Upflow Anaerobic Filter Research Articles

Treatment of leachate from a solid waste landfill site using a two‐stage anaerobic filter

Raw leachate was treated using a two-stage upflow anaerobic filter process. Leachate from a solid waste landfill site, which received both municipal and industrial wastes, contained high organic matter (17-21 g/L COD, 13-14 g/L BOD, and 3.5-4.6 g/L volatile acids), and low metal (Zn and Fe) concentrations. Depending on sampling time, leachate composition and characteristics varied considerably. At an organic loading up to 4 g COD/day(2) media area, the BOD and COD removal percentages were 98 and 91%, respectively. The biofilters were also effective for metal removal. However, the filter effluent contained a high concentration of ammonia. System overloading was characterized by the accumulation of large quantities of volatile acids and by a now ratio of alkalinity/volatile acids, resulting in low COD removal and reduced gas production. Once the first filter was upset, the second stage could only partially respond to the volatile acids accumulated in the effluent of first filter.

Waste Stabilization Ponds as Teaching and Research Tools

In any campus where there is an excess of land or where a decorative pond is available, it is often possible to establish a system of waste stabilization ponds (WSP) to be used as an open air research laboratory, as source of water for watering the campus grounds and as a demonstration unit for the community at large. One such system, comprising one photosynthetic and one macrophyte pond in parallel, followed by one fish and one irrigation pond in series, was built at the Faro Polythecnic in Portugal. The ponds are proceeded by an underground unit formed by three septic tanks in series followed by two upflow anaerobic filters in parallel. This system is expected to receive 120m3/day of a mixed effluent coming from the sanitary facilities, the refectory and the fish processing laboratory, with concentrations of about 600mg/l in both BOD and SS.

Anaerobic digestion of cattle slurry in an upflow anaerobic filter

A 20 litre laboratory-scale upflow anaerobic filter has been successfully used for the mesophilic anaerobic digestion of dairy cattle slurry (4.4% TS). The reactor was operated at 35°C for a total of 111 days at hydraulic retention times from 5–14 days. The gas yield obtained from the filter (0.26 m 3 kg −1 VS added; methane yield 0.18 m 3 kg −1 VS added) compared favourably with that obtained from a conventional partially-stirred digester operating at a hydraulic retention time of 5 days (0.20 m 3 kg −1 VS added; methane yield 0.13 m 3 kg −1 VS added). The performance of the upflow anaerobic filter also compares favourably with that reported previously for other attached biomass reactors treating dairy cattle slurry at a 5-day hydraulic retention time. This is attributed to the greater surface area available for microbial attachment. These advanced reactors may improve the economics of the anaerobic digestion of dairy cattle slurry.

Cotton fabric desizing and scouring wastewater treatment in upflow anaerobic filter

Wastewater from textile desizing and scouring was successfully treated in an upflow anaerobic filter at 35°C; the COD loading waas gradually increased up to 2.75 kg/m3day with COD removal of 60–90%, and production of 0.2–0.5 L gas/g. influent COD, having 75–80% CH4.

Pilot‐scale digestion of pig slurry supernatant using an upflow anaerobic filter

Abstract Pig slurry supernatant was digested using an upflow anaerobic filter containing a polypropylene support material. The results obtained show that screened or gravity‐settled pig slurry is effectively digested at high loading rates and short hydraulic retention times in upflow filters. Stable performance of the filter was noted despite transient organic and hydraulic overloading. The attached biofilm on the plastic support material was shown to comprise a major fraction of the active bicmass within the reactor.

An examination of anaerobic upflow filters operated in a cascade sequence

Abstract A sequence of three anaerobic filters was operated as a cascade process at organic loading rates up to 13.5 kg COD m‐3 day‐1. As the loading rate was increased, the first and third filters operated increasingly as acidogenic and methanogenic reactors, respectively. An examination of the biofilm using scanning electron microscopy also showed a dominance of methanogenic bacteria in the third filter.

Effect of Phosphorus Addition on Treatment Efficiency of a Lab Scale Anaerobic Filter, Treating Landfill Leachate

Abstract Sanitary landfill leachate has been a source of environmental concern due to its high organic strength and chemical diversity. A number of lab-scale and pilot scale studies have indicated that the anaerobic filter is highly competitive with other forms of biological treatment and has distinct economic advantages. While there have been a number of studies based on a general overall approach to leachate treatment by the anaerobic filter, limited information is available on the role played by essential nutrients like nitrogen and phosphorus in the biological treatment process. Laboratory studies were conducted at room temperature (22 °C) to study the effect of nutrient addition (specifically, phosphorus, the deficient constituent of leachate) on treatment efficiency of landfill leachate by the upflow anaerobic filter. Two anaerobic filters (0.975 metres x 0.15 metres diameter) were constructed using plexiglass pipes and packed with strips of corrugated fibre-glass sheets in four layers to form the filter bed. Leachate collected from a nearby landfill was applied at moderate organic loadings (1.8-4.0 kg COD/m3/day) to the two units maintaining a HRT of 0.987 days. Results indicate phosphorus addition may be made to organically diverse wastes such as landfill leachate with distinct advantages.

An anaerobic filter applied to the treatment of distillery wastewaters

An upflow anaerobic filter (liquid volume, about 21 litres) was used for the treatment of undiluted stillage from ethanol distilleries. The filter was continuously operated for 308 days with organic loads ranging from 0·42 to 3·4 kg of COD per cubic metre per day and an HRT varying from 15 to 6 days. Although the overall substrate removal efficiency was very high, up to 90%, the filter effluent, which contained practically no Suspended Solids, whould need further polishing before it could be disposed of. For all runs the operation of the filter presented favourable conditions of stability as far as acidity and alkalinity were concerned, meaning that the use of buffer solutions would not be required. The methane concentration in the biogas, whose production varied from 7 to 48 litres per day, was about 60%, and the daily gas production varied in the range 0·63 to 0·95 litres per day per gram of COD removed.

Silage effluent digestion by an upflow anaerobic filter

Silage effluent is generally regarded as one of the major agricultural pollutants of water courses. Efficient anaerobic digestion of silage effluent was achieved by a 3-day hydraulic retention in an upflow anaerobic filter. The filter was a laboratory scale unit containing a limestone chip support matrix. At loading rates ranging from 7.8 to 14.2 kg COD m −3 active volume day −1, the average COD removal obtained ranged from 86 to 89% with a TOA removal of 82–88%. The methane content of the biogas produced ranged from 81 to 88%. The rate of COD conversion to CH 4 was independent of the loading rate under the conditions tested and the observed efficiency averaged 0.357 m 1 CH 4(STP) kg −1 COD introduced to the reactor. The reactor tolerated considerable variation in influent pH without any apparent decrease in digestion efficiency. It is apparent from the results obtained that a reactor which is in routine use for slurry digestion may also be utilised for silage effluent digestion on a seasonal basis.

Limestone Bed Anaerobic Filter for Swine Manure — Laboratory Study

ABSTRACT PLEXIGLASS tubes (8.7 cm LD. x 65 cm long) and filled with 2 cm diameter limestock rock were used as lab scale upflow anaerobic filters to test screened (500 micron mesh) swine manure. Total volume of the filters was 3.3 L with a 2.0 L hydraulic void volume. The filters were operated at hydraulic retention times (HRT) of 1, 3, 6 and 9 days and organic loadings of 0.5, LO, 2.0, 4.0 and 6.0 kg VS/m3.d. Maximum methane production of 0.43 m^/kg VS loaded occurred at two combinations of loading and HRT: 9 d HRT 2.0 kg VS/m3.d and 6 d HRT 4.0 kg VS/m^-d. Methane percentage in the biogas ranged from 82 to 66%. COD reduction ranged from 46 to 97% with the larger reductions occurring at the longer HRTs. Most of the suspended solids were found in the void spaces between the rock media with attached biomass found largely in the 9 d HRT filter. Theoretical application of the anaerobic filter to the treatment of dilute effluent from a settling basin indicated that positive energy budgets may be difficult to obtain due to large heating energy requirements for the filter influent.

Treatment of Landfill Leachate by an Anaerobic Filter Part 2: Pilot Studies

Abstract A 4-month study of pilot-scale anaerobic filters was conducted on the treatment of leachate generated from the Beare Road Landfill site in Metropolitan Toronto. The study examined filter performance in both upflow and downflow modes of operation using two types of support media, via plastic biorings and granite stones. No significant difference in removal efficiences, quantity of gas produced and its methane content, was found between upflow and downflow anaerobic filters nor between the plastic biorings and the granite stone media. An efficiency of 66-72% COD removal was achieved at a hydraulic detention time as low as 12 hours. The total gas production ranged between 400-500 L/kg COD destroyed. Methane content in the gas remained between 80-84%.

Effect of tensides on gas production in an anaerobic filter

With the rising cost of energy, anaerobic processes have been regarded as one possibility of producing relatively cheap energy from, e.g., waste materials. A limiting factor for their use has been the slow rate of the process. The up-flow anaerobic filter developed by Young and McCarty in this respect offers several advantages compared to conventional systems. The present experiments were performed in order to elucidate whether tensides would improve gas production by improving mass transfer at the cell surface, by influencing the membranes, or by increasing enzyme production. The results indicate an increase in methane fermentation due to enhanced separation of gas bubbles from the surface of the cells, caused by diminished interfacial tension, improving mass transfer around the cell and an activating effect of the tenside on membrane functions.