Vertical Flow Beds Research Articles

Enhancing nitrification in vertical flow constructed wetland utilizing a passive air pump

Nitrification of simulated secondary effluent solution using a variant of the vertical flow bed constructed wetland was studied. In this system oxygen required for the nitrification process is supplied by a passive air pump. The passive air pump is based on a fill and draw cycle, where oxygen depleted air is removed from the system while fresh air is introduced. Each volume of effluent drained is displaced by an equal volume of fresh air. Spatial and temporal oxygen distribution in the system as a function of drained effluent volume was investigated. Experimental results of nitrification and the corresponding oxygen consumption show good agreement with theoretical calculations based on physico–chemical considerations. Observations show that while oxygen distribution within the media was found to be non-uniform at the beginning of each cycle, it approached more uniform distribution with time. The latter resulted mainly from diffusion of oxygen in the gaseous phase.

Treatment of Dilute Piggery Effluent with Vertical Flow Reed Beds

AbstractWashwater from pig pens was led from a lagoon and treated in a series of vertical flow reed beds over 2 yr. A recirculation component was added in the second yr. Five‐day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), ammonium‐N (NH4‐N), and nitrate‐N (NO3‐N) were measured during the late winter/early spring periods for the 2 yr. Values of KBoD, to describe performance of horizontal flow reed beds, were determined for the vertical flow beds and compared with values derived from the literature. Maximum BOD5 removal was 96%, but averaged 65 and 61% over the first and second year periods, respectively. Performance of each stage, as indicated by percent removal of BOD5, was best described by an inverse logarithmic function of hydraulic load. Ponding was a problem, indicating a need for control of organic loading. Efficient nitrification was not achieved so that the treatment did not result in waste suitable for direct discharge to surface water.

N- and COD-removal in vertical-flow systems

Examination of COD-degradation and N-conversion within vertical flow systems and determination of influencing factors was done on constructed wetlands as well as on unplanted soil columns at laboratory scale. Topics of investigation were influent and effluent concentrations and removal efficiency of vertical flow beds, soil water composition at different depths and N-conversion activity with different operating methods, different hydraulic loadings (50, 100, 150 mm/d) and different soil materials. The extent of degradation and conversion are especially determined by O2-supply which can be influenced by operating method, hydraulic loading and soil material. COD-degradation and N-conversion take mainly place in soil depths down to 20 cm depending on the O2-supply and soil material. In general a sufficient O2-supply in an intermittently loaded vertical flow bed leads to a COD- and NH4-reduction ≥ 90% and prevents a Ntot-degradation of more than 50%. The determination of N-conversion activities of different soil samples has shown that nitrification activity as well as nitrate reductase activity have their maximum in soil depths down to 10 cm.

Investigation of alternative method for nitrification in constructed wetlands

Nitrification of secondary effluent using a variant of the vertical flow bed system was investigated. In this vertical flow bed oxygen required for the nitrification process is supplied by a passive air pump. The passive air pump is based on a fill and draw cycle, where oxygen depleted air is removed from the system and fresh air is introduced. Each volume of effluent drained is displaced by an equal volume of fresh air. Experimental results of nitrification and the corresponding oxygen consumption show good agreement with theoretical calculations based on physico-chemical considerations.

Investigation of alternative method for nitrification in constructed wetlands

Nitrification of secondary effluent using a variant of the vertical flow bed system was investigated. In this vertical flow bed oxygen required for the nitrification process is supplied by a passive air pump. The passive air pump is based on a fill and draw cycle, where oxygen depleted air is removed from the system and fresh air is introduced. Each volume of effluent drained is displaced by an equal volume of fresh air. Experimental results of nitrification and the corresponding oxygen consumption show good agreement with theoretical calculations based on physico-chemical considerations.

N- and COD-removal in vertical-flow systems

Examination of COD-degradation and N-conversion within vertical flow systems and determination of influencing faclors was done on constructed wetlands as well as on unplanted soil columns at laboratory scale. Topics of investigation were influent and effluent concentrations and removal efficiency of vertical flow beds, soil waler composition at different depths and N-conversion activity with different operating methods, different hydraulic loadings (50, 100, 150 mm/d) and different soil materials.The extent of degradation and conversion are especially determined by O2-supply which can be influenced by operating method, hydraulic loading and soil malerial.COD-degradation and N-conversion take mainly place in soil depths down to 20 cm depending on the O2supply and soil material. In general a sufficient O2-supply in an intermittently loaded vertical flow bed leads to a COD- and NH4-reduction ≥ 90% and prevents a Ntot-degradation of more than 50%. The determination of N-conversion activities of different soil samples has shown that nitrification activity as well as nitrate reductase activity have their maximum in soil depths down to 10 cm.

An active charge, passive discharge floor space heating system

This space heating system has a rockbed beneath and in contact with the floor of a dwelling, which is heated by radiation and convection from the floor. The ability of the heating system to maintain comfort conditions with no additional energy input is discussed and it is shown that the system is more suitable for use in mild climates than severe ones. Experimental work on horizontal air flow rockbeds is reported and shows that shallow beds can be designed in the same way as vertical air flow beds. The influence of natural convection on the effective thermal conductivity of the experimental rockbeds is reported.