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The effect of granular activated carbon (GAC) addition on the removal of diclofenac, ibuprofen, metoprolol, galaxolide and triclosan in a up-flow anaerobic sludge blanket (UASB) reactor was studied. Prior to the reactor studies, batch experiments indicated that addition of activated carbon to UASB sludge can decrease micropollutant concentrations in both liquid phase and sludge. In continuous experiments, two UASB reactors were operated for 260 days at an HRT of 20 days, using a mixture of source separated black water and sludge from aerobic grey water treatment as influent. GAC (5.7 g per liter of reactor volume) was added to one of the reactors on day 138. No significant difference in COD removal and biogas production between reactors with and without GAC addition was observed. In the presence of GAC, fewer micropollutants were washed out with the effluent and a lower accumulation of micropollutants in sludge and particulate organic matter occurred, which is an advantage in micropollutant emission reduction from wastewater. However, the removal of micropollutants by adding GAC to a UASB reactor would require more activated carbon compared to effluent post-treatment. Additional research is needed to estimate the effect of bioregeneration on the lifetime of activated carbon in a UASB-GAC reactor. [ABSTRACT FROM AUTHOR]

Although many publications are available on the fate of estrone (E1), 177beta;-estradiol (E2) and 17α-ethynylestradiol (EE2) during aerobic wastewater treatment, little is published on their fate under strictly anaerobic conditions. Present research investigated the digestibility of E1 and EE2, using digested pig manure, granular UASB sludge, UASB-septic tank sludge and activated sludge as inocula. Besides, actual concentrations were measured in a UASB septic tank treating black water. Under anaerobic conditions E1 is reduced to E2 but the extent of this reduction depends on type of inoculum. No significant loss of the sum of E1 and E2 and of EE2 was observed. Adsorption was responsible for a 32-35% loss of E1 and E2 from the liquid phase in the UASB septic tank and the effluent still contained considerable concentrations of respectively 4.02 µg/l and 18.79 µg/l for E1 and E2 with a large fraction present in conjugated form. No EE2 was detected in the UASB effluent. [ABSTRACT FROM AUTHOR]

Characterisation of greywater was conducted in two different greywater streams in the Netherlands (Groningen and Sneek). The concentrations of macropollutants and nutrients measured were very different in both streams; in particular the COD was 425 mg/L in Groningen's water whereas in Sneek it was 1,583 mg/L. The aerobic treatment of greywater in a fed-batch reactor led to a 90% removal of COD at different organic loading rates. Anaerobically, the removal reached 40% COD removal on average, the possible reason being the high amount of surfactants present in the influent. [ABSTRACT FROM AUTHOR]

The production of small amounts of well-stabilized biological sludge is one of the main advantages of upflow anaerobic sludge bed (UASB) reactors over aerobic wastewater treatment systems. In this work, sludge produced in three pilot-scale UASB reactors used to treat sewage under subtropical conditions was assessed for both stability and specific methanogenic activity. Stability of primary sludge from settling tanks and digested sludge from conventional sludge digesters was also measured for comparison purposes. Kinetic parameters like the hydrolysis rate constant and the decay rate constant were calculated. High stability was observed in sludge from UASB reactors. Methanogenic activity in anaerobic sludges was relatively low, probably due to the low organic matter concentration in influent sewage. Knowledge on sludge growth rate, stability, and activity might be very useful to optimize sludge management activities in full-scale UASB reactors. [ABSTRACT FROM AUTHOR]

The treatment of domestic sewage at low temperature was studied in a two-anaerobic-step system followed by an aerobic step, consisting of an anaerobic filter (AF) + an anaerobic hybrid (AH) + polyurethane-foam trickling filter (PTF). The AF+AH system was operated at a hydraulic retention time (HRT) of 3+6 h at a controlled temperature of 13°C, while the PTF was operated without wastewater recirculation at different hydraulic loading rates (HLR) of 41, 15.4 and 2.6 m³/m²/d at ambient temperature (ca. 15-18°C). The AF reactor removed the major part of the total and suspended COD, viz. 46 and 58% respectively. The AH reactor with granular sludge was efficient in the removal and conversion of the anaerobically biodegradable COD. The AF+AH system removed 63% of total COD and converted 46% of the influent total COD to methane. At a HLR of 41 m³/m²/d, the COD removal was limited in the PTF, while at HLR of 15.4 and 2.6 m³/m²/d, a high total COD removal of 54-57% was achieved without a significant difference between the two HLRs. The PTF was mainly efficient in the removal of particles (suspended and colloidal COD removal were 75-90% and 75-83% respectively), which were not removed in the anaerobic two-step. The overall total COD removal in the AF+AH+PTF system was 85%. Decreasing the HLR from 15.4 to 2.6 m³/m²/d, only increased the nitrification rate efficiency in the PTF from 22% to 60%. Also, at HLR of 15.4 and 2.6 m³/m²/d, PTF showed a similar removal for E. coli by about 2 log. Therefore, the effluent of AF+AH+PTF system can be utilised for restricted irrigation in order to close water and nutrients cycles. Moreover, such a system represents a high-load and a low-cost technology, which is a suitable solution for developing countries. [ABSTRACT FROM AUTHOR]

A Rotating Biological Contactor (RBC) was fed with raw domestic wastewater or anaerobic effluents. The experiments were conducted at increasing operational temperatures viz. 11, 20 and 30°C to assess the potential increase in removal efficiencies for the different COD fractions (CODtotal, CODsuspended, CODcolloidal and CODsoluble), E. coli and in the nitrification rate. The results clearly show that, the RBC at HRT of 2.5 h and OLR of 47 gCOD/m².d provided a very high residual CODtotal value of 228 mg/l when treating domestic wastewater. This was not the case as compared to the results obtained for the system when operated at the same HRT but at lower OLR's of 27, 20 and 14.5 g COD/m².d with a UASB effluent at operational temperatures of 11, 20 and 30°C respectively. The residual CODtotal values amounted to 100, 85 and 72 mg/l in the final effluents. Moreover, a high removal of ammonia and low residual values of E. coli was found for the RBC when treating a UASB effluent at operational temperature of 30°C as compared to the situation for treatment of domestic wastewater and UASB effluent at lower temperatures of 11 and 20°C. It can be concluded that an efficient pre-treatment of sewage implies a substantial reduction of OLR applied to the RBC and consequently improves the residual of CODtotal, ammonia and E. coli in the final effluent. Therefore, this study supports using a combined system UASB/RBC for treatment of domestic wastewater for reuse in irrigation. [ABSTRACT FROM AUTHOR]

Evaluates the performance of one-step upflow anaerobic sludge blanket (UASB) reactors treating fish processing wastewater of different lipid levels. Organic loading rates; Hydraulic retention times; Effluent and influent concentrations in the UASB reactors.

A mathematical description of the surface related hydrolysis kinetics for spherical particles in a batch digestion is presented as well as a verification of this model with particulate starch as a substrate. Three substrates containing starch with different particle size distributions (PSD) were used. Two were obtained from fresh potatoes by wet sieving and for the third substrate a commercially available starch was used. The substrates were batch digested at 30 deg. C with granular sludge as inoculum and the hydrolysis efficiency was measured and fitted with the model. The results revealed that the hydrolysis rates for the three substrates were equal, viz. 0.4 0.1 g starch/m2/hour. Moreover, for the commercial starch not only the hydrolysis efficiency but also the changes within the PSD of the starch was determined several times with the use of light microscopy and imageanalysis. The obtained experimental PSD showed good similarity with the theoretical PSD from model calculations. This shows that the surface of the particulate substrate is the key factor for the hydrolysisprocess. [ABSTRACT FROM AUTHOR]

Decentralized sewage treatment is more and more considered to be a sustainable way of waste(water) treatment. Three different options forthe on-site treatment of sewage in combination with VFY (Vegetable, Fruit and Yard waste) with anaerobic treatment as a central techniqueare presented. The collection system and therewith the composition and concentration of the sewage will determine the type of anaerobic technology and the process conditions to be applied. Model calculations are made for determining the HRT to be applied in a UASB system at an obliged SRT at a certain temperature. [ABSTRACT FROM AUTHOR]

This paper reviews recent technological developments in the filtration of primary effluent. Various studies show that single stage intermittent sand filters attain removal efficiencies of 90% COD, 95% BOD5, 30% TN, 40% TP and 99-99.9% FC at maximum BOD5 loads of around 10 g.m-2.d-1 and hydraulic loads of 5-10 cm.d-1. The permissible organic load can be enhanced by measures such as improved aeration and the use of multilayerfilters. Nitrogen removal can be enhanced to 70% by adding a C-source to the filter material or by using two-stage post- and pre-denitrification systems. High organic loading rates (up to around 100 g BOD5.m-2.d-1) are possible with aerated adsorbent foam as a medium. [ABSTRACT FROM AUTHOR]

The treatment of sewage at a temperature of 13 deg. C was investigated in three reactors (each 3.84 litre) a UASB and two anaerobic hybrid (AH) reactors with small sludge granules with an average diameter of 0.73 mm. The media used in the AH reactors were vertical polyurethane foam sheets. The reactors were operated at a HRT of 8 h. The use of small sludge granules and operating the reactors at low upflow velocity (1.8 m/d) improved suspended COD removal efficiencies for the UASB reactor. Moreover, the use of sheets in the AH reactors significantly increased suspended COD removal efficiencies as compared to the UASB and reached to 87% for pre-settled sewage treatment. The treatment of pre-settled sewage instead of raw sewage in AH reactors significantly increased colloidal and dissolved COD removal efficiencies with13% and 12% respectively and colloidal COD removal efficiency for the UASB reactor with 13%. At `steady state' for pre-settled sewage treatment, the AH reactors removed 64% of the total COD which is significantly higher by 4% than the UASB reactor. Therefore, the anaerobic treatment of domestic sewage at low temperature can be improved by treating pre-settled sewage in shallow AH reactors containing small sludge granules. [ABSTRACT FROM AUTHOR]

The application of one phase anaerobic wastewater systems for the treatment of complex wastewaters containing high amounts of suspended solids or lipids is usually limited by accumulation of these compoundsin the sludge bed. This accumulation reduces the solid retention time and methanogenic activity of the sludge. The aim of the presented research was to achieve removal of suspended solids or lipids in an Upflow Anaerobic Solids Removal reactor to make higher reactor loadingspossible. Raw sewage, waste activated sludge and dairy wastewater were pre-treated in an UASR reactor. When treating the raw sewage at 17deg.C and 3.0 HRT 65% of the suspended COD could be entrapped in thesludge bed. Treatment of 2 g COD/l waste activated sludge at 9.6h HRT and 20 deg.C resulted in 98% removal of the suspended COD. In both cases only 6--7% acidification of the complex wastewater took place. Dairy wastewater consists of mainly dissolved and colloidal COD. The lipids are surrounded by a protein membrane. These proteins will precipitate at pH <4.6 resulting in co-precipitation of the lipids. At 20deg.C and 4.5hHRT 57% of the lactose present in the wastewater was acidified, resulting in a pH of 4.0 and 98% lipids removal. it was concluded that the UASR reactor can achieve very high removal efficiencies for CODss and lipids, yet the retained COD is just partly hydrolysed. The produced sludge can be post-digested at thermophilic or mesophilic conditions to produce methane gas. [ABSTRACT FROM AUTHOR]