Wastewater

About: Wastewater is a research topic. Over the lifetime, 92512 publications have been published within this topic receiving 1256590 citations. The topic is also known as: waste water.

Degradation of pharmaceuticals in wastewater using immobilized TiO2 photocatalysis under simulated solar irradiation

Abstract: Pharmaceutically active compounds (PhACs) are not efficiently removed in wastewater treatment plants and are released into surface waters resulting in toxin accumulation. The aims of this study were to investigate the effect of solar irradiation on PhACs in wastewater using immobilized TiO 2 present as a catalyst, and to study the potential of this photocatalysis technique as a post-treatment process for wastewater effluent. We treated a mixture of PhACs spiked in wastewater effluent and in deionized water as a control with simulated solar irradiation for 96 h. Experiments were conducted with immobilized TiO 2 (photocatalysis) and without (photolysis). First, TiO 2 was successfully immobilized on 200–500 μm sand by using a sol–gel method. The photocatalysis resulted in high removal efficiencies for poorly biodegradable PhACs in wastewater effluent: 100% for propranolol, 100% for diclofenac, and 76 ± 3% for carbamazepine. Photodegradation of all four PhACs followed pseudo-first-order kinetics, and the kinetic constant of photocatalysis was much higher than that of photolysis in the absence of a catalyst. Dissolved organic matter (DOM) in wastewater effluent enhanced photodegradation of PhACs by producing reactive radicals. However, at the same time, DOM inhibited photodegradation, possibly because DOM reforms the oxidation intermediates of PhACs into parent compounds. From an application perspective, water depth was confirmed as a key factor in photodegradation of PhACs due to light attenuation by modelling and experimental results. In addition, after photocatalysis, toxicity of PhACs decreased and biodegradability of wastewater effluent increased slightly. In conclusion, the technique is a promising post-treatment process to improve water quality, prior to discharging to natural waters or to polishing water treatment systems such as wetlands and lagoons.

Remediation of heavy metals in drinking water and wastewater treatment systems: processes and applications.

Abstract: In small quantities, certain heavy metals are nutritionally essential for a healthy life. The heavy metals linked most often to human poisoning are lead, mercury, arsenic and cadmium. Other heavy metals, including copper, zinc and chromium are actually required by the body in small amounts, but can also be toxic in larger doses. They have the ability of dissolving in wastewaters and when discharged into surface waters, they can be concentrated and travel up the food chain. They can also seep into groundwater, hence contaminating drinking water, thereby harming the consumers of that water. The enactment of several water legislations and guidelines worldwide coupled with the need for environmental sustainability has necessitated the need for several stringent regulations for drinking water supply and wastewater discharge. To achieve unpolluted drinking water distribution and wastewater discharge, several technologies and processes for heavy metal remediation are currently in use. This review was therefore aimed at elucidating the major available technologies for heavy metal remediation in water, with emphasis on their processes and applications. Currently, no one of the existing technologies for heavy metal remediation (chemical remediation, phytoremediation or microbial remediation) is without some form of merits and demerits. There is therefore a proposed need for the utilization of safe and economical multiple/integrated approach for heavy metal remediation. The application of this may offer enormous public health, environmental and cost benefits. Key words: Heavy metals, remediation, water.