M. Eiroa

Evaluation of the biomethane potential of solid fish waste

Manufacturing processes in fish canning industries generate a considerable amount of solid waste that can be digested anaerobically. The aim of this research was to study the biochemical methane potential of different solid fish waste. For tuna, sardine and needle fish waste, around 0.47g COD-CH(4)/g COD(added) was obtained in batch experiments with 1%TS; whereas for mackerel waste, the methane production attained 0.59g COD-CH(4)/g COD(added). The increase in the waste/inoculum ratio, from 1.1-1.3 to 2.8-3.3g VS(waste)/g VS(inoculum), led to overload due to VFA and LCFA accumulation. Afterward, co-digestion assays of fish waste with gorse were undertaken but the biochemical methane potential did not improve.

The SHARON process in the treatment of landfill leachate.

The purpose of this paper was to study the partial nitrification of the nitrogen present in a landfill leachate applying the SHARON process in order to obtain a suitable effluent to the ANAMMOX process. As a first step, the SHARON reactor was fed anaerobically pre-treated leachate at an ammonium concentration of 2,000 mg N/L (1.1 kg N/m(3) d). In such conditions, the average ammonium and nitrite concentrations in the effluent were 775 mg N/L and 1,225 mg N/L, respectively. During this period the COD removal was very low since most of the biodegradable organic matter was removed in the anaerobic pre-treatment. Afterwards, the SHARON reactor was fed leachate without a previous treatment and the efficiency of the partial nitritation diminished. As well, the COD removal increased, achieving a percentage around 28%.

Bioreactors for the Treatment of Industrial Waste Gases Containing Formaldehyde and Other Aliphatic Compounds

Over the past decades, bioreactors have proven to be efficient and cheap systems for the abatement of a variety of common air pollutants. Among their main advantages, one should mention their high efficiency, minimal side-effects on health and on the environment and their relatively low cost. Three basic types of bioreactors can be distinguished [1]: Bioscrubber (Fig. la): composed of an absorption column, where the pollutants are absorbed in a liquid phase, and a stirred tank bioreactor, in which biodegradation takes place. Trickling biofilter (Fig. lb): consists of a fixed film bioreactor, which is continuously fed a liquid medium. Biofilter (Fig. lc): similar to the previous one, but no continuous supply of liquid medium is used (liquid supply can be periodical or simply non-existent).

Formaldehyde biodegradation and its effect on the denitrification process.

Simultaneous formaldehyde biodegradation and denitrification in batch assays and in a continuous lab-scale reactor were studied. In batch assays, initial biodegradation rates between 0.7 and 3.3 g CH2O g VSS-1 d-1 were obtained at formaldehyde concentrations between 300 and 2150 mg l-1. The denitrification process was affected by the presence of formaldehyde. The nitrite accumulation increased with the initial formaldehyde concentration. In the continuous reactor, removal efficiencies above 98.5% were obtained at formaldehyde loading rates between 0.37 and 2.96 kg COD m-3 d-1 (625 - 5000 mg CH2O l-1). Formaldehyde removal led to the appearance of methanol and formic acid in the medium. Denitrification process was almost complete (around 99.7%) at nitrogen loading rates up to 0.44 kg N-NO3 - m-3 d-1. Nitrite occasionally appeared in the effluent at concentrations less than 2.9 mg l-1. The composition of the biogas indicated that denitrification and methanogenesis occurred simultaneously in the same unit.