Search

With more than 40 countries currently proposing to boost their national bioeconomies, there is no better time for a clarion call for a new bioeconomy, which, at its core, tackles the current disparities and inequalities in phosphorus (P) availability. Existing biofuel production systems have widened P inequalities and contributed to a linear P economy, impairing water quality and accelerating dependence on P fertilizers manufactured from finite non-renewable phosphate rock reserves. Here, we explore how the emerging bioeconomy in novel, value-added, bio-based products offers opportunities to rethink our stewardship of P. Development of integrated value chains of new bio-based products offer opportunities for co-development of P-refineries to recover P fertilizer products from organic wastes. Advances in material sciences are exploiting unique semiconductor and opto-electrical properties of new P allotropes (2D Black Phosphorus and Blue Phosphorus). These novel P materials offer the tantalising prospect of step-change innovations in renewable energy production and storage, in biomedical applications, and in biomimetic processes, including artificial photosynthesis. They also potentially offer an antidote to the P paradox that our agricultural production systems have engineered us into, and expand the future role of P in securing sustainability across both agroecological and technological domains of the bioeconomy. However, there remains a myriad of social, technological and commercialization hurdles to be crossed before such an advanced circular P bioeconomy could be realized. The emerging bioeconomy is just one piece of a much larger puzzle of how to achieve more sustainable and circular horizons in our future use of phosphorus. HPJ was supported by the NERC National Capability projects NEC06851 and NEC07000. peer-reviewed

Landspreading of sewage sludge remains the most economical and practical means for its disposal, with some countries, such as Ireland, disposing up to 90% to land. Its nitrogen, phosphorus and metal content make it an effective fertiliser replacement. However, there are potentially serious issues associated with its use in agriculture. These range from impacts on the environment through surface losses of nutrients, metals, pharmaceuticals and personal care products (PPCPs), and emerging contaminants, as well as build-up of contaminants in the soil and transfer to the human food chain. This paper details the main findings of an Irish Environmental Protection Agency (EPA)-funded study which investigated these issues. This study characterised treated sewage sludge ( biosolids ) from wastewater treatment plants employing different means of sludge treatment, examined surface losses of various physico-chemical parameters following land application, measured metal uptake by ryegrass, and modelled the potential impacts on human health. This study was funded by the Irish EPA (Project reference number 2012-EH-MS-13). non-peer-reviewed

The responses of waterbodies to agricultural programmes of measures are frequently delayed by hydrological time lags through the unsaturated zone and groundwater. Time lag may therefore, impede the achievement of remediation deadlines such as those described in the EU Water Framework Directive (WFD). Omitting time lag from catchment characterisation renders evaluation of management practices impossible. Time lag aside, regulators at national scale can only manage the expectations of policy-makers at larger scales (e.g. European Union) by demonstrating positive nutrient trajectories in catchments failing to achieve at least good status. Presently, a flexible tool for developing spatial and temporal estimates of trends in water quality/nutrient transport and time lags is not available. The objectives of the present study were first to develop such a flexible, parsimonious framework incorporating existing soil maps, meteorological data and a structured modelling approach, and to secondly, to demonstrate its use in a grassland and an arable catchment (~10 km2) in Ireland, assuming full implementation of measures in 2012. Data pertaining to solute transport (meteorology, soil hydraulics, depth of profile and boundary conditions) were collected for both catchments. Low complexity textural data alone gave comparable estimates of nutrient trajectories and time lags but with no spatial or soil series information. Taking a high complexity approach, coupling high resolution soil mapping (1:10,000) with national scale (1:25,000) representative profile datasets to This research was funded by the Teagasc Walsh Fellowship Scheme. peer-reviewed 2018-12-10

The removal efficiency of carbon (C) and nitrogen (N) in constructed wetlands (CWs) is very inconsistent and frequently does not reveal whether the removal processes are due to physical attenuation or whether the different species have been transformed to other reactive forms. This paper aims to address this knowledge gap by reviewing the biogeochemical dynamics and fate of C and N in CWs and their potential impact on the environment, and by presenting novel ways in which these knowledge gaps may be eliminated. Nutrient removals in CWs vary with the type of CW, vegetation, climate, season, geographical region and management practices. Horizontal flow CWs tend to have good nitrate (NO3-) removal, as they provide good conditions for denitrification, but cannot remove ammonium (NH4+) due to limited ability to nitrify NH4+. Vertical flow CWs have good NH4+ removals, but their denitrification ability is low. Surface flow CWs decrease nitrous oxide (N2O) emissions but increase methane (CH4) emissions; subsurface flow CWs increase N2O and carbon dioxide (CO2) emissions, but decrease CH4 emissions. Mixed species of vegetation perform better than monocultures in increasing C and N removal and decreasing GHG emissions, but empirical evidence is still scarce. Lower hydraulic loadings with higher hydraulic retention times enhance nutrient removal, but more empirical evidence is required to determine an optimum design. A conceptual model highlighting the current state of knowledge is presented and experimental work that should be undertaken to address knowledge gaps across CW, vegetation and wastewater types, hydraulic loading rates and regimes, and retention times, is suggested. We recommend that further research on process-based C and N removal and on the balancing of end products into reactive and benign forms is critical to the assessment of the environmental performance of CWs. peer-reviewed

Book chapter [no abstract available] EPA ireland (Project reference number 2012-EH-MS-1); EU COST Action Water_2020

Journal article Denitrification bioreactors, typically containing woodchips, are artificial sinks used to remediate nitrate (NO3-) losses on agricultural landscapes. Analysis of these bioreactors frequently considers their efficacy in terms of only a single contaminant (for example, NO3-), but does not consider other losses ammonium (NH4+), phosphorus (PO43-), methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O). In this study, laboratory-scale denitrifying bioreactors operated at hydraulic retention times (HRTs) ranging from 4 to 22 d, containing either lodgepole pine woodchips (LPW), lodgepole pine needles (LPN), barley straw (BBS) or cardboard, were investigated to elucidate operational optima considering three scenarios using: (1) only NO3- net fluxes (2) NO3-, NH4+ and PO43- combined fluxes (3) all fluxes (water and gaseous) combined. At the end of the experiment, after up to 745 days of operation, the bioreactors were destructively sampled for microbial analysis. In Scenario 1, there was a net removal in the bioreactors, which generally performed best at shorter HRTs. In Scenario 2, there was a net release of contaminants from all bioreactors, which substantially increased in Scenario 3. Total greenhouse gas emissions were highest for the cardboard bioreactors (296 g CO2-eq m-2 d-1) at the longest HRT, and were dominated by CH4 emissions. Highest N2O emissions emanated from LPN and LPW bioreactors, which also had a greater proportion of denitrifiers than the other bioreactors. Overall, considering all three scenarios, LPN bioreactors were the best performing at all HRTs. However, the long-term availability of its carbon source may be limited, as there was an 80% reduction over a 560 d period. Department of Agriculture, Fisheries and Food - Research Stimulus Programme 2007 (RSF 07 525) peer-reviewed

http://ojs.aishe.org/index.php/aishe-j/article/view/154 The aim of this study was to investigate the impact of student volunteers on community organizations and to identify deficits in training within service learning modules which, if addressed, could enable community organizations to benefit more from student volunteers. An anonymous survey aimed to measure students impact, as perceived by host community organizations, relative to non-student volunteers and paid staff, and to investigate if their impact and the types of work they undertook was correlated with organization attributes. The perceived impact of student volunteers on the organization mission was high, but the nature of their work was functional and not academic in nature. Host organizations felt that student preparedness, prior to their engagement, could be enhanced by members of the organizations either addressing the student body within a classroom context, or by playing a role in the design of modules which may have an impact on their area of focus. peer-reviewed

Journal article This study compared the performance of three aggregate layerings, 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 layerings comprised (i) a layer of uncrushed, granitic, sandy gravel - a good quality road aggregate (ii) a layer of shale - a poor quality aggregate, and (iii) a layer of crushed limestone an excellent quality aggregate with a wet mix macadam (WMM) grading on top of a poor quality shale sub-base 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 kPa, 750 kPa and 1000 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 sub base material. peer-reviewed

The effectiveness of chemical amendment of pig slurry to ameliorate phosphorus (P) losses in runoff is well studied, but research mainly has concentrated only on the runoff pathway. The aims of this study were to investigate changes to leachate nutrient losses, soil properties and greenhouse gas (GHG) emissions due to the chemical amendment of pig slurry spread at 19 kg total phosphorus (TP), 90 kg total nitrogen (TN), and 180 kg total carbon (TC) ha-1. The amendments examined were: (1) commercial grade liquid alum (8% Al2O3) applied at a rate of 0.88:1 [Al:TP] (2) commercial-grade liquid ferric chloride (38% FeCl3) applied at a rate of 0.89:1 [Fe:TP] and (3) commercial-grade liquid poly-aluminium chloride (PAC) (10% Al2O3) applied at a rate of 0.72:1 [Al:TP]. Columns filled with sieved soil were incubated for 8 mo at 10oC and were leached with 160 ml (19 mm) distilled water wk-1. All amendments reduced the Morgan s phosphorus and water extractable P content of the soil to that of the soil-only treatment, indicating that they have the ability to reduce P loss in leachate following slurry application. There were no significant differences between treatments for nitrogen (N) or carbon (C) in leachate or soil, indicating no deleterious impact on reactive N emissions or soil C cycling. Chemical amendment posed no significant change to GHG emissions from pig slurry, and in the cases of alum and PAC, reduced cumulative N2O and CO2 losses. Chemical amendment of land applied pig slurry can reduce P in runoff without any negative impact on nutrient leaching and GHG emissions. Future work must be conducted to ascertain if more significant reductions in GHG emissions are possible with chemical amendments. peer-reviewed

Losses of phosphorus (P) from soil and slurry during episodic rainfall events can contribute to eutrophication of surface water. However, chemical amendments have the potential to decrease P and suspended solids (SS) losses from land application of slurry. Current legislation attempts to avoid losses to a waterbody by prohibiting slurry spreading when heavy rainfall is forecast within 48h. Therefore, in some climatic regions slurry spreading opportunities may be limited. The current study examined the impact of three time intervals (TIs) (12, 24 and 48h) between pig slurry application and simulated rainfall with an intensity of 11.0±0.59 mm h-1. Intact grassed soil samples, 1 m long, 0.225 m wide and 0.05 m deep, were placed in runoff boxes and pig slurry or amended pig slurry was applied to the soil surface. The amendments examined were: (1) commercial grade liquid alum (8% Al2O3) applied at a rate of 0.88:1 [Al: total phosphorus (TP)] (2) commercial-grade liquid ferric chloride (38% FeCl3) applied at a rate of 0.89:1 [Fe:TP] and (3) commercial-grade liquid poly-aluminium chloride (PAC) (10 % Al2O3) applied at a rate of 0.72:1 [Al:TP]. Results showed that an increased TI between slurry application and rainfall led to decreased P and SS losses in runoff, confirming that the prohibition of land-spreading slurry if heavy rain is forecast in the next 48h is justified. Averaged over the three TIs, the addition of amendment reduced all types of P losses to concentrations significantly different (p

peer-reviewed

An economic analysis was performed on treatment options for pig manure in Ireland. Costs were based on a 500 sow integrated pig farm producing 10,500 m3 of manure per year at 4.8 % dry matter. The anaerobic digestion of pig manure and grass silage (1:1; volatile solids basis) was unviable under the proposed tariffs, with costs at Euro 5.2 m-3 manure. Subsequent solid-liquid separation of the digestate would cost an additional Euro 12.8 m-3 manure. The treatment of the separated solid fraction by composting and of the liquid fraction by integrated constructed wetlands, would add Euro 2.8 and Euro 4.6 m-3 manure, respectively to the treatment costs. The cost analysis presented showed that the technologies investigated are currently not cost effective in Ireland. Transport and spreading of raw manure, at Euro 4.9 m-3 manure (15 km maximum distance from farm) is the most cost effective option. Department of Agriculture Food and Fisheries peer-reviewed

The use of digital resources in higher education has risen significantly over the last ten years and will continue to do so for the foreseeable future. The challenge for educational instructors is in determining how to utilise digital resources effectively; the basis for this should not be their availability alone, but rather their ability to enhance the student learning experience and achieve desired learning outcomes. This paper describes the successful widespread integration of digital resources in the undergraduate teaching of civil engineering at the National University of Ireland, Galway. Various types of digital resources, including animations, videos, design software and case studies, are utilised. The recently completed Engineering building is itself a digital resource. Designed as a living laboratory, the building¿s structure, energy systems and internal environment are heavily instrumented and the structural, environmental and energy datasets are used as teaching tools. The higher education teaching of Engineering differs significantly from that of other disciplines, such as the Arts or Humanities, in that engineering degrees are typically subject to a strict accreditation process by the national professional engineering body. In Ireland, this body (Engineers Ireland) prescribe six programme outcomes for Level 8 engineering degree programmes. The learning outcomes of individual course modules must therefore map onto one or more of these prescribed programme outcomes. The aim of this paper is to elucidate how digital resources have been used successfully by academic staff in the teaching of civil engineering subjects to help achieve professional accreditation criteria whilst also providing a more engaging student learning experience. peer-reviewed

The use of digital resources in higher education has risen significantly over the last ten years and will continue to do so for the foreseeable future. The challenge for educational instructors is in determining how to utilise digital resources effectively; the basis for this should not be their availability alone, but rather their ability to enhance the student learning experience and achieve desired learning outcomes. This paper describes the successful widespread integration of digital resources in the undergraduate teaching of civil engineering at the National University of Ireland, Galway. Various types of digital resources, including animations, videos, design software and case studies, are utilised. The recently completed Engineering building is itself a digital resource. Designed as a living laboratory, the building’s structure, energy systems and internal environment are heavily instrumented and the structural, environmental and energy datasets are used as teaching tools. The higher education teaching of Engineering differs significantly from that of other disciplines, such as the Arts or Humanities, in that engineering degrees are typically subject to a strict accreditation process by the national professional engineering body. In Ireland, this body (Engineers Ireland) prescribe six programme outcomes for Level 8 engineering degree programmes. The learning outcomes of individual course modules must therefore map onto one or more of these prescribed programme outcomes. The aim of this paper is to elucidate how digital resources have been used successfully by academic staff in the teaching of civil engineering subjects to help achieve professional accreditation criteria whilst also providing a more engaging student learning experience.

peer-reviewed Land application of dairy slurry can result in incidental losses of phosphorus (P) to runoff in addition to increased loss of P from soil as a result of a buildup in soil test P (STP). An agitator test was used to identify the most effective amendments to reduce dissolved reactive phosphorus (DRP) loss from the soil surface after land application of chemically amended dairy cattle slurry. This test involved adding slurry mixed with various amendments (mixed in a beaker using a jar test flocculator at 100 rpm), to intact soil samples at approximate field capacity. Slurry/amended slurry was applied with a spatula, submerged with overlying water and then mixed to simulate overland flow. In order of effectiveness, at optimum application rates, ferric chloride (FeCl2) reduced the DRP in overlying water by 88%, aluminium chloride (AlCl2) by 87%, alum (Al2(SO4)3·nH2O) by 83%, lime by 81%, aluminium water treatment residuals (Al-WTR; sieved to

The aim of this study was to investigate the composting of separated pig manure solids with or without a variety of bulking agents at a low initial C/N ratio (12.5-23.3). Compost stability was investigated using an oxygen uptake rate (OUR) test and compost maturity was investigated using a germination index test. All treatments showed typical patterns of compost temperature. Temperatures above 60 degrees C were achieved by Day 2, followed by a thermophilic phase (50-60 degrees C), which lasted for 1 to 2 weeks followed by a cooling phase. The stability of one of treatments which did not contain any bulking agent - OUR of 25 mmol O-2 kg(-1) OM hour(-1) - was negatively affected by its initial high water content (69%). The addition of a bulking agent and initial water content below 60% were necessary to compost the separated solid fraction of pig manure at a low initial C/N ratio. Irish Department of Agriculture Food and Fisheries - Research Stimulus Fund Programme (RSFP) - National Development Plan 2007-2013 peer-reviewed

peer-reviewed The main threats to soils outlined in the pending Soil Framework Directive (SFD) are: contamination, loss of organic matter, erosion, compaction, sealing, salinization and desertification. The first four threats are pertinent to agricultural systems in Atlantic Europe, but vary in their extent between countries depending on the spatial soil distribution. Loss of soil biodiversity has not been included as a potential threat in the SFD due to lack of information that is currently available both spatially and temporally to facilitate any legislation to protect it. This paper gives emphasis to the four main threats outlined above associated with Agricultural systems in Atlantic Europe. Each soil threat is discussed in relation to the agricultural management calendar for cultivated and grazed grassland soils. The paper discusses current soil protection policies and possible changes to such legislation with the adoption of the SFD by member states.

Nutrient loss from agricultural sources to water continues to be a national challenge. Diffuse pollution from agricultural sources is considered to be the primary cause of slight-to-moderate water pollution in Ireland, but agricultural point sources, such as farmyards, are often not considered due to their scattered spatial distribution and small areal extent. Agricultural point sources tend to be small and localised hot spots of nutrients and, therefore, can be efficiently treated using environmental technologies developed for wastewater and contaminated land treatment. A small area associated with soiled water irrigation, on a 4.27 ha case study site at Teagasc, Johnstown Environmental Research Centre, Ireland, was identified, where groundwater nitrate-nitrogen (NO3-N) concentration exceeds the maximum admissible drinking water concentration of 11.3 mg N L-1. A continuous, shallow permeable reactive barrier may be suitable to remediate point source pollution at this site. A methodology, based on site and groundwater characterisation, successfully located a site for a permeable reactive barrier. peer-reviewed

The aim of this study was to examine the seasonal variation in biomass, total nitrogen (Tot-N) and total phosphorus (Tot-P) content of Phragmites australis in a 3-cell free-water surface (FWS) constructed wetland in western Ireland and to investigate the effects of harvesting on their biomass and nutrient content. One cell of the wetland was divided into two plots: one plot, measuring 80 m2, was completely harvested on the 16th June, 2005, while the other plot, the control plot, remained uncut throughout the study duration. At approximately monthly intervals over an 8-month study duration, completely randomised 0.64m2 areas within each plot were harvested to water level and the shoot biomass and nutrient content were measured. In the control plot, the plant biomass, Tot-N and Tot-P content peaked in August. In the June-cut plot, the shoot biomass, total nitrogen (Tot-N) and total phosphorus (Tot-P) content peaked in September. The mean rate of dry matter production (RPD), defined as the mean daily rate of dry matter production per unit area per day between harvests, attained maximum rates of 12.8g m-2d-1 and 4.2g m-2d-1 for the control and June-cut plots, respectively, indicating that annual harvesting of emergent vegetation may not have any beneficial effect on biomass production or nutrient content under Irish climatic conditions. peer-reviewed

Highway surface runoff contains pollutants such as total suspended solids (TSS), hydrocarbons, de-icing salts, and heavy metals. Treatment methods for highway runoff include storage/treatment facilities, such as constructed wetlands (CWs), detention ponds, or sedimentation tanks; stormwater infiltration facilities, such as soakaways, trenches, or basins; and filter strips and swales. These facilities are commonly referred to as SuDS - Sustainable Drainage Systems.The treatment of highway runoff using CWs is widely used in America, Australia and most of Europe. CWs are a suitable choice for the treatment of highway runoff, due to their relative low cost and good efficiency in treating contaminants such as TSS, organic matter, heavy metals, as well as hydrocarbons and inorganic salts. This review paper aims to characterise highway surface runoff, quantify the removal mechanisms of influent pollutants, evaluate the performance of CWs in the treatment of highway runoff, discuss their design criteria, and compare their performance with other treatment methods. peer-reviewed

In Ireland, agricultural activities have been identified as major sources of nutrient input to receiving waters and it has been estimated that these activities contribute 75.3% of the nitrogen (N) and 33.4% of the phosphorus (P) in these waters. Strategy at European level focuses on the prevention of nutrient loss by improved farm management. However, it does not focus on nutrient remediation or incidental nutrient loss of farmyard manures to surface and groundwater. This review describes the impact of agriculture on the environment in Ireland and examines emerging technologies for agricultural wastewater treatment. An integrated approach at pre-treatment and field stages for nitrate (NO3) remediation and P control is recommended. peer-reviewed

peer-reviewed Nutrient loss from agricultural sources to water continues to be a national challenge. Diffuse pollution from agricultural sources is considered to be the primary cause of slight-to-moderate water pollution in Ireland, but agricultural point sources, such as farmyards, are often not considered due to their scattered spatial distribution and small areal extent. Agricultural point sources tend to be small and localised hot spots of nutrients and, therefore, can be efficiently treated using environmental technologies developed for wastewater and contaminated land treatment. A small area associated with soiled water irrigation, on a 4.27 ha case study site at Teagasc, Johnstown Environmental Research Centre, Ireland, was identified, where groundwater nitrate-nitrogen (NO3-N) concentration exceeds the maximum admissible drinking water concentration of 11.3 mg N L-1. A continuous, shallow permeable reactive barrier may be suitable to remediate point source pollution at this site. A methodology, based on site and groundwater characterisation, successfully located a site for a permeable reactive barrier.

Journal article Intermittent sand filtration is a common and effective method for treating septic tank effluent. However, if the loading rate is too high, clogging and ponding of the sand filter surface layer can occur due to the accumulation of excessive biomass and the deposition of suspended solids. This ponding limits the practicality of sand filtration as it makes it necessary to take the filter out of service for maintenance. The objective of this study was to develop and test, on-site, a new hybrid filter system that would reduce the risk of clogging at an organic loading rate substantially greater than the maximum recommended loading rate for intermittent sand filters. The system comprised a 0.6 m deep horizontal flow biofilm reactor (HFBR) over a 0.85 m deep stratified sand filter. The HFBR consisted of a stack of 20 horizontal corrugated polyvinyl chloride sheets, at 32 mm vertical spacings. The sheets were arranged so that the wastewater flowed over and back along alternate sheets down through the stack. The main biofilm growth formed on these sheets. The hybrid filter was loaded with septic tank effluent from an office/garage complex at the rate of 206 L/m(2) day for a period of 400 days in two phases. During the first phase, the effluent volume of 600 L/day was applied in 24 doses/day for 10 min/dose, and during the second phase in 6 doses/day for 40 min/dose. Biofilms in the HFBR substantially reduced the organic and suspended solids loads that reached the sand filter surface and allowed an average total biochemical oxygen demand (BODT) loading rate, based on HFBR plan area, of 37 g BODT/m(2) day to be applied to the system without clogging. This rate was substantially greater than the maximum recommended loading rate of 24 g BODT/m(2) day for intermittent sand filters. During both loading phases a BODT removal of 94% was achieved and nitrification was nearly complete. The average effluent BODT was 12 +/- 4 mg/L during both phases. The hybrid filter system appeared to perform better in terms of suspended solids handling and nitrification during the more frequent dosing phase. The hybrid filtration system offers a more compact alternative to intermittent sand filtration on its own with little risk of clogging. peer-reviewed

Journal article This laboratory study examined the use of various wood materials as a carbon source in horizontal flow filters to denitrify nitrate-nitrogen (NO3-N) from a synthetic wastewater. The filter materials were: sawdust ( Pinus radiata), sawdust and soil, sawdust and sand, and medium-chip woodchippings and sand. Two influent concentrations of NO3-N, 200 mgL(-1) and 60 mgL(-1), loaded at 2.9 to 19.4 mg NO3-N kg(-1) mixture, were used. The horizontal flow filter with a woodchippings/sand mixture and an influent NO3-N concentration of 60 mgL(-1), which operated over a study duration of 166 days, performed best, yielding a 97% reduction in NO3-N at steady-state conditions. Teagasc (Walsh fellowship) peer-reviewed

A stratified sand filter column, operated in recirculation mode and treating synthetic effluent resembling high-strength dairy wastewaters was studied over a 342-d duration. The aim of this paper was to examine the organic, total suspended solids (TSS) and nutrient removal rates of the sand filter, operated in recirculation mode, under incrementally increasing hydraulic and organic loading rates and to propose a field filter-sizing criterion. Best performance was obtained at a system hydraulic loading rate of 10 L m(-2) d(-1); a higher system hydraulic loading rate (of 13.4 L m(-2) d(-1)) caused surface ponding. The system hydraulic loading rate of 10 L m(-2) d(-1) gave a filter chemical oxygen demand (COD), TSS, and total kjeldahl nitrogen (TKN) loading rate of 14, 3.7, and 2.1 g m(-2) d(-1), respectively, and produced consistent COD and TSS removals of greater than 99%, and an effluent NO(3)-N concentration of 42 mg L(-1) (accounting for an 86% reduction in total nitrogen (Tot-N)). As the proportional surface area requirement for the sand filter described in this study is less than the recommended surface area requirement of a free-water surface (FWS) wetland treating an effluent of similar quality, it could provide an economic and sustainable alternative to conventional wetland treatment.

Journal article A laboratory sequencing batch biofilm reactor (SBBR), operated for a period of 158 days, was used to treat domestic-strength synthetic effluent. The biofilm. reactor comprised a bulk fluid reactor, a biofilm plastic module, a synthetic wastewater feed tank, and pneumatic devices with pneumatic controls. The reactor cycle time was 8 h, and its operation consisted of five phases: feeding (59 min), mixing (1 min), anoxic/anaerobic (3 h), aerobic (3 h), and settling (1 h). At total chemical oxygen demand (CODT) loading rates of 8.8 g CODT m(-2) d(-1) and 1.2 kg CODT m(-3) d(-1), expressed in terms of the plastic module surface area and reactor volume, respectively, the SBBR had average removal rates of 8.3 g CODT m(-2) d(-1) and 1.1 kg CODT m(-3) d(-1), or 94%. Total orthophosphorus (M-PT) and filtered orthophosphorus (PO4-P-F) removals were 44% and 50%, respectively. peer-reviewed