Removal of Excessive Nitrogen and Phosphorus from Urban Wastewater Using Local Microalgal Bloom

The organic content from urban wastewater is treated with various conventional processes efficiently. However, for biological treatment of secondary effluent containing excessive inorganic nitrogen and phosphorus, microalgae can be used. In this study, algal strains have been collected from locally available natural blooms and cultured in a BG-11 medium. Spirulina sp., the blue-green algae, dominant over the other species within the natural bloom, is applied in ten different dosages (0.2-2.5 g/L) to the synthetic wastewater with a 3-day hydraulic retention time. The removal efficiency of nitrate, ammonia, and phosphate have been observed to be about 60%, 30%, and 54% respectively. The highest removal efficiency has been found at 2.5 g/L of microalgae dose. Linear forms of Langmuir and Freundlich isotherms have been used for biosorption modeling, and both isotherms fit well with R2>60% and NRMSE<11% in all cases. Additionally, the separation factor and the adsorption intensity represent the favorability of the biosorption process. Journal of Engineering Science 12(3), 2021, 19-27

Developing Magnetic Material for Remediation of Aquatic Nitrogen Pollution in Water Facilities

Natural organic matter affect water environmental security and posed a potential threat to human health, and thus it has long been considered as a key index to evaluate water treatment performance. Dissolved organic nitrogen is one of the NOM, which produces some disinfection byproducts having more toxic than those carbon-based materials. Coagulation is a key unit of drinking water purification and has received wide attention. However, conventional flocculation technology on removal of DON is so poor that we have to seek more effective improving measurement. The combined use of conventional flocculant and organic polymer can improve treatment efficiency to a certain extent, and enhanced coagulation can also improve the DON removal rate, but their DON removal performance is still not dreamful. At present, there is a lack of systematic research on flocculation to remove DON. Although some achievements have been made, there is still a big gap between the preparation technology of flocculant and the goal of efficient removal of DON in water.For treatment of secondary effluent of industrial wastewater, some studies show that the use of Fe3O4 mainly has the effect of accelerating separation, but the adsorption effect is not good. However, with the synergistic flocculation of amino functionalized Fe3O4 it has a good effect on removing water protein, polysaccharide and humic acid, which can meet the water quality discharge standard and reduce the dosage of flocculant. The above results show that functional nanoparticle materials are of great significance to improve the adsorption and flocculation performance. Therefore, the functional modification of magnetic nanoparticles plays an important role.

Treatment of Actual Winery Wastewater by Fenton-like Process: Optimization to Improve Organic Removal, Reduce Inorganic Sludge Production and Enhance Co-Treatment at Municipal Wastewater Treatment Facilities

Despite many wineries being equipped with onsite wastewater treatment, winery wastewater (WWW) co-treatment at municipal wastewater treatment plants (WWTPs) remains a common practice in wine-making regions. The complex and highly variable nature of WWW can result in negative impacts on WWTP operations, highlighting a need for improved co-treatment methods. In this paper, the feasibility of using the Fenton-like process to pre-treat WWW to enhance co-treatment at municipal WWTPs is assessed. First-stage pre-treatment of the WWW, in the form of dilution and settling or aerobic biological treatment, is used prior to the Fenton-like process. A three-factor BBD experimental design is used to identify optimal reaction time and initial H2O2 and Fe3+ concentrations. Chemical oxygen demand (COD) and total organic carbon (TOC) removal rates are not able to accurately reflect the extent of reaction. Additional trials identified solubilization of particulate COD and TOC, as well as samples handling requirements prior to analysis, as factors affecting the apparent COD and TOC removal rates. Inert suspended solids (ISS) generated during the sample handling process are found to be the response variable best suited to quantifying the extent of the Fenton-like reaction. Maximum ISS generation is observed at initial H2O2 and Fe3+ concentrations of 4000 mg/L and 325 mg/L, however, results suggest that optimal concentrations exceed these values. The impact of adding pre-treated WWW, with and without Fenton-like treatment, to municipal WWTPs’ primary clarifiers and aerobic bioreactors is also assessed via bench-scale trials. Challenges associated with co-treating WWW are found to remain despite the pre-treatment alternatives investigated, including negative impacts on simulated primary and secondary effluent quality. The Fenton-like AOP provides limited opportunity to optimize or enhance co-treatment at municipal WWTPs.

Water reuse in the post-tanning process: minimizing environmental impact of leather production

The post-tanning wastewater is very diversified, as the post-tanning stage should meet the desirable properties of the leather for the final product, with low standardization of the process (compared to beamhouse and tanning). This makes post-tanning effluent reuse less feasible, and reuse in the post-tanning stage still needs to be explored. This work aims to evaluate the reuse of liquid effluents in the post-tanning process. The work methodology consisted of (i) characterization of water streams (groundwater, liquid effluent after primary treatment, and liquid effluent after secondary treatment); (ii) pilot-scale post-tanning tests using groundwater, primary effluent, and secondary effluent; (iii) characterization of the residual baths from pilot-scale tests (pH, conductivity, total solids, chemical oxygen demand, biochemical oxygen demand, chloride, hardness and oil and grease); and (iv) testing the leather obtained for total sulfated ash and organoleptic properties. Results showed that the primary effluent and the secondary effluent could be reused in pilot-scale post-tanning tests. There was an increase in the conductivity of the residual baths when liquid effluents were reused, which confirms the accumulation of salts in the effluents after their reuse.

Common Effluent Treatment Plants Monitoring and Process Augmentation Options to Conform Non-potable Reuse

The stringency in effluent discharge and reuse standards has made it extremely expensive to discharge the effluents safely or reuse them. Therefore, existing wastewater treatment plants should be evaluated and improved or augmented. With this aim, five existing common effluent treatment plants (CETPs) in North India were evaluated, including: the State infrastructure Development Corporation Uttrakhand Limited (SIDCUL) Haridwar, which processes 4.5 Million Liters per day (MLD); the Industrial Model Township (IMT) Manesar Gurgaon, 55 MLD (comprising two streams of 25 and 30 MLD each); the Lawrence Road Industrial Area (LRIA), Delhi, 12MLD (12MLD LRIA); Mayapuri Industrial Area (MIA), Delhi, 12MLD; and the Integrated Industrial Estate (IIE) SIDCUL Pantnagar, 4.0 MLD. These plants were designed to produce treated effluent for non-potable reuse. Results showed that the integrated efficiency (IEa) of all CETPs was 10–20% larger than standard integrated efficiency (IEs), indicating the suitability of the technology, except for 12MLD at MIA CETP where the IEa was 20% lower than IEs, due to the absence of any biological unit in the process. Combined post-treatment of secondary effluent by coagulation, Ultrafiltration (UF), followed by ozonation for CETP SIDCUL Haridwar, was also conducted for its non-potable water reuse. This process was able to reduce Biochemical Oxygen Demand (BOD) by 77%, Chemical Oxygen Demand (COD) by 76%, turbidity by 96%, and Total Suspended Solids (TSS) by 100%. All these parameters confirmed the effluent standards for non-potable reuse. The color was reduced to 4.0 from 42.0 Pt-Co units by the exposure ozone concentration of 8.3 mg/L for up to 4.0 min on the treated water from SIDCUL CETP, which reduced the color by 90% and complied with reuse standards. Hence Combined post treatment by coagulation, UF followed Ozonation of secondary treated effluent could be a better option for the potable reuse of treated water in various domestic and industrial applications.

Removal of antibiotic resistance genes in secondary effluent by slow filtration-NF process

In this study, the combined process of slow filtration and low pressure nanofiltration (NF) has been used to deeply remove the antibiotic resistance genes (ARGs) in a secondary effluent, and the mechanism of ARGs removal has been subsequently explored. It is observed that the optimal filtration rate for the slow filtration without biofilm, slow filtration with the aerobic heterotrophic biofilm, slow filtration with the nitrification biofilm and slow filtration with the denitrification biofilm to remove tet A, tet W, sul I, sul II and DOC is 20 cm/h, and the slow filtration with the aerobic heterotrophic biofilm exhibits the highest removal amount. The slow filtration with biofilms removes a high extent of free ARGs. As compared with the direct NF of the secondary effluent and the slow filtration without biofilm-NF, the slow filtration with the aerobic heterotrophic biofilm-NF combined process exhibits the best ARGs removal effect. The microbial population structure and the high filtration rate in the aerobic heterotrophic biofilmand promote the removal of ARGs. Strengthening the removal of 16S rDNA, intI 1 and DOC can improve the ARGs removal effect of the combined process. Overall, the slow filtration-NF combined process is a better process for removing ARGs.