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

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

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

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