[Show abstract][Hide abstract] ABSTRACT: A better understanding of wastewater treatment with soil filters is important to optimise plant operation and reduce the risk of clogging. The article presents results of a treatment concept which uses a combination of SBR and vertical-flow sand filter technology. The SBR was mainly used for denitrification and sedimentation of substances in particulate form. Efficient nitrification was achieved by the planted sand filter. Degradation rates of 10gNH(4)-N/(m(2)xd) were measured for periods with peak loadings. The two-dimensional dynamic model reproduces the biofilm growth and decay of heterotrophic and autotrophic biomass. It is capable of describing the clogging of the sand filter by combining a biochemical and a geometric model. After calibration, the model was used for the calculation of maximum nitrogen degradation performances. Maximum degradation rates of 12gNH(4)-N/(m(2)xd) can be achieved if the COD/TKN ratio is reduced before to a level lower than that of municipal wastewater. The COD was further degraded in the filter than we expected comparing it with activated sludge plants. Within the soil filter a biofilm thickness of up to 110microm is simulated depending on the embankment of gravel and grains of sand. Sensitivity analysis of model parameters showed the high impact of the maximum autotrophic growth rate, the autotrophic yield, the diffusion coefficient for oxygen and the number of contact points of the single grains of sand.
Water Research 09/2008; 42(14):3899-909. · 4.66 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Physical, chemical and biological characteristics were investigated for aerobic granules and sludge flocs from three laboratory-scale sequencing batch reactors (SBRs). One reactor was operated as normal SBR (N-SBR) and two reactors were operated as granular SBRs (G-SBR1 and G-SBR2). G-SBR1 was inoculated with activated sludge and G-SBR2 with granules from the municipal wastewater plant in Garching (Germany). The following major parameters and functions were measured and compared between the three reactors: morphology, settling velocity, specific gravity (SG), sludge volume index (SVI), specific oxygen uptake rate (SOUR), distribution of the volume fraction of extracellular polymeric substances (EPS) and bacteria, organic carbon and nitrogen removal. Compared with sludge flocs, granular sludge had excellent settling properties, good solid-liquid separation, high biomass concentration, simultaneous nitrification and denitrification. Aerobic granular sludge does not have a higher microbial activity and there are some problems including higher effluent suspended solids, lower ratio of VSS/SS and no nitrification at the beginning of cultivation. Measurement with CLSM and additional image analysis showed that EPS glycoconjugates build one main fraction inside the granules. The aerobic granules from G-SBR1 prove to be heavier, smaller and have a higher microbial activity compared with G-SBR2. Furthermore, the granules were more compact, with lower SVI and less filamentous bacteria.
Water Science & Technology 02/2007; 55(8-9):403-11. · 1.10 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: With a series of buffer tank, activated pre-clarifier (SBR) and planted soil filters, it is possible to get a stable degradation and good effluent values in the case of unsteady inflow and changing concentrations. In the process presented here the activated pre-clarifier is working as a denitrification tank and the soil filter as a nitrification reactor. An automatic control manages the storm-water runoff, the water-recirculation returns the nitrate and provides a minimal feed. Experiences with this plant from 1999 to 2005 are given in this paper, research has been done in the project "Planted soil filters as a Biotechnological Process", founded by the German Federal Environment Foundation (DBU). A full scale pilot plant was built to treat wastewater from composting sides, with a 42 m3 SBR and a bed area of 2 x 550 m2 of the planted soil filters. Now, after six years of operation, the results are still satisfactory. Besides this pilot plant, landfill leakage and municipal wastewater have been treated in a technical scale plant with the same process in an 80 L SBR and 0.75 m2 vertical flow soil filter with good results.
Water Science & Technology 02/2007; 55(7):195-202. · 1.10 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: With the series of buffer tank, activated preclarifier and planted soil filters, it is possible to have a flexible operation by unsteady inflow and changing concentrations. An automatic control manages the storm-water runoff, and the water-recirculation provides a minimal feed, so the plant always runs effectively. Experiences with this plant since 1999 are given in the frame of the project “Planted Soil Filters as a Biotechnological Process”, founded by the German Federal Environment Fondation (DBU). Today, after six years of running, the results are still satisfactory.
[Show abstract][Hide abstract] ABSTRACT: A single stage nitritation–anammox pilot scale SBR was implemented to treat reject water from sludge dewatering. The SBR was operated with a new strategy, a combination of interval feeding with interval aeration using the oxidation–reduction potential (ORP) as the main process indicator parameter. The strategy allowed for optimized treatment of high nitrogen loaded reject water providing stable operation and achieving a nitrogen removal efficiency of more than 90% at a volumetric nitrogen load of 400 g N m−3 d−1. COD removal was also observed with an efficiency of around 70%.The concept of interval feeding monitored by the ORP also allowed for adjustments to changing environmental conditions (i.e., decrease in temperature) by adjusting the number of intervals per cycle and the number of cycles per day. The distinct swing in the ORP signal which showed the largest amplitudes and most distinct pattern of all monitored parameters made the ORP the most favorable control parameter for nitritation–anammox in this type of SBR.