similarly, the reactivation of microbial activity was evidenced by the higher production of CO₂. The addition of chicken manure increased the concentration of total nitrogen at 4.72 % and at 600 mg∙kg^-1 of nitrates; while the ammonia concentration was reduced to less than 300 mg∙kg^-1 in the final product, and consequently reduced the carbon:nitrogen ratio to 4:1. The mixture of chicken manure and filter cake in proportion 5:5 v/v increased the microbial activity and the nutrient content, therefore the quality of the compost.

 

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