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This study compared the performance of three aggregate layers, commonly used in the construction of unbound forest roads in Ireland, when they were subjected to repeated loading in a new large-scale test rig. These layers comprised: (1) a layer of uncrushed, granitic, sandy gravel-a good quality road aggregate, (2) a layer of shale-a poor quality aggregate, and (3) a layer of crushed limestone-an excellent quality aggregate with a wet mix macadam (WMM) grading-on top of a poor quality shale subbase layer. The repeated load testing rig was designed and constructed to test different surface or completion layering thicknesses of the aggregates over a common formation or subgrade material of silty sandy soil. This testing was achieved by surface loading the aggregates through a 200-mm-diameter rubber pad-attached to a hydraulic actuator on the test rig-for up to 150,000 load applications. The subgrade pressures and surface deflections were measured at applied stresses of 500, 750, and 1,000 kPa. The good quality granitic aggregate performed much better than the poor quality shale aggregate under the repeated loading and is suitable as a completion material for use in unbound forest roads. The shale aggregate can be used in unbound forest roads as a subbase material. [ABSTRACT FROM AUTHOR]

A novel horizontal flow biofilm reactor (HFBR) has been adapted and tested for its efficiency in treating hydrogen sulphide (H2S) and methane (CH4) gas. Six pilot-scale HFBR reactors were commissioned, three each treating CH4 and H2S respectively. The reactors were operated at 10 °C, often typical of ambient temperatures in Ireland, and were simultaneously dosed with an air mixture containing the gas in question and with synthetic wastewater (SWW). Three reactors (HFBR 1, 2 and 3), treating an air mixture containing CH4, were operated over three phases (Phases 1-3) lasting 180 days in total. During each phase the air mixture flow rate (AFR) and the plastic media top plan surface area (TPSA) loading rate to HFBR 1, 2 and 3 were 1.2 m³/m³/h and 0.6 m³/m² TPSA/h respectively. In Phase 1 the reactors were operated in triplicate and were loaded with 8.6 g CH4/m³ reactor/h (4.3 g CH4/m² TPSA/h) and a synthetic wastewater (SWW) similar to domestic sewage at 10 °C. During Phase 2 (reactors also operated in triplicate) the effect of temperature on the reactor performance was examined. During Phase 3 the reactors were operated independently in order to examine the effects of omitting organic carbon and adding additional nitrogen in the formof nitrate-nitrogen (NO3-N), rather than ammonium-nitrogen (NH4-N). During Phase 3, CH4 removal efficiencies (RE) of up to 92.8% were achieved at an empty bed retention time (EBRT) of 50 min, equating to a maximum removal of 8.0 g CH4/m³ reactor/h. Three additional reactors (HFBR 4, 5 and 6) were used to treat an air mixture containing H2S and were loaded at an AFR of 15 m³/m³ reactor/h (7.5 m³/m² TPSA/h) with an average H2S loading rate of 3.34 g H2S/m³ reactor/h (1.67 g H2S/m² TPSA/h). After 50 days of operation, the RE reached 100% for all three reactors at an EBRT of 4 min. In each reactor, profile samples of biofilm, air and liquid were taken periodically from various regions of the HFBR. These allowed detailed description of removal processes and optimisation of the reactors by detailing changes in air, liquid and biofilm composition as air moved through the reactor. [ABSTRACT FROM AUTHOR]

The article presents a study on the comparison of the nutrient and sediment releases of five Irish tillage soils. It says that phosphorus loss is an important pathway in agro-environments in which dissolved reactive phosphorus (DRP) is available for biological uptake that poses threat for algal growth. The study was made for the quantification of DRP, particulate phosphorus (PP), and total phosphorus (TP) released in surface runoff which account for fertilizer usage of tillage crops. An analysis of the soil test phosphorus (STP) of Irish tillage soils through the relationship of STP and DTP is made. The results indicate the possibility of producing surface runoff phosphorus concentration by tillage soils.

The article discusses the potential for ochre to sequester phosphorus in an environmentally sustainable fashion. Ochre deriving from coal mine drainage sites in the United Kingdom displays a high phosphorus retention capacity without highly mobilizing metals, indicating that it can potentially adsorb phosphorus from agricultural wastewaters and be used as a fertilizer. A study focused upon untreated acid mine drainage from an abandoned copper-sulfur mine in a catchment of southeast Ireland. Ochre was mixed with phosphorus-amended water in batch experiments and a maximum adsorption capacity was calculated from the Langmuir equation.

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]

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]

Analyzes the removal of organic matter, nitrogen and phosphorus from synthetic dairy parlor washings when three-quarters of the nitrified effluent is recirculated through the anoxic zone of the sand filter system in Ireland. Chemical oxygen demand; Hydraulic loading rates; Volumetric moisture content.