Long-term phosphorus removal by Ca and Fe-rich drainage filter materials under variable flow and inlet concentrations.

Phosphorus (P) losses from tile-drained agricultural fields may degrade surface water quality by accelerating eutrophication. Among the different edge-of-field technologies, compact filter systems using different filter materials have been identified as potentially effective solutions for removing P from drainage water before discharge downstream. This study investigated the long-term (>696 days) P removal efficiency of 5 different filter materials in a column setup, using artificial drainage water (pH 6).

Improvement in CH/CO ratio and CH yield as related to biomass mix composition during anaerobic co-digestion.

Sixteen data sets (two of which were measured in this study) with a combined total of 145 measurements of ultimate methane yield (UMY) during mono- and co-digestion of ternary biomass mixtures were used to assess impact of co-digestion on the relative change in UMY (ΔUMY) as a function of biomass mix composition. The data involved 9 biomass materials (brewery spent grains, chicken manure, cow manure, fresh grass clippings, pig manure, primary sewage sludge, vegetable food waste, wheat straw, and rice straw). Results of the assessment shows that co-digestion in 85% of yields positive values of ΔUMY regardless of the biomass materials used, however, a smaller fraction (15%) resulted in negative ΔUMY during co-digestion.

Combinations of fungal and milling pretreatments for enhancing rice straw biogas production during solid-state anaerobic digestion.

Rice straw was pretreated by different combinations of physical (milling) and biological (incubation with Pleurotus ostreatus fungus) treatment to improve its biodegradability and biogas production during solid-state anaerobic digestion (SS-AD). Effects of milling (⩽2mm) and incubation time (10, 20 and 30d), on lignin, cellulose, and hemicellulose degradation during fungal pretreatment and methane yield during digestion were assessed by comparison with untreated rice straw. Both incubation time and milling had significant impacts on both lignin removal during fungal pre-treatment and methane yield during digestion.

Uncertainty in degradation rates for organic micro-pollutants during full-scale sewage sludge composting.

Composting can potentially remove organic pollutants in sewage sludge. When estimating pollutant removal efficiency, knowledge of estimate uncertainty is important for understanding estimate reliability. In this study the uncertainty (coefficient of variation, CV) in pollutant degradation rate (K1) and relative concentration at 35days of composting (C35/C0) was evaluated.

Impact of compost process conditions on organic micro pollutant degradation during full scale composting.

Knowledge about the effects of oxygen concentration, nutrient availability and moisture content on removal of organic micro-pollutants during aerobic composting is at present very limited. Impact of oxygen concentration, readily available nitrogen content (NH4(+), NO3(-)), and moisture content on biological transformation of 15 key organic micro-pollutants during composting, was therefore investigated using bench-scale degradation experiments based on non-sterile compost samples, collected at full-scale composting facilities. In addition, the adequacy of bench-scale composting experiments for representing full-scale composting conditions, was investigated using micro-pollutant concentration measurements from both bench- and full-scale composting experiments.

Biogas and methane yield in response to co- and separate digestion of biomass wastes.

The impact of co-digestion as opposed to separate digestion, on biogas and methane yield (apparent synergetic effects) was investigated for three biomass materials (pig manure, cow manure and food waste) under mesophilic conditions over a 36 day period. In addition to the three biomass materials (digested separately), 13 biomass mixtures (co-digested) were used. Two approaches for modelling biogas and methane yield during co-digestion, based on volatile solids concentration and ultimate gas and methane potentials, were evaluated.

Modeling organic micro pollutant degradation kinetics during sewage sludge composting.

Degradation of 13 different organic micro-pollutants in sewage sludge during aerobic composting at 5 different temperatures over a 52 day period was investigated. Adequacy of two kinetic models: a single first order, and a dual first order expression (using an early (first 7 days) and a late-time (last 45 days) degradation coefficient), for describing micro-pollutant degradation, and kinetic constant dependency on composting temperature were evaluated. The results showed that both models provide relatively good descriptions of the degradation process, with the dual first order model being most accurate.

Impact of compost process temperature on organic micro-pollutant degradation.

Aerobic composting has gained considerable attention because of its ability to remove organic micro-pollutants. Compost process temperature is a key parameter controlling degradation rate. Impact of process temperature on removal of 15 key organic micro-pollutants often found in sewage sludge (including two metabolites) during sewage sludge composting was investigated at 18-70°C over 52 days.

Quantifying measurement uncertainty in full-scale compost piles using organic micro-pollutant concentrations.

Reductions in measurement uncertainty for organic micro-pollutant concentrations in full scale compost piles using comprehensive sampling and allowing equilibration time before sampling were quantified. Results showed that both application of a comprehensive sampling procedure (involving sample crushing) and allowing one week of equilibration time before sampling reduces measurement uncertainty by about 50%. Results further showed that for measurements carried out on samples collected using a comprehensive procedure, measurement uncertainty was associated exclusively with the analytic methods applied.

Optimized sampling strategy for measurement of biomass properties during full-scale composting.

Biomass to be composted is often very heterogeneous and collection of representative samples for determination of compost properties is therefore difficult, especially under full-scale conditions. During full-scale composting different biomasses in the amount of 10-100 tons are mixed, yielding a very heterogeneous mixture. Final sample size for compost property determination is usually a few grams compared with compost pile masses of hundreds of tons.

Cities as development drivers: from waste problems to energy recovery and climate change mitigation.

There is a strong connection between economic growth and development of cities. Economic growth tends to stimulate city growth, and city economies have often shaped innovative environments that in turn support economic growth. Simultaneously, social and environmental problems related to city growth can be serious threats to the realization of the socio-economic contributions that cities can make.

Energy and greenhouse gas balances for a solid waste incineration plant: a case study.

Energy and greenhouse gas balances for a waste incineration plant (Reno-Nord I/S, Aalborg, Denmark) as a function of time over a 45-year period beginning 1960 are presented. The quantity of energy recovered from the waste increased over time due to increasing waste production, increasing lower heating value of the waste and implementation of improved energy recovery technology at the incineration plant. Greenhouse gas (GHG) balances indicated progressively increasing GHG savings during the time period investigated as a result of the increasing energy production.

Optimizing feed composition for improved methane yield during anaerobic digestion of cow manure based waste mixtures.

This study investigated methane yield via anaerobic digestion of multi-component substrates based on mixtures of biodegradable single-component substrates with cow dung as main component. Bench and full-scale digestion experiments were carried out for both single and multi-component substrates to identify the relationship between methane yield and substrate composition. Results from both bench- and full-scale experiments corresponded well and showed that using multi-component substrates increases the methane yield much more than what would be expected from digestion of single substrates.

Gas dispersion and immobile gas volume in solid and porous particle biofilter materials at low air flow velocities.

Gas-phase dispersion in granular biofilter materials with a wide range of particle sizes was investigated using atmospheric air and nitrogen as tracer gases. Two types of materials were used: (1) light extended clay aggregates (LECA), consisting of highly porous particles, and (2) gravel, consisting of solid particles. LECA is a commercial material that is used for insulation, as a soil conditioner, and as a carrier material in biofilters for air cleaning.

Organic micropollutant degradation in sewage sludge during composting under thermophilic conditions.

Degradation of 12 common organic micropollutants in sewage sludge representing bactericides, flame retardants, fragrances, vulcanizers, and plasticizers (part of many common products) during thermophilic composting was investigated. Micropollutant concentrations, compost temperature, water content, and organic matter content were measured over 24 days in a full-scale compost windrow made from digested sewage sludge, yard waste, and horse manure. Composting took place indoors, and the windrow was turned several times during the experimental period.

Variability of soil potential for biodegradation of petroleum hydrocarbons in a heterogeneous subsurface.

Quantifying the spatial variability of factors affecting natural attenuation of hydrocarbons in the unsaturated zone is important to (i) performing a reliable risk assessment and (ii) evaluating the possibility for bioremediation of petroleum-polluted sites. Most studies to date have focused on the shallow unsaturated zone. Based on a data set comprising analysis of about 100 soil samples taken in a 16 m-deep unsaturated zone polluted with volatile petroleum compounds, we statistically and geostatistically analysed values of essential soil properties.

Phosphorus and zinc dissolution from thermally gasified piggery waste ash using sulphuric acid.

Ash from thermally gasified piggery waste (GA) was treated with sulphuric acid (H(2)SO(4)) using two extraction methods. First different loads (0.39-0.

Assessing the impacts of changes in treatment technology on energy and greenhouse gas balances for organic waste and wastewater treatment using historical data.

Historical data on organic waste and wastewater treatment during the period of 1970-2020 were used to assess the impact of treatment on energy and greenhouse gas (GHG) balances. The assessment included the waste fractions: Sewage sludge, food waste, yard waste and other organic waste (paper, plastic, etc.).