Physical–anaerobic–chemical process for treatment of dairy cattle manure

An overall treatment process for the removal of nitrogen, methane production and obtention of valuable fertilizers from dairy manure has been investigated in laboratory scale. Solid and liquid fractions were separated by flocculation and screening. The solid fraction contained 81.6%, 84.4%, 58.6% and 85.2% of TS, VS, TKN–N and PT originally present in manure. Batch anaerobic digestion of this solid fraction at 50 °C resulted in methane production of 29.0 L CH4/kg. The liquid fraction, free of suspended solids, was satisfactorily treated at 35 °C in an upflow anaerobic sludge blanket reactor operating stably at an organic loading rate of 40.8 g COD/(L·d) reaching a methane production of 10.3 L CH4/(L·d). Accumulation of volatile fatty acids did not occur. Ammonia nitrogen concentration in the anaerobic effluent fluctuated between 850–1170 mg View the MathML sourceNH4+–N/L and was reduced to values less than 100 mg View the MathML sourceNH4+–N/L by struvite precipitation

Evaluation of different types of anaerobic seed sludge for the high rate anaerobic digestion of pig slurry in UASB reactors

Three different types of anaerobic sludge (granular, thickened digestate and anaerobic sewage) were evaluated as seed inoculum sources for the high rate anaerobic digestion of pig slurry in UASB reactors. Granular sludge performance was optimal, allowing a high efficiency process yielding a volumetric methane production rate of 4.1 L CH4 L-1 d-1 at 1.5 days HRT (0.248 L CH4 g-1 COD) at an organic loading rate of 16.4 g COD L-1 d-1. The thickened digestate sludge experimented flotation problems, thus resulting inappropriate for the UASB process. The anaerobic sewage sludge reactor experimented biomass wash-out, but allowed high process efficiency operation at 3 days HRT, yielding a volumetric methane production rate of 1.7 L CH4 L-1 d-1(0.236 L CH4 g-1 COD) at an organic loading rate of 7.2 g COD L-1 d-1. To guarantee the success of the UASB process, the settleable solids of the slurry must be previously removed

Biogas production from various typical organic wastes generated in the region of Cantabria (Spain): methane yields and co-digestion tests

Batch trials were carried out to determine the methane potential yields of some typical organic wastes generated in the region of Cantabria (Spain): cocoa shell, cheese whey and sludges from dairy industry. Anaerobic co-digestion trials of these wastes with dairy manure were also investigated in batch at 35˚C. Cheese whey obtained similar methane yields than dairy manure, between 17.5 and 19.3 L CH4 kg−1 cheese whey compared with 18.0 L CH4 kg−1 manure. Methane yields of various sludge samples collected from wastewater treatment facilities of dairy industries were influenced by its origin. Sludge samples from fat separation devices were the most productive in terms of specific methane yields compared with biological sludge from an aerobic reactor. Sludge samples from fat separator reached specific methane productivities of 350 and 388 L CH4 kg−1 VS (10.5 and 24.1 L CH4 kg−1 sludge), whereas biological sludge yielded 125 L CH4 kg−1 VS (12.6 L CH4 kg−1 sludge). The methane potential of sludge samples was influenced by solids content. Cocoa shell resulted to be an interesting waste for anaerobic digestion due to its high VS content, yielding 195 L CH4 kg−1 cocoa shell. It is a waste that can considerably improve methane yields in anaerobic co-digestion with dairy manure. However, at proportions of 10% cocoa shell, the process was hindered by hydrolysis of particulate matter. Anaerobic digestion at higher temperatures (thermophilic range) could be a better option for this kind of waste. Co-digestion of 5% cocoa shell with 35% dairy sludge and 60% dairy manure resulted in 80.5% higher methane production compared to anaerobic digestion of dairy manure alone

Solid – Liquid separation of dairy manure: distribution of components and methane production

Chemical treatment and screening can be an effective technique for separation of dairy cattle manure into a liquid fraction (LF) and a nutrient-rich solid fraction (SF). The optimum loading of a strong cationic polyacrylamide was found to be 43.9 g kg−1 of dry excreta. The separated SF contained 29.1% of the initial mass present in the manure and the chemicals added. The Volatile Solids (VS)/Total Solids (TS) ratio, which was 0.78 for the manure, rose to 0.82 for the SF and decreased to 0.63 in the LF. Furthermore, the SF retained 76.1, 79.9, 59.4 and 87.4% of TS, VS, Total Kjeldahl Nitrogen and Total Phosphorus, respectively. In the LF, the ratio of filtrate chemical oxygen demand (CODfiltrate) and COD due to volatile fatty acids (CODVFA) in relation to total COD (CODT) were 0.86 and 0.76, respectively. The percentage of anaerobically biodegradable chemical oxygen demand (CODBD) for the LF was 83.0%. Treatment of the LF in high loading anaerobic reactors would be possible due to these COD characteristics. Specific methane production in terms of VS for the separated LF was 0.580 m3 kg−1. For dairy manure and SF, it was 0.320 and 0.258 m3 kg−1, respectivel

Use of ash from sewage sludge in the preparation of desulfurant sorbents

This work aims to develop new uses for sewage sludge, which is a byproduct of municipal wastewater treatment plants, by examining the calcination of this waste, the characterization of ashes is obtained, and its use to prepare desulfurant sorbents. Samples of sewage sludge were obtained from a local municipal wastewater treatment plant. This plant applies a pre-treatment followed by a biological treatment, where anaerobic digestion and centrifugation reduces the sludge. Three samples were characterized (in humidity, volatile and fixed solids content), dried, and ignited at two temperatures, 550 and 750 C. The composition of the ash obtained at both ignition temperatures was studied by x-ray fluorescent spectroscopy and the BET specific surface area of the two ashes and of the prepared sorbents was measured. Ash composition was similar for the two temperatures tested, where the components were Si, Ca, Al, Fe, P, S, Mg, K, Cl, Zn and Ti. BET specific surface area values indicate that the lower temperature of calcination produces ash with the highest SSA values (18 m2/g against near 10 m2/g). Preparation of desulfurant sorbents was carried out by mixing the ash with CaO or Ca(OH)2 at room temperature and different experimental conditions. The BET SSA of the prepared desulfurant sorbents showed higher values for the sorbents prepared with the ashes obtained at the lowest temperature. The behaviour of the ash and the prepared sorbents was tested in a fixed bed reactor at 58 C with a flue gas containing 5000 ppm of SO2 with a relative humidity of 55%. Results in the desulfurization process show that the calcium from the sludge seems more efficient than the calcium added as CaO or Ca(OH)2 to prepare the sorbents

Anaerobic digestion of the liquid fraction of dairy manure in pilot plant for biogas production: Residual methane yield of digestate

The performance of the only dairy manure biogas plant in Cantabria (Northern coast of Spain) was evaluated in terms of liquid–solid separation and anaerobic digestion of the liquid fraction. Screened liquid fraction was satisfactorily treated in a CSTR digester at HRTs from 20 to 10 days with organic loading rates ranging from 2.0 to 4.5 kg VS/(m3 d). Stable biogas productions from 0.66 to 1.47 m3/(m3 d) were achieved. Four anaerobic effluents collected from the digester at different HRTs were analyzed to measure their residual methane potentials, which ranged from 12.7 to 102.4 L/g VS. These methane potentials were highly influenced by the feed quality and HRT of the previous CSTR anaerobic digestion process. Biomethanization of the screened liquid fraction of dairy manure from intensive farming has the potential to provide up to 2% of total electrical power in the region of Cantabria

Procedimiento para la gestión integral del estiércol de ganado vacuno lechero.

Procedimiento para la gestión integral del estiércol de ganado vacuno lechero que consta de una primera etapa de hidrólisis y acidogénesis, posterior separación físico química del residuo en dos fases, sólida y líquida. Para la fase sólida estabilización y recuperación energética de biogás mediante digestión anaerobia. Para la fase líquida estabilización y obtención de biogás en un reactor anaerobio de alta carga. Recuperación del nitrógeno amoniacal del efluente líquido como fosfato amónico magnésico sólido. El líquido resultante con bajo contenido amoniacal puede aplicarse al terreno, necesitando ahora mucha menor superficie para cumplir la normativa vigente. Este líquido también podría tratarse conjuntamente con agua residual urbana en las plantas biológicas aerobias de tratamiento, o bien mediante tecnología de membranas para obtener un efluente final que podría ser vertido a cauce público cumpliendo la normativa.Solicitud: 200402302 (22.09.2004)Nº Pub. de Solicitud: ES2292277A1 (01.03.2008)Nº de Patente: ES2292277B1 (01.11.2008

Effect of mixing on biogas production during mesophilic anaerobic digestion of screened dairy manure in a pilot plant

ABSTRACT:The effect of mixing on biogas production of a 1.5-m3 pilot continuous stirred tank reactor (CSTR) processing screened dairy manure was evaluated. Mixing was carried out by recirculation of reactor content with a mono pump. The experiment was conducted at a controlled temperature of 37±1°C and hydraulic retention times (HRTs) of 20 and 10 days. The effect of continuous and intermittent operation of the recirculation pump on biogas production was studied. At 10 days of HRT, the results showed a minimal influence of recirculation rate on biogas production and that continuous recirculation did not improve reactor performance. At 20 days of HRT, the recirculation rate did not affect reactor performance. Combination of low solid content in feed animal slurry and long HRTs results in minimal mixing requirements for anaerobic digestion.This work was supported by the Environment Council of the Government of Cantabria, Project 05-640.02-2174 entitled "Environmental Management of Dairy Cattle Manure in Cantabria" that enabled the completion of this work. This study was carried out in the framework of the NOVEDAR Consolider CSD2007-0005

Hidrodesoxigenación catalítica: uso de compuestos derivados de biomasa para la generación de biocombustibles

This study examined the importance of the hydrodeoxygenation (HDO) process, which allows us to obtain molecules with the necessary calorific potential to be useful as biofuels, an example of which is the phenol molecule, predominant in the mixtures remaining from cellulose liquefaction processes. The process was standardized using NiMoW trimetallic catalysts supported on Al2O3 which is based on two routes; the direct hydrogenation of the aromatic ring, followed by the cleavage of the Csp3-O bond and the direct cleavage by deoxygenation of the Csp2-O bond of the molecule, both routes are carried out simultaneously generating as reaction products: molecules such as: benzene, cyclohexane, cyclohexene, methylcyclopentane, cilohexanone and cyclohexanol. This type of catalysts present conversions of up to 92% of oxygenated molecules such as phenol, showing desirable textural properties (surface area, distribution and pore size), which allows a greater interaction in the reaction mixture, favoring the conversion, providing a promising alternative for purification processes of oxygenated molecules provided by nature for the optimization of obtaining biofuels.En este estudio se examinó la importancia del proceso de hidrodesoxigenación (HDO), el cual nos permite obtener moléculas con el potencial calorífico necesario para ser útiles como biocombustibles, ejemplo de ello es la molécula de fenol, predominante en las mezclas remanentes de procesos de licuefacción celulósica. Se estandarizó el proceso utilizando catalizadores trimetálicos NiMoW soportados en Al2O3 el cual se basa en dos vías; la hidrogenación directa del anillo aromático, seguido de la escisión del enlace Csp3-O y la escisión directa por desoxigenación del enlace Csp2-O de la molécula, ambas rutas se llevan a cabo simultáneamente generando como productos de reacción: moléculas como: benceno, ciclohexano, ciclohexeno, metilciclopentano, cilohexanona y ciclohexanol. Este tipo de catalizadores presentan una conversión de hasta el 92% de moléculas oxigenadas como el fenol, mostrando propiedades texturales deseables (área superficial, distribución y tamaño de poro), lo cual permite una mayor interacción en la mezcla de reacción, favoreciendo la conversión, proporcionando una alternativa prometedora para procesos de purificación de moléculas oxigenadas que provee la naturaleza para la optimización de obtención de biocombustibles. &nbsp

Problemas aritméticos compuestos de dos relaciones

En las investigaciones que estamos realizando en el campo aditivo utilizamos un conjunto de factores diferenciadores de los problemas de estructura aditiva, que presentamos a continuación