RESUMEN
Because of the naturally limited anaerobic degradability and limited biogas yield of raw sludge (RS), this study aims to increase the biogas production of primary sludge (PS) and waste activated sludge (WAS) by the integration of thermal alkaline process (TAP). PH 11 is confirmed to be the most suitable pH value for the TAP of both sludges. Moreover, with the pretreatment at pH 11 and 160 °C (6 bar) for 30 min, the investigated PSs and WASs achieved an increased biogas production of up to 81 % and 72 %, respectively. The improved net electricity production of WASs after TAP varied between 15-43 % compared to conventional WAS digestion. However, the TAP of PS at pH 11 enhanced the biogas production by 1-81 %, which did not constantly contribute to an improved net electricity production.
Asunto(s)
Biocombustibles , Aguas del Alcantarillado , Concentración de Iones de Hidrógeno , Álcalis/química , Temperatura , Electricidad , Anaerobiosis , Calor , Metano/metabolismoRESUMEN
For a novel approach of resource-efficient water reuse, a municipal wastewater treatment plant was extended at pilot scale for advanced wastewater treatment, i.e., ozonation and biological activated carbon filtration, and a hydroponic system for reclaimed water driven lettuce cultivation. The treatment specific wastewater lines with the corresponding lettuce plants, differentiated into roots and shoots, were monitored for priority wastewater micropollutants, i.e., acesulfame (sweetener), caffeine (stimulant), carbamazepine, diclofenac, ibuprofen, sulfamethoxazole with acetyl-sulfamethoxazole (human pharmaceuticals), 1H-benzotriazole, and 4/5-methylbenzotriazole (industrial chemicals). As clearly demonstrated, conventional tertiary treatment could not efficiently clean up wastewater. Removal efficiencies ranged from 3% for carbamazepine to 100% for ibuprofen. The resulting pollution of the hydroponic water lines led to the accumulation of acesulfame, carbamazepine, and diclofenac in lettuce root systems at 32.0, 69.5, and 135 µg kg-1 and in the uptake of acesulfame and carbamazepine into lettuce shoots at 23.4 and 120 µg kg-1 dry weight, respectively. In contrast, both advanced treatment technologies when operating under optimized conditions achieved removal efficiencies of > 90% also for persistent micropollutants. Minimizing the pollution of reclaimed water thus met one relevant need for hydroponic lettuce cultivation.
Asunto(s)
Contaminantes Químicos del Agua , Purificación del Agua , Humanos , Hidroponía , Lactuca , Eliminación de Residuos Líquidos , Aguas Residuales , Agua , Contaminantes Químicos del Agua/análisisRESUMEN
Sludge production in microbial bioelectrochemical systems (BES) was assessed in conjunction with anaerobic and aerobic control reactors. Effluent after primary settling tank (EAPS) and depleted EAPS spiked with acetate were treated. The reactors were loaded with total suspended solids (TSS) and chemical oxygen demand (COD) at average loading rates of 22 mg TSS d(-1)L(-1) and 86 mg COD d(-1)L(-1), respectively. Carbon cloth anode equipped BES reactors delivered the highest performance. They achieved on average a COD removal of 80%, a Coulomb efficiency of 77% for EAPS, a maximum current density of 39 µA cm(-)(3)/175 µA cm(-)(2) for EAPS and a TSS removal of 59%, yielding a sludge production of only 80 mg TSS per g ΔCOD. This study provides further evidence that BES can improve the economics of wastewater treatment via lower sludge production as well as providing a framework for understanding sludge production in BES.
Asunto(s)
Aguas del Alcantarillado , Aguas Residuales , Purificación del Agua , Análisis de la Demanda Biológica de Oxígeno , Reactores Biológicos , Aguas del Alcantarillado/análisis , Aguas del Alcantarillado/química , Aguas Residuales/análisis , Aguas Residuales/químicaRESUMEN
This study focuses on the challenges of the scaling up process of bioelectrochemical systems on the example of a technical scale microbial electrolysis cell referred to as the "prototype". Anodically treating real wastewater and operated in continuous mode at a hydraulic retention time of 1.23 d with an average chemical oxygen demand (COD)-loading rate of 0.5 g O2 d(-1) L Reactor(-1) the prototype on average showed COD removal efficiency of 67% with effluent concentrations of 210 mg O2 L(-1) and an ammonium elimination rate of 17.8 ± 3.9 mg Nd(-1) L Reactor(-1) resulting in effluent concentrations of 30.7 ± 3.7 mg NL(-1) with a removal efficiency of 40% at a current generation of 72 µA cm(-2) and Coulomb efficiency of 11%. A model is described as a method for comparing conventional and BES based technology using the above mentioned criteria and balancing them against the respective loading rates.
Asunto(s)
Electrólisis/instrumentación , Análisis de la Demanda Biológica de Oxígeno , Aguas Residuales , Purificación del Agua/instrumentaciónRESUMEN
Sewage sludge accumulating during biological wastewater treatment has to be treated appropriately to avoid impacts on the environment and risks to public health. Especially pathogen reduction is necessary when sludge is disposed or reused in such a way that human contact is possible. In industrialized countries various sludge treatment technologies are available, but these are often only approved under local conditions. When exporting these technologies and experiences to other countries, a number of factors have to be taken into account including climatic, sociocultural, political and financial aspects. This paper gives an overview of current knowledge regarding sewage sludge treatment in developing countries. Various sanitation projects are realized worldwide and experiences from these plants already in operation are summarized. Results of on going laboratory experiments in climatic chambers regarding aerobic and anaerobic stabilization as well as lime treatment are shown to define the best-practicable sludge treatment technology for a certain climate. Options for final reuse or disposal are presented depending on end-product quality.