Staged and non-staged anaerobic filters: microbial activity segregation, hydrodynamic behaviour and performance

Abstract

: This work describes a comparative study of staged and non-staged anaerobic Ðlters for treating a synthetic dairy waste under similar operating conditions. The e †ect of increasing the substrate concentration from 3 to 12 g COD dm~3 at a constant hydraulic residence time (HRT) of 2 days was evaluated with respect to overall reactor performance, biogas production, volatile fatty acids proÐles along the height, methanogenic and acidogenic activity distribution, and hydrodynamic behaviour. The potential maximum speciÐc methanogenic activity against acetate, hydrogen, propionate and butyrate and the lactose speciÐc activity were determined for sludge sampled from three di †erent points in each reactor, under two operating conditions (inÑuent COD of 3 and 9 g COD dm~3). Although all trophic groups involved in the anaerobic process were found throughout the reactors, it was possible to identify di †erent speciÐc sludges at di †erent heights in both reactors. Performances of the two conÐgu-rations were very similar under the operating conditions tested and the plug Ñow behaviour of the staged reactor was clearly reduced when the inÑuent concentration increased from 3 to 9 g COD dm~3.1998 Society of Chemical Industry ( J. Chem. T echnol. Biotechnol. 73, 99È108 (1998)

Anaerobic treatment of dairy wastewaters: a review

“…The system could generate approximately 770 l methane (CH 4 )/day. A comparative study of staged and non-staged anaerobic filters treating synthetic dairy wastewaters was conducted at an HRT of 2 days and in a substrate concentration range of from 3 to 12 g COD/l [70]. The authors reported that the performances of both reactors were very similar under the operating conditions tested.…”

Staged and non-staged anaerobic filters: performance in relation to physical and biological characteristics of microbial aggregates

“…The two anaerobic filters have been described elsewhere 8. In the non‐staged configuration (AFI) the initial liquid volume was 14.2 dm 3 and in the staged configuration (AFII) it was 17.7 dm 3 .…”

“…After an initial operation period of 495 days described elsewhere,8 the substrate concentration was increased from 9 to 12 g COD dm −3 during a short period (between days 596 and 628), but returned to 9 g COD dm −3 thereafter. In the staged digester (AFII), the HRT was decreased from 2 days to 10 h by applying lateral feedings at the inlet of the second (double feed‐DF) and third stages (triple feed‐TF).…”

“…El‐Shafie and Bloodgood6 studied the degradation of a synthetic complex wastewater in a staged anaerobic filter with six compartments and Cheung et al 7 operated and characterised a staged fixed bed process with three compartments. In a previous work Alves et al 8 compared a staged with a non‐staged anaerobic filter and concluded that, under the operating conditions tested, there was no advantage in using the staged system. The physical properties of the microbial aggregates such as size and settling velocity varied along the height.…”

Advanced Monitoring and Supervision of Biological Treatment of Complex Dairy Effluents in a Full-Scale Plant

“…In this context, anaerobic processes have been proved in past decades as a successful alternative to overcome these difficulties (1,5). In many cases chemical oxygen demand (COD) removal efficiencies attained in anaerobic reactors have been higher than 80%, showing the feasibility of anaerobic technology to treat this kind of wastewaters (6).…”