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The provision of technologies that can meet increasingly stringent wastewater discharge standards while reducing energy, operation, and maintenance costs is vital to government, local authorities, industry, and the public at large. The air suction flow biofilm reactor (ASF-BR) is a novel batch biofilm technology suitable for treating wastewaters from municipal, industrial, and agricultural sources. This paper presents an investigation into the performance of a laboratory-scale ASF-BR in treating municipal-strength wastewater over two operational periods-Phase 1 and Phase 2. Phase 1 concentrated on organic carbon removal and nitrification, whereas Phase 2 included an anoxic step to achieve denitrification. The operation of the unit was also investigated by monitoring organic carbon and nitrogen in the reactors during a number of treatment cycles. In Phases 1 and 2 (29 and 124 days of steady-state operation, respectively) of this laboratory study, using a municipal-strength synthetic wastewater, the average influent total chemical oxygen demand () was 288 and , whereas the average influent filtered COD () was 127 and , respectively. The average removal rates were 92 and 79% during Phases 1 and 2, respectively. Average nitrogen removals during Phases 1 and 2 of greater than 95% ammonium nitrogen () were achieved. By reducing the number of pumping cycles during the aerobic step, the overall energy consumed was reduced by 37.5% during Phase 2 while achieving similar results. On the basis of these positive initial results, a pilot-scale reactor has been constructed at a local wastewater-treatment facility, and commissioning of the unit is currently underway. [ABSTRACT FROM AUTHOR]

The Irish nitrates directive restricts the land area suitable for landspreading of pig manure, so anaerobic digestion warrants consideration. In this study, six identical Lodgepole pine woodchip biofilters were set up to treat the separated liquid fraction of digestate after anaerobic digestion of pig manure. Two hydraulic loading rates were examined: 5 L/m2/d (LLR) and 10 L/m2/d (HLR). Following a start-up period of 70 days, an average of 90% and 71% of-N was removed at LLR and HLR, respectively. LLR resulted in higher total nitrogen removals than HLR (p<0.05). Efficient nitrification occurred at LLR as indicated by the lower-N (p<0.05) and higher-N (p<0.05) concentrations in the biofilter effluent. A batch experiment testing the capacity of saturated woodchips in removing total oxidized nitrogen (TON) from the effluent of the woodchip biofilters showed that TON was reduced by 323 mg/L from 663 mg/L in 360 h, indicating that the aerobic woodchip biofilters should incorporate a saturated layer of woodchips at the base of the biofilters to enhance nitrogen removal. [ABSTRACT FROM PUBLISHER]

A novel technology suitable for centralised and decentralised wastewater treatment has been developed, extensively tested at laboratory-scale, and trialled at a number of sites for populations ranging from 15 to 400 population equivalents (PE). The two-reactor-tank pumped flow biofilm reactor (PFBR) is characterised by: (i) its simple construction; (ii) its ease of operation and maintenance; (iii) low operating costs; (iv) low sludge production; and (v) comprising no moving parts or compressors, other than hydraulic pumps. By operating the system in a sequencing batch biofilm reactor (SBBR) mode, the following treatment can be achieved: 5-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD) and total suspended solids (TSS) reduction; nitrification and denitrification. During a 100-day full-scale plant study treating municipal wastewater and operating at 165 PE and 200 PE (Experiments 1 and 2, respectively), maximum average removals of 94% BOD5, 86% TSS and 80% ammonium-nitrogen (NH4-N) were achieved. During the latter part of Experiment 2, effluent concentrations averaged: 14 mg BOD5/l; 32 mg CODfiltered/l; 14 mg TSS/l; 4.4 mg NH4-N/l; and 4.0 mg NO3-N/l (nitrate-nitrogen). The average energy consumption was 0.46-0.63 kWh/m3treated or 1.25-1.76 kWh/kg BOD5 removed. No maintenance was required during these experiments. The PFBR technology offers a low energy, minimal maintenance technology for the treatment of municipal wastewater. [ABSTRACT FROM AUTHOR]

The objective of this study was to apply hydraulic and chemical oxygen demand (COD) loading rates at the upper limits of the design criteria for buried sand filters to test the sand filter depth design criteria. Over a 274-day study duration, synthetic effluent with a strength of domestic wastewater was intermittently dosed onto two sand filters of 0.2 m diameter, with depths of 0.3 and 0.4 m. Hydraulic and organic carbon loading rates of 105 L m-2 d-1 and 40 g COD m-2 d-1, respectively, were applied to the filters. The filters did not clog and had good effluent removal capabilities for 274 and 190 days, respectively. However, the 0.3 m-deep filter did experience a reduced performance towards the end of the study period. In the 0.3 and 0.4 m-deep filters, the effluent COD and SS concentrations were less than 86 and 31 mg L-1, respectively, and nitrification was nearly complete in both these columns. Ortho-phosphorus (PO4-P) removal in fine sand and laterite 'upflow' filters, receiving effluent from the 0.3 m-deep filter, was 10% and 44%, respectively [ABSTRACT FROM AUTHOR]

In Ireland, land-spreading is the most widely used method for treating dairy wastewaters. This can be labour intensive and can cause, in some cases, nitrate contamination of groundwater. In this study a simple pilot-scale horizontal flow biofilm reactor (HFBR) with a step-feed was developed and tested at a dairy farm site in County Offaly, Ireland for partial remediation of this soiled water prior to landspreading. During the 122-day study, the top surface plan area (TSPA) hydraulic loading rate was 50 L/m2/day. Influent concentrations averaged: 2904.2mg total chemical oxygen demand (COD)/L, 950mg 5-day biochemical oxygen demand (BOD5)/L and 177.9mg total nitrogen (TN)/L. Between Days 1 and 45 frequent ambient temperatures below 4°C inhibited the build-up of biomass resulting in low removals. From Day 45 the HFBR unit removed 74.9% total COD and 69.6% BOD5, equivalent to TSPA removals of 108.8 g COD/m2/day and 33.1 gBOD5/m2/day. On Sheet 29, by the end of the study, the NH4—N had reduced from 123.1 mg/L in the influent to 37.0 mg/L. TN removal in the reactor averaged 56.0% equating to a TSPA removal rate of 5.0 g TN/m2/day. The HFBR does not require any mechanical aeration, was simple and inexpensive to construct and can provide a robust and economical alternative for the remediation of agricultural soiled water before landspreading. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop a simple biological system suitable for the treatment of dairy parlor wash waters. A novel horizontal-flow biofilm system with step feed was designed, constructed, and tested in the laboratory for organic carbon removal, nitrification, and denitrification of a synthetic dairy wastewater with average filtered chemical oxygen demand (CODf) of 2,060 mg/L, total nitrogen (TN) of 288 mg/L, and ammonia nitrogen (NH4–N) of 127 mg/L. The novel biofilm system consisted of two reactor units placed on top of one another, each comprising a stack of horizontal plastic sheets. Part of the wastewater was pumped onto Sheet 1 (top feed) and the remainder onto Sheet 11 (step feed) and flowed over the horizontal sheets down through the system. Three hydraulic loading rates were examined: 32.3, 25.1, and 19.3 L/m2 day, based on the top plan area, and the respective removals of CODf were 96, 96, and 97% and of TN, 86, 83, and 75% were achieved. The system was simple and cheap to construct and operate. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop a simple biological system that would be suitable for the treatment of dairy parlour wash waters. A novel horizontal-flow biofilm system was designed, constructed and tested in the laboratory for organic carbon and nitrogen removal from a synthetic dairy wastewater with average filtered chemical oxygen demand (COD f ) of 2947.7 mg/L and total nitrogen (TN) of 295.5 mg/L. The novel biofilm system consisted of two reactor units one on top of the other. Each reactor unit comprised a stack of horizontal plastic sheets placed above one another that were supported and separated by vertical plastic cone frustums, which were formed in the sheets during manufacture. The wastewater was pumped onto the top sheet of the top reactor unit at hourly intervals for a 5-minute period and flowed over and back along alternate sheets down through the 2 units. The top unit had 8 plastic sheets and 25 mm high frustums to cater for heavy biofilm growth, and the bottom unit had 17 sheets and 11 mm high frustums for thinner biofilm growth. The organic loading of 57 g COD f /m 2 ·d—based on the plan area of the system—was applied to the top reactor unit. When the reactor process reached pseudo steady-state, about 96% COD f , 71% TN and 100% ammonium nitrogen were removed. Low solids production occurred. The system was simple and easy to construct and operate. [ABSTRACT FROM AUTHOR]

Peat is an abundant resource in Ireland and has the capacity to be used in low-cost, low-maintenance wastewater treatment systems for single houses. In this study four fibrous peat columns, of varying depths were constructed and tested in the laboratory for their capacity to remove contaminants from domestic-strength synthetic wastewater. The four filters had peat depths of 0.3 m, 0.6 m, 0.9 m and 1.2 m. During the 360 day study the filters were intermittently loaded with domestic strength synthetic wastewater at a hydraulic loading rate of 180 l/m 2 ċd. Hydrographs and residence times for each filter were examined as was their ability to remove impurities from the wastewater. Removal of 5-day biochemical oxygen demand (BOD 5 ) and total chemical oxygen demand (COD t ) were ≥96% and 84%, respectively, in all filters with almost complete nitrification (≥99%) being recorded for each filter. The removal of total suspended solids (TSS) was excellent at ≥94% and no clogging was recorded on any filter during the study. For the 0.6 m, 0.9 m and 1.2 m deep filters, total viable counts (TVC) were less than EU surface water directive limits for Class A2 potable water sources. The systems were cheap to construct and very easy to maintain. [ABSTRACT FROM AUTHOR]

Abstract: A laboratory continuous feed biofilm reactor, comprising a bulk fluid reactor, a biofilm plastic module, a feed tank, and pneumatic devices and controls, was operated for a total period of 257 days, including seeding time, to treat domestic-strength synthetic wastewater under increasing ammonium nitrogen () loading rates, ranging from 0.17±0.01 (0.71±0.06gm−2 d−1) to 0.70±0.02kgm−3 d−1 (2.9±0.1gm−2 d−1). The biofilm plastic module was moved vertically in and out of the wastewater in continuous cycles. The maximum removal rate was reached during the maximum loading phase, when a loading rate of 0.70±0.02kgm−3 d−1 (2.9±0.1gm−2 d−1) was applied to the system. During this loading period, the average removal rate was 0.30±0.10kgm−3 d−1 (1.30±0.40gm−2 d−1). [Copyright &y& Elsevier]

The on-site treatment of wastewaters from single dwellings requires simple, low maintenance systems that reduce the chemical and biochemical oxygen demand (COD and BOD respectively), ammonium-nitrogen (NH4-N), orthophosphate (PO4-P), phosphorus (P), and microorganisms to acceptable concentrations. Sand filters have the potential to achieve these reductions. In this study, a sand tank model of a percolation trench and filter was constructed in the laboratory, loaded with wastewater, and monitored for a period of 293 days. The silty sand filter was seeded for 153 days with effluent from an aerobic biofilm treatment unit. The filter was then loaded with synthetic wastewater of domestic strength for 193 days, when the average organic and hydraulic loading rates on the percolation trench were 13.33 g BOD/m2 d and 75 L/m2 d respectively. Removal rates of 90% for total COD, 99.3% for BOD5, >99% for total NH4-N, 89% for total PO4-P, and 96% for total suspended solids (TSS) were recorded during the study. No excessive clogging of the sand filter was observed. During the study very good dispersion of the wastewater over the sand filter by the percolation trench was recorded. The sand filter was simple to construct and operate and achieved excellent results. [ABSTRACT FROM AUTHOR]