Nitrogen removal in maturation WSP ponds via biological uptake and sedimentation of dead biomass

In this work a set of experiments was undertaken in a pilot-scale WSP system to determine the importance of organic nitrogen sedimentation on ammonium and total nitrogen removals in maturation ponds and its seasonal variation under British weather conditions. Two maturation ponds in series (M1 and M2) were monitored seasonally from September 2004 to May 2007. The nitrogen content in collected sediment samples varied from 4.17 to 6.78 percent (dry weight) and calculated nitrogen sedimentation rates ranged from 291 to 2,868 g N/ha d in M1 and from 273 to 2,077 g N/ha d in M2. The increment of chlorophyll-a in M1 and M2 maturation pond effluents had a very good correlation with the corresponding increment of VSS (algal biomass) and suspended organic nitrogen; therefore, the occurrence of biological (algal) nitrogen uptake was confirmed. After sedimentation of the dead algal biomass, it was clear that algal-cell nitrogen was recycled from the sludge layer into the pond water column. An important portion (51% in M1 and 39% in M2) of the nitrogen taken up by the in-pond algae was finally accumulated as sludge after anaerobic digestion. Biological (mainly algal) uptake of inorganic nitrogen species and further sedimentation of dead biomass is one of the major mechanisms controlling ammonium and nitrogen removal in maturation WSP, particularly when environmental and operational conditions are favourable for algal growth

The influence of algal biomass on tracer experiments in maturation ponds

Tracer experiments are of concern to wastewater treatment engineers and researchers because of the importance of determining hydraulic regimes and retention times in wastewater treatment units. In this work, a pilot-scale maturation waste stabilisation pond (WSP) was spiked with Rhodamine WT, in order to determine how suspended organic matter would interfere with its performance as a tracer in a domestic wastewater treatment unit which had a high content of suspended algal biomass. A primary maturation pond was spiked in three separate runs with different levels of algae (high, medium and low), with a known amount of Rhodamine WT (20% v/v); the tracer was measured in the pond effluent in real time every 20 min for 3θ (the theoretical retention time, θ = 17 d). Algal biomass was monitored weekly from influent, column and effluent water samples by chlorophyll-a determination. The results show that algal biomass has a strong influence on the behaviour of Rhodamine WT as a tracer and therefore the hydraulic characteristicsm calculated from tracer curves may be affected by tracer adsorption on suspended organic matter

Enhanced phosphorus removal in a waste stabilization pond system with blast furnace slag filters

In this work a tertiary horizontal-flow blast furnace slag (BFS) filter was tested for phosphorus removal under laboratory and field conditions. Laboratory experiments were conducted in a benchscale BFS filter for phosphorus adsorption capacity at equilibrium conditions using P-spiked water. On-site, the performance of a pilot-scale BFS filter was monitored for phosphorus removal from the final effluent of a pilot-scale WSP system located in Esholt (Bradford, UK), which comprises a primary facultative pond and a secondary aerated rock filter (ARF) in series. Adsorption capacity (q) results showed that BFS has high affinity for inorganic P species and it can remove up to 30 g P/kg BFS; however, q values are strongly dependent on the initial P concentration. The pilot-scale BFS filter tested on-site performed better for longer (<2 mg P/L) than the laboratory-scale filter, even though despite the latter received the same hydraulic and P loadings (1.8 m3/m3 d and 18 g P/m3 d, respectively). Both the laboratory and field results showed that BFS filters are an appropriate low-cost technology to upgrading small wastewater treatment systems for phosphorus removal

Uncertainty and Sensitivity Analysis in Reservoir Modeling: a Monte Carlo Simulation Approach

Water resource modelling plays a crucial role in water resources management, but it involves many inherent uncertainties. This research investigates how epistemic uncertainties affect reservoir water budgets, projecting forward over a 30 year period using Monte Carlo simulation. It encompasses long-term variations in water demand, reservoir volume, precipitation, evaporation and inflow, while also considering siltation processes, reservoir dredging, population growth, reduced water consumption, and the hydrological impacts of climate change. The research focuses on fifty reservoirs in a semi-arid region of Brazil. The findings demonstrate that some reservoirs consistently met their demands with high level reliability, even within a wide range of uncertainty. Conversely, reservoirs with morphohydric indices indicating a tendency toward water scarcity are significantly affected by input variability introduced through uncertainty analysis. An empirical model is proposed to estimate the probability of these reservoirs achieving the reference volume reliability of 90%, while considering the uncertainties of: annual average inflow, reservoir maximum volume and annual demand. Sensitivity analysis reveals that reservoir inflow and demand are the two most influential variables affecting a reservoirs’ ability to meet its demand. For over exploited reservoirs, variations in these variables strongly impact the volume reliability. This research provides a valuable tool for estimating the likelihood of reaching a 90% volume reliability, while taking into account the inherent uncertainties in the modeling process. Additionally, it identifies key variables that have the most influence on the reservoirs’ ability to meet its demand. Notably, this study conducts uncertainty and sensitivity analyses in the context of physical and hydrological reservoir features for a large number of reservoirs, adding novelty to the research field

Effect of macronutrients (carbon, nitrogen, and phosphorus) on the growth of Chlamydomonas reinhardtii and nutrient recovery under different trophic conditions

More stringent discharge standards have led to the development of an alternative nutrient recovery system from wastewater. Microalgae cultivation in wastewater treatment works has presented considerable promise from the perspective of sustainable resource management. Growth kinetics models are useful tools to optimize nutrient recovery from wastewater by algal uptake. Therefore, this research aims to identify the growth kinetics of Chlamydomonas reinhardtii under both heterotrophic and phototrophic conditions with different nutrient concentrations that typify those found in wastewater treatment works. In addition, the effects of macronutrients (C, N, and P) on heterotrophic and phototrophic microalgae growth and nutrient recovery were studied. Greater specific growth rates were achieved under heterotrophic conditions than in phototrophic cultivation. The maximum specific growth rates and nutrient recovery efficiencies were achieved at 5 mg P L−1 under both heterotrophic and phototrophic growth conditions. Nitrate was the preferred form of nitrogen source under heterotrophic conditions, while nitrogen sources did not present any significant influences in the phototrophic cultivation. Specific growth rates reported for both heterotrophic and phototrophic microalgae at lower carbon concentrations (3.10 d−1 and 0.46 d−1, sequentially) were higher than those at higher carbon concentrations (1.95 d−1 and 0.22 d−1, respectively). C. reinhardtii presented an extreme capacity to adapt and grow at all experimental conditions tested in heterotrophic and phototrophic cultivations

Influence of pH on hydrothermal treatment of swine manure: Impact on extraction of nitrogen and phosphorus in process water

This study investigates the influence of pH on extraction of nitrogen and phosphorus from swine manure following hydrothermal treatment. Conditions include thermal hydrolysis (TH) at 120°C and 170°C, and hydrothermal carbonisation (HTC) at 200°C and 250°C in either water alone or in the presence of 0.1M NaOH, H2SO4, CH3COOH or HCOOH. Phosphorus extraction is pH and temperature dependent and is enhanced under acidic conditions. The highest level of phosphorus is extracted using H2SO4 reaching 94% at 170°C. The phosphorus is largely retained in the residue for all other conditions. The extraction of nitrogen is not as significantly influenced by pH, although the maximum N extraction is achieved using H2SO4. A significant level of organic-N is extracted into the process waters following hydrothermal treatment. The results indicate that operating hydrothermal treatment in the presence of acidic additives has benefits in terms of improving the extraction of phosphorus and nitrogen

Bioaerosol deposition in single and two-bed hospital rooms: a numerical and experimental study

This study considers the ability of computational fluid dynamics (CFD) simulations to accurately predict bioaerosol deposition in indoor environments; it then further explores the influence that different room layouts have on these deposition patterns. Experiments are conducted to quantify the spatial deposition of aerosolised Staphylococcus aureus in an aerobiology test room (4.26m (L) x 3.36m (W) x 2.26m (H)). Three different room layouts were considered in this study: the empty room, a single patient and two-bed hospital accommodation replicas. CFD simulations of these scenarios show that a realistic prediction of spatial deposition is feasible and that a Reynolds Stress (RSM) turbulence model yields significantly better results than the k-ε RNG turbulence model used as a default feature in most indoor air simulations. Experimental and simulation results both demonstrate that small particle bioaerosols are dispersed throughout a room with only slightly higher deposition close to the source. However, a physical partition separating patients is shown to be effective at reducing cross-contamination of neighbouring patient zone