Two openings on the side of the anaerobic compartments were considered for recirculation. The independent variables were the type of cathodic zone (aerobic and anaerobic), the VSS concentration of the treated sludge (8 and 16 g/L), and the pH in the anodic zone (5 and 6).
Organic matter removal and Coloumbic efficiency
Statistical analysis performed for Coulombic Efficiency (CE) using a model with R2 of 0.975 and adj-R2 of 0.941 showed that the two factors that strongly affected CE were cathodic zone type and initial pH. 25], who stated that fermentation and methanogenesis are not electrode-dependent reactions, so they can occur with any external resistance, as long as the redox potential in the solution is low enough and bacteria are present to obtain more energy from these processes. as from the oxidation of the substrate driven by the electrodes.
Electrochemical performance of the bMFCs
The use of aerobic cathodic zone and initial pH of 6 allows the achievement of better coulombic efficiencies. In green, the operating conditions that included the Aerobic Cathodic Chamber (Ae.C.Ch.) and in purple those that included the Anaerobic Cathodic Chamber (An.C.Ch.).
Conclusions
A state of the art review of microbial fuel cells: A promising technology for wastewater treatment and bioenergy. Treatment of carbon fiber brush anodes to improve energy production in air-cathode microbial fuel cells.
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Introduction
Consequently, their presence in the sewage is very problematic for the treatment performance of the plant. Furthermore, the presence of pharmaceuticals in the effluent of sewage/wastewater treatment plants is very toxic in many ways to the soil and surrounding water bodies [1-5, 21].
Occurrence of pharmaceuticals in sewage/wastewater
Wastewater treatment plants are therefore considered one of the important anthropogenic sources of release of drugs into the environment, together with industrial discharges, hospital wastewater, etc.
Removal of pharmaceuticals from sewage/wastewater
In addition, the upgrading of the conventional treatment plants can further minimize the environmental release of the various medicines. Although the AOPs are considered as one of the most effective treatment options for the removal of a variety of drugs, their full-scale applications are still limited due to the number of challenges. In the secondary stage, the drugs undergo several processes such as biodegradation, sorption, dispersion, dilution, photodegradation and evaporation.
The importance of tertiary treatment in WWTPs is comprehensive as it complements secondary treatment and those pollutants that are not removed in the second stage are removed in the tertiary stage. The main reactive species in AOP for the degradation/mineralization of pharmaceuticals are hydroxyl radicals (OH•) and the number of parallel reactions is reported in their mechanism. The appropriateness of the adoption of different AOPs is mainly based on the wastewater characteristics, the objectionable nature of the target compounds, available resources and economic conditions [50].
Some of the disadvantages of the Fenton process are low operating pH requirement and high sludge production, the chances of the pharmaceuticals accumulating in the iron sludge produced after the treatment [41]. The combined approach of the ozonation-biological process is found to be most effective for the removal of pharmaceuticals from secondary urban wastewater.
Conclusion
Presence and removal of organic micropollutants: An overview of the watch list of EU Decision 2015/495. Environmental Impact Assessment of Advanced Urban Wastewater Treatment Technologies for the Removal of Priority Substances and Contaminants from. An overview of the occurrence of micropollutants in the aquatic environment and their fate and removal during wastewater treatment.
Fate and distribution of pharmaceuticals in wastewater and sewage sludge from conventional activated sludge (CAS) and advanced membrane bioreactor (MBR) treatment. Zero Fenton sludge discharge: A review of the reuse approach during wastewater treatment with an advanced oxidation process. Optimization of process variables for landfill leachate treatment using an advanced Fenton-based oxidation technique.
Elimination of micropollutants and transformation products from a wastewater treatment plant through pilot-scale ozonation followed by various activated carbon and biological filters. The amount of nutrients received by aquatic ecosystems varies worldwide depending on the characteristics of the ecosystem.
Composition of sewage
Wastewater disposal in a particular region depends on the accessibility of natural water courses in that particular area. Poorly managed human excreta have several harmful effects on the environment, polluting surface waters such as lakes and rivers. Water bodies located in highly populated urban areas have a significant amount of biological oxygen demand contributed mainly by sewage.
Untreated or partially treated urban wastewater consists of a high concentration of nutrients as well as organic matter [5], which after decomposition release additional nutrients. Increasing levels of nutrients, especially nitrogen and phosphorus, in aquatic ecosystems is associated with eutrophication. Some toxic substances including heavy metals have a high concentration in wastewater generated by industries [8].
Due to their non-degradable nature, they tend to exhibit high toxicity in aquatic systems and accumulate in food webs. Human urine is therefore responsible for 50% of the phosphorus load and 80% of the nitrogen load in the sewage [16].
Sewage generation and treatment scenario throughout the world Despite being a major factor in water quality, proper wastewater treatment
Effects of sewage on freshwater biodiversity
- Temperature .1 Physical changes
- Dissolved oxygen .1 Physical changes
- Total suspended solids .1 Physical changes
- Cyanide
- Pharmaceuticals
- Nitrogen
- Heavy metals
- Phosphorus
Aquatic life is maintained under an optimal temperature, and an increase in the average temperature of the water body has ecological consequences, resulting in thermal enhancement [22]. High water temperature also affects the toxicity of some chemicals in the water as well as the sensitivity of living organisms to toxic substances [26, 27]. These losses can have detrimental effects on ecological health, economics, and ecosystem stability [ 35 ].
A high concentration of salts can result in an increase in the salt content of the water body with harmful effects on aquatic organisms and a brackish and salty taste to its consumers. A large amount of dead algae leads to secondary effects in the ecosystem such as eutrophication and disruption of the food chain. Heavy metals constitute one of the most toxic pollutants in aquatic ecosystems due to the harmful effects they exhibit on aquatic biota [55].
Heavy metals in sewage have serious adverse effects on the ecological balance of the aquatic environment, including organisms [56]. A slight increase in the content of this nutrient affects the production of toxins by increasing the growth of algae.
Eutrophication 1 Classification of lakes
- Causes of eutrophication
- Nutrients in aquatic ecosystems
- Symptoms and effects of eutrophication
Most of the phosphorus enters the water body through runoff and erosion during winter storms. Thus, phosphorus flux from diffuse sources may be of little importance in eutrophication of rivers due to the fact that the timing of transfers usually does not overlap with the period of maximum biological demand. This may be partly due to the effects of increased nutrient concentrations in rivers that are less affected, because some factors besides.
Degradation of water quality such as the appearance of red tides or excessive foam on the surface of the water. Increase in the productivity of the ecosystem along with biomass of phytoplankton, macrophytes and harmful algal blooms. Due to the greenish color of water, turbidity and high levels of planktonic algae, the clarity of the water is drastically reduced.
If the water body affected by eutrophication is used for the drinking water supply of a community, it may cause an increase in treatment cost due to prevailing taste and odor problems. Odor problems can arise from aquatic weeds, dead rotting algae, and algal scum.
Conclusion
Economic damage also occurred due to changes in species composition, fish deaths, loss of recreational value and reduction of tourist activities. Human enteric bacteria and viruses in five sewage treatment plants in the Eastern Cape, South Africa. Effects of forest harvesting practices on brook salmonid spawning habitat in the Centennial Creek watershed, British Columbia.
A study on the feasibility of nitrification and denitrification of a complex industrial wastewater with high season. Selection of our books indexed in the Book Citation Index in Web of Science™ Core Collection (BKCI). However, they are known as the largest source of water pollution in the world.
The limitation of this issue is pollution, especially industrial pollution, because industries generate high toxic substances, which can reduce the performance of the treatment [1]. In fact, each process has its advantages and disadvantages; thus the process performance is highly dependent on the nature of the effluent and the flow to be treated.
Treatment of industrial wastewaters
- Physicochemical treatments
- Biological treatments
- Coupled treatments
The literature has demonstrated various physico-chemical and biological processes for the treatment of industrial wastewater. Electrocoagulation is considered a new alternative to chemical coagulation and is a promising process for industrial wastewater treatment [23]. This process has not been demonstrated on a pilot scale for the purification of drinking water.
Adsorption is well known for the treatment of industrial waste water, so it is characterized by its high purification capacity [27]. This technique has the same treatment principle as the previous process, so it is based on the treatment with activated sludge under aerobic conditions. In conclusion, this biotechnology can be the most effective and cheap technique for the treatment of industrial wastewater because it involves the use of the most effective microorganisms for each pollutant type.
In reference [46], they coupled the chemical process of ozone oxidation with the membrane bioreactor for the treatment of tannery effluents. On the other hand, [47] has combined chemical coagulation using ferric chloride with advanced oxidation techniques (photooxidation, homogeneous oxidation and photofenton) for the treatment of industrial wastewater, where coagulation coupled with photofenton is considered the best.
Conclusion
In another study, aluminum sulfate and ferric chloride were used to remove organic carbon and chromium prior to biological treatment of tannery effluents by the SBR. On the other hand, [50] studied the treatment of tannery effluents by coupling 3 processes: 2 anaerobic bioreactors, followed by ozone oxidation, followed by biofiltration. Investigation of direct and alternating current electrocoagulation process for the treatment of distillery industrial effluent: Studies on operation.
Bioaugmentation process for tannery effluent treatment in fez, Morocco: an ecological treatment using novel chromatic bacteria, Water Process Eng. Advanced treatment of pulp and paper mill wastewater by nanofiltration process: effects of operating conditions on membrane fouling, Separ. Biological treatment of wastewater using activated sludge process and sequential batch reactor process - a review, Int.
A combination of chemical and biological processes for the treatment of tannery wastewater in Fez, Morocco. Optimization of Fez Brass Wastewater Treatment with a Sequential Batch Reactor Using Activated Sludge.
