Energy Integration in Wastewater Treatment Plants by Anaerobic Digestion of Urban Waste: A Process Design and Simulation Study

The process simulation performed in the present study aimed at investigating energetically self-sufficient wastewater treatment plant of 500,000 population equivalents. To implement this, three different scenarios were evaluated using computational tools named GPS-X® and SuperPro®. They were designed based on municipal wastes recovery to energy generation and its utilisation within the facility. An anaerobic/anoxic/oxic process for biological treatment of wastewater was considered and mesophilic anaerobic digestion at different scenarios (1) primary sludge (PS) with waste activated sludge (WAS), (2) PS with thermally hydrolysed WAS, and (3) PS with WAS and organic fractions derived from municipal solid waste. The results from scenario 1 and scenario 2 showed only enough thermal energy to meet their demand (they reach only 44 and 52% of electrical self-sufficiency, respectively), while positive net thermal and electrical energy result in scenario 3 from codigestion of sewage sludge and the organic fraction of municipal solid waste. The main limitation of tools used is their lack of sensitivity to economies of scale and their dependence on real data used for process design to obtain more accurate results

Anaerobic co-digestion of sewage sludge and grease trap: Assessment of enzyme addition

International audienceAnaerobic co-digestion of grease trap and sewage sludge from a wastewater treatment plant is evaluated.Enzyme-lipase application, both addition and dosage, are evaluated by fitting the methane productionof biochemical potential tests with the first order model. The enzyme addition effect, at 2, 5 and 10% ofgrease trap (%GT VSFED−1) and the enzymes doses, between 0.25 and 1.67% (v/v), without and with greasetrap presence were studied. Grease trap addition showed a negative effect on the waste biodegradability,which was completely overcome by the addition of lipase. Enzyme addition improved notably themethane production for all grease trap fractions studied. In regards to the dosage, the best result wasachieved between 0.33 and 0.83% (v/v) of enzyme. The co-digestion of sewage sludge and grease trapmay be a feasible process by using lipases due to the saving in operational costs and the increase in thebiogas productio

Landslide and Environmental Risk from Oil Spill due to the Rupture of SOTE and OCP Pipelines, San Rafael Falls, Amazon Basin, Ecuador

A landslide generated an environmental risk due to a provoked oil spill on April 7, 2020, with the SOTE and OCP pipelines rupture. This research aims to determine the areas susceptible to landslides in the river basin Quijos of the Coca River and estimate the environmental risk from exposure to the oil spill. A water analysis of the Coca River was performed by using the Mora-Vahrson method and GIS tools. The subsequent water sampling was probabilistic in a simple random way, and the analyzed parameters were oils and grease, Ba, Cd, Cr, BOD, COD, TPH, OD, Pb, and SST. The results show that 61.17% (572.68 km2) of the total studied area (936.19 km2) is susceptible to landslide hazards. In detail, 0.25% (2.34 km2) of the area is considered to be of very high susceptibility, 26.72% (250.12 km2) of high susceptibility, 11.82% (110.66 km2) of moderate susceptibility, and 0.04 (0.37 km2) of low susceptibility. Four of them were within the permissible limits from the ten analyzed parameters, which correspond to Ba with 0.70 mg/L, OD with 7.4% of saturation, BOD5 with 2 mg/L, and COD with 25 mg/L. The other six parameters, including oils and fats, exhibited a significant increase in concentrations after the oil spill, yielding Cd 0.05 mg/L, total Cr 0.45 mg/L, TPH 0.20 mg/L, Pb 0.20 mg/L, and SST 20%. These results are outside the permissible limits, meaning that the river waters are contaminated