Coarse media filtration - an alternative to settling in wastewater treatment

2003 ◽  
Vol 47 (12) ◽  
pp. 81-88 ◽  
Author(s):  
H. Ødegaard ◽  
Z. Liao ◽  
A.T. Hansen

In this paper coarse media filtration has been analysed as an alternative to the traditional settling in primary, secondary and tertiary treatment of wastewater. Various filter media configurations were evaluated for enhanced primary filtration. It was found that a dual media configuration based on Kaldnes biofilm media (K1 and K2modified) were most suitable when taking both separation efficiency as well as filter run time into consideration. SS removal efficiencies of around 75% were achieved in the dual Kaldnes primary filter at around 20 m/h without any chemical addition and around 85% at low dosage (1-2 mg/l) of a high MW cationic polymer FO4440SH. In the latter case COD was removed by around 70%. Further experiments were carried out on a multi-media Kaldnes-Filtralite-Sand (KFS) filter for enhanced primary treatment as well as for secondary filtration directly downstream of a high-rate moving bed biofilm reactor, resulting in an extremely compact secondary treatment process. The secondary KFS-filter gave SS-removal efficiencies around 90% (effluent SS < 15 mg/l) and filter run times of around 24 hrs at filtration rates of 10 m/h (sludge loading rates of around 1 kg /m2h) when a small dose (2 mg/l) of polymer was used. It is also demonstrated that the primary filter may also be utilised as a pre-denitrification reactor. A denitrification rate of 1.5 kg NO3-Nequiv./m3d was achieved when the filter was operated at a filtration rate of 5 m/h.

2005 ◽  
Vol 51 (6-7) ◽  
pp. 421-430 ◽  
Author(s):  
E. Melin ◽  
T. Leiknes ◽  
H. Helness ◽  
V. Rasmussen ◽  
H. Ødegaard

The effect of moving bed biofilm reactor (MBBR) loading rate on membrane fouling rate was studied in two parallel units combining MBBR and membrane reactor. Hollow fiber membranes with molecular weight cut-off of 30 kD were used. The HRTs of the MBBRs varied from 45 min to 4 h and the COD loading rates ranged from 4.1 to 26.6 g COD m−2 d−1. The trans-membrane pressure (TMP) was very sensitive to fluxes for the used membranes and the experiments were carried out at relatively low fluxes (3.3–5.6 l m−2 h−1). Beside the test with the highest flux, there were no consistent differences in fouling rate between the low- and high-rate reactors. Also, the removal efficiencies were quite similar in both systems. The average COD removal efficiencies in the total process were 87% at 3–4 h HRT and 83% at 0.75–1 h HRT. At high loading rates, there was a shift in particle size distribution towards smaller particles in the MBBR effluents. However, 79–81% of the COD was in particles that were separated by membranes, explaining the relatively small differences in the removal efficiencies at different loading rates. The COD fractionation also indicated that the choice of membrane pore size within the range of 30 kD to 0.1 μm has very small effect on the COD removal in the MBBR/membrane process, especially with low-rate MBBRs.


2004 ◽  
Vol 4 (1) ◽  
pp. 23-33
Author(s):  
H. Ødegaard ◽  
Z. Liao ◽  
E. Melin ◽  
H. Helness

Many cities need to build compact wastewater treatment plants because of lack of land. This paper discusses compact treatment methods. An enhanced primary treatment process based on coarse media filtration is analysed. A high-rate secondary wastewater treatment process has specifically been investigated, consisting of a highly loaded moving bed biofilm reactor directly followed by a coagulation and floc separation step. The objective with this high-rate process is to meet secondary treatment effluent standards at a minimum use of chemicals, minimum sludge production and minimum footprint. It is demonstrated that the biofilm in the bioreactor mainly deals with the soluble organic matter while coagulation deals with the colloidal matter. The bioreactor may, therefore, be designed based on the soluble COD loading only, resulting in a very compact plant when a compact biomass/floc separation reactor (i.e. flotation or direct filtration) is used. The paper reports specifically on the coagulant choice in flotation and filter run time in direct filtration.


2004 ◽  
Vol 39 (4) ◽  
pp. 449-456 ◽  
Author(s):  
Jian Guo Li ◽  
Harold Horneck ◽  
David Averill ◽  
J. Alex McCorquodale ◽  
Nihar Biswas

Abstract Experimental investigations were conducted to evaluate the effectiveness of a retention treatment basin (RTB) with polymer coagulation for the treatment of combined sewer overflows (CSO) at high hydraulic loading rates. The TSS removal efficiency of the pilot-scale RTB at a surface overflow rate (SOR) of 11 m/h was approximately 35% without chemical addition, and 80% with a polymer dosage range of 5 to 10 milligrams per gram of influent TSS. The results demonstrated that the use of polymer coagulation significantly improved TSS removal and allowed the SOR in the RTB to be significantly increased, resulting in smaller treatment units. An empirical relationship was established to estimate removal efficiencies as a function of overflow rate. The results also compared settling characteristics of CSO, obtained from long column tests, to removal efficiencies in the high-rate RTB.


2020 ◽  
Vol 58 (3A) ◽  
pp. 211
Author(s):  
Quan Truong Nguyen ◽  
Quan Truong Nguyen ◽  
Ha Thi Nguyen

The objective of this study is to investigate the performance of Anaerobic Moving Bed Biofilm Reactor (MBBR) on the removal of organic matters (using COD and TSS values) in piggery wastewater using two kinds of carrier: Polyurethane (PU) and Polyethylene (PE) - Different organic loading rates (OLRs) varying from 4 to 10 gCOD/l/day with controlled temperature 37±2oC, pH 7.0-7.5 were investigated. The seeded sludge was collected at the anaerobic tank of the wastewater treatment plant of the Sabeco Beer Manufacturing Plant (Nam Tu Liem district, Hanoi) and grown in the MBBR for 15 days. For porous PU material, the COD and TSS removal efficiencies achieved 69.7 and 67.3% and 54.9 and 65.5% at OLR 4 and 6 gCOD/l/day, respectively.  Whereas for wheel shape PE material, it was found that the COD removal efficiencies were slightly higher with OLR of 6  gCOD/l/day (71%%), even with higher OLR at 10 gCOD/l.day, the COD removal efficiency didn‘t seem to significantly increase (73.3 %). For TSS removal, in comparison between PU and PE, the later found slightly better with the same OLRs of 4 and 6 gCOD/l/day, reaching 63.2 and 67 %, respectively. However, TSS removal efficiencies were found to be higher with PE carrier at higher OLR, reaching 72% at 10 gCOD/l/day.


2006 ◽  
Vol 1 (4) ◽  
Author(s):  
H. Zhao ◽  
C. Woods ◽  
J. Parker ◽  
S.-N. Hong

This paper presents the results of a two-year pilot evaluation of floating media biological aerated filters (BAFs). The pilot consists of two stages - tertiary nitrification (N) filter followed by post denitrification (DN) filter. The focus of the pilot study was to determine the BAFs’ capacity to meet stringent tertiary treatment requirements in treating the effluent from a conventional activated sludge process. It was demonstrated that the two-stage BAF system, on a 30-day average basis, is capable of achieving 1) a total nitrogen (TN) requirement less than 3 mg/L, 2) a total phosphorus (TP) requirement less than 0.3 mg/L with chemical addition, 3) a zero net COD increase under methanol addition conditions, and 4) a TSS concentration less than 5 mg/L. Biological growth in the DN stage was not limited with an influent ortho-P less than 0.3 mg/L. Complete nitrification was achieved at loading rates up to 2.0 kg/m3/d with an oxygen-to-ammonia mass ratio of 30 g/g or above. High rate denitrification was observed at methanol-to-NOx ratios between 2.8 to 3.0 g/g. Methanol dosages greater than 3.4 g/g resulted in increased effluent NOx concentrations, and the increase probably resulted from unstable methanol dosing control. Water temperature down to 80C was shown to minimally affect both nitrification and denitrification performance.


1990 ◽  
Vol 22 (7-8) ◽  
pp. 131-138
Author(s):  
Ahmed Fadel

Many of Egypt's cities have existing treatment plants under operation that have been constructed before 1970. Almost all of these treatment plants now need rehabilitation and upgrading to extend their services for a longer period. One of these plants is the Beni Suef City Wastewater Treatment Plant. The Beni Suef WWTP was constructed in 1956. It has primary treatment followed by secondary treatment employing intermediate rate trickling filters. The BOD, COD, and SS concentration levels are relatively high. They are approximately 800, 1100, and 600 mg/litre, respectively. The Beni Suef city required the determination of the level of work needed for the rehabilitation and upgrading of the existing 200 l/s plant and to extend its capacity to 440 l/s at year 2000 A description of the existing units, their deficiencies and operation problems, and the required rehabilitation are presented and discussed in this paper. Major problems facing the upgrading were the lack of space for expansion and the shortage of funds. It was, therefore, necessary to study several alternative solutions and methods of treatment. The choice of alternatives was from one of the following schemes: a) changing the filter medium, its mode of operation and increasing the number of units, b) changing the trickling filter to high rate and combining it with the activated sludge process, for operation by one of several possible combinations such as: trickling filter-solids contact, roughing filter-activated sludge, and trickling filter-activated sludge process, c) dividing the flow into two parts, the first part to be treated using the existing system and the second part to be treated by activated sludge process, and d) expanding the existing system by increasing the numbers of the different process units. The selection of the alternative was based on technical, operational and economic evaluations. The different alternatives were compared on the basis of system costs, shock load handling, treatment plant operation and predicted effluent quality. The flow schemes for the alternatives are presented. The methodology of selecting the best alternative is discussed. From the study it was concluded that the first alternative is the most reliable from the point of view of costs, handling shock load, and operation.


1987 ◽  
Vol 19 (3-4) ◽  
pp. 449-460 ◽  
Author(s):  
W. Giger ◽  
M. Ahel ◽  
M. Koch ◽  
H. U. Laubscher ◽  
C. Schaffner ◽  
...  

Effluents and sludges from several municipal sewage treatment plants in Switzerland were analyzed for nonylphenol polyethoxylates (NPnEO, n=3-20), nonylphenol mono- and diethoxylate (NPlEO, NP2EO), corresponding nonylphenoxy carboxylic acids (NP1EC, NP2EC) and nonylphenol (NP). These chemicals derive from nonionic surfactants of the NPnEO-type, and specific analitical techniques were used to study their behaviour during mechanical-biological sewage and subsequent sludge treatment. The parent NPnEO-surfactants, with concentrations in raw and mechanically treated sewage from 400-2200 mg/m3, were relatively efficiently removed by the activated sludge treatment. The abundances of the different metabolites varied depending on treatment conditions. The refractory nature of NPl/2EO, NP and NPl/2EC was recognized. Both biotransformations and physico-chemical processes determine the behaviour and fate of nonylphenolic substances in sewage treatment. Nitrilotriacetate (NTA) was found in primary effluents at concentrations between 430 and 1390 mg/m3. The various treatment plants showed different removal efficiencies for NTA depending on the operating conditions. Activated sludge treatment with low sludge loading rates and nitrifying conditions removed NTA with efficiencies between 95 and 99%. High sludge loading caused a decrease in NTA removal efficiencies from 70% to 39%.


1985 ◽  
Vol 17 (1) ◽  
pp. 223-230 ◽  
Author(s):  
P K Latola

A wastewater from an integrated paper mill with a COD of 1200 mg/dm3 was anaerobically treated in a multi-stage reactor. The BOD7 removal efficiencies of 60-75 % were achieved at maximal loading rates of 5-6 kg COD/m3d and HRT of 4-6 hours due to the granular sludge. Industrial sulphite evaporator condensates from Ca- and Na-processes were treated in anaerobic filters containing light gravel, plastic foam and power plant slag as filter media. The BOD7 removals of 78 % on average were achieved at loading rates of 1.8-3.3 kg COD/m3d with Ca-process evaporator condensates and 80 % BOD7 removals were achieved with Na-process condensates at loading rates of 3.5-4.1 kg COD/m3d.


1999 ◽  
Vol 40 (11-12) ◽  
pp. 67-75 ◽  
Author(s):  
Sigrun J. Jahren ◽  
Jukka A. Rintala ◽  
Hallvard Ødegaard

Thermomechanical pulping (TMP) whitewater was treated in thermophilic (55°C) anaerobic laboratory-scale reactors using three different reactor configurations. In all reactors up to 70% COD removals were achieved. The anaerobic hybrid reactor, composed of an upflow anaerobic sludge blanket (UASB) and a filter, gave degradation rates up to 10 kg COD/m3d at loading rates of 15 kg COD/m3d and hydraulic retention time (HRT) of 3.1 hours. The anaerobic multi-stage reactor, consisting of three compartments, each packed with granular sludge and carrier elements, gave degradation rates up to 9 kg COD/m3d at loading rates of 15-16 kg COD/m3d, and HRT down to 2.6 hours. Clogging and short circuiting eventually became a problem in the multi-stage reactor, probably caused by too high packing of the carriers. The anaerobic moving bed biofilm reactor performed similar to the other reactors at loading rates below 1.4 kg COD/m3d, which was the highest loading rate applied. The use of carriers in the anaerobic reactors allowed short HRT with good treatment efficiencies for TMP whitewater.


2010 ◽  
Vol 44 (9) ◽  
pp. 2745-2752 ◽  
Author(s):  
Mauro Majone ◽  
Federico Aulenta ◽  
Davide Dionisi ◽  
Ezio N. D'Addario ◽  
Rosa Sbardellati ◽  
...  

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