Comparison between biological and chemical treatment of wastewater containing nitrogen and phosphorus

Abstract

The present work compared chemical and biological treatment methods to achieve the most efficient treatment for the reduction or elimination of phosphorus and nitrogen from mixed industrial-domestic wastewaters. Batch chemical precipitation by ferric chloride and aluminum sulfate (alum) and a continuous biological suspended growth system were investigated as well as the optimum operating conditions. Concerning chemical treatment, Alum generally achieved a higher removal efficiency percentage for the investigated pollutants compared with FeCl(3) at their optimum pH and dose, especially with chemical oxygen demand (COD). FeCl(3) treatment achieved success only with phosphorus removal, while none of the COD, 5-day biochemical oxygen demand (BOD(5)), total nitrogen (TN) and N-NH(3) achieved acceptable treatment and remained above the maximum permissible limits (MPL). Thus, for such wastewaters, alum is more efficient than FeCl(3). Biological treatment exhibited higher efficiencies, particularly towards nitrogen. TN removal increased by increasing the flow rate to 30-60 l/day. N-NH(3) removal was effective at the slowest flow rate and decreased with increasing flow rate, while an opposite trend was recorded for N-NO(3). At all flow rates, phosphorus levels were below the accepted MPL for discharging into natural systems. Moreover, there was a general trend for the proposed biological treatment to achieve a high removal efficiency for BOD(5) and COD, bringing them to acceptable levels to be released into watercourses safely, especially at the slowest flow rates. Thus, integration between the proposed chemical and biological treatment is highly recommended, producing high-quality effluents acceptable by the environmental law.

Treatment of mixed domestic–industrial wastewater using cyanobacteria

“…Since they are mainly domestic wastewater mixed with some untreated industrial effluents with different proportions, both effluents are dominated by coliform bacteria which are monitored daily at both plants (total and fecal coilform TC and FC). Also the high nitrogen and phosphorus content in both effluents [21] along with the toxic industrial contaminants suppressed the growth of cyanobacteria or any other algae (as no growth was obtained when inoculated in selective medium). These results are consistent with Ernst et al [24] where high concentration of nitrate and phosphate in the mixed domestic-industrial effluents found attributed to the disappearance of cyanobacterial members which require nitrate and phosphate concentrations similar to those found in the natural environment.…”

“…This was shown by Phormidium bohneri [33], the thermophilic cyanobacterium P. laminosum [53], P. tenue and Oscillatoria O-210, isolated from Arctic and Antarctic environments [11,15] and other species [14,15,30,45,48]. Removal of nutrients using cyanobacteria offers, in addition to the high efficiency and low cost, a very simple technology compared to other complicated methodology, in which integration between chemical (coagulation) and biological (activated sludge) was performed to achieve higher efficiencies for nitrogen and phosphorus removal [21].…”

Bioremediation of Industrial Effluent using Cyanobacterial Species: Phormidium mucicola and Anabaena aequalis

“…However, Zn recorded much lower average in the pharmaceutical effluent (0.01 mg/l) compared to that of the textile effluent (0.11 mg/l) while no significant differences were recorded in the Cu levels among the two industry (0.04 and 0.03 mg/l in the textile and pharmaceutical effluents). Nitrogen and phosphorus content in both effluents [26,27,28] along with the toxic industrial contaminants suppressed the growth of cyanobacteria or any other algae.…”

Using Artificial Neural Networks to Solve the Problem Represented by BOD and DO Indicators

“…Oxygen balance is the basis for water contamination modeling; it is described by two indicators of water quality: BOD and DO. Biochemical oxygen demand equals the amount of oxygen used by aerobic microorganisms over a specific time period and conditions, for oxidation of organic compounds in water or waste-water [27]. This value determines the content of biodegradable organic compounds.…”