Effect of Tertiary Treatment on Chemically Complex Secondary Wastewater

Abstract A feasibility analysis of tertiary treatment for Organic Liquid Agricultural Waste is presented using filamentous algae belonging to the genus Cladophora sp. as an alternative to chemical tertiary treatment. The main advantages of tertiary treatments that use biological systems are the low cost investment and the minimal dependence on environmental variables. In this work we demonstrate that filamentous algae reduces the nutrient load of nitrate (circa 75%) and phosphate (circa 86%) from the organic waste effluents coming from dairy farms after nine days of culture, with the added advantage being that after the treatment period, algae removal can be achieved by simple procedures. Currently, the organic wastewater is discarded into fields and local streams. However, the algae can acquire value as a by-product since it has various uses as compost, cellulose, and biogas. A disadvantage of this system is that clean water must be used to achieve enough water transparency to allow algae growth. Even so, the nutrient reduction system of the organic effluents proposed is friendly to the ecosystem, compared to tertiary treatments that use chemicals to precipitate and collect nutrients such as nitrates and phosphates.

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Costs of tertiary treatment of municipal wastewater by rapid sand filter with coagulants and UV

Water Science & Technology Water Supply ◽

10.2166/ws.2003.0056 ◽

2003 ◽

Vol 3 (4) ◽

pp. 145-152 ◽

Cited By ~ 3

Author(s):

H. Heinonen-Tanski ◽

P. Juntunen ◽

R. Rajala ◽

E. Haume ◽

A. Niemelä

Keyword(s):

Total Phosphorus ◽

Municipal Wastewater ◽

Pilot Scale ◽

Treated Wastewater ◽

Tertiary Treatment ◽

Sand Filter ◽

Physico Chemical ◽

Bathing Waters ◽

Filtration Unit ◽

Microbial Groups

Municipal treated wastewater has been tertiary treated in a pilot-scale rapid sand filter. The filtration process was improved by using polyaluminium coagulants. The sand-filtered water was further treated with one or two UV reactors. The quality changes of wastewater were measured with transmittance, total phosphorus, soluble phosphorus, and somatic coliphages, FRNA-coliphages, FC, enterococci and fecal clostridia. Sand filtration alone without coagulants improved slightly some physico-chemical parameters and it had almost no effect on content of microorganisms. If coagulants were used, the filtration was more effective. The reductions were 88-98% for microbial groups and 80% for total phosphorus. The wastewater would meet the requirements for bathing waters (2,000 FC/100 ml, EU, 1976). UV further improved the hygiene level; this type of treated wastewater could be used for unrestricted irrigation (2.2 TC/100 ml, US.EPA 1992). The improvement was better if coagulants were used. The price for tertiary treatment (filtration + UV) would have been 0.036 Euro/m3 according to prices in 2001 in 22 Mm3/a. The investment cost needed for the filtration unit was 0.020 Euro/m3 (6%/15a). Filtration with coagulants is recommended in spite of its costs, since the low transmittance of unfiltered wastewater impairs the efficiency of the UV treatment.

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Assessment of Microplastics in a Municipal Wastewater Treatment Plant with Tertiary Treatment: Removal Efficiencies and Loading per Day into the Environment

Water ◽

10.3390/w13101339 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1339

Author(s):

Javier Bayo ◽

Sonia Olmos ◽

Joaquín López-Castellanos

Keyword(s):

Wastewater Treatment ◽

Wastewater Treatment Plant ◽

Municipal Wastewater ◽

Removal Rate ◽

Treatment Plant ◽

Source Control ◽

Municipal Wastewater Treatment ◽

Tertiary Treatment ◽

Stable Performance ◽

Wastewater Samples

This study investigates the removal of microplastics from wastewater in an urban wastewater treatment plant located in Southeast Spain, including an oxidation ditch, rapid sand filtration, and ultraviolet disinfection. A total of 146.73 L of wastewater samples from influent and effluent were processed, following a density separation methodology, visual classification under a stereomicroscope, and FTIR analysis for polymer identification. Microplastics proved to be 72.41% of total microparticles collected, with a global removal rate of 64.26% after the tertiary treatment and within the average retention for European WWTPs. Three different shapes were identified: i.e., microfiber (79.65%), film (11.26%), and fragment (9.09%), without the identification of microbeads despite the proximity to a plastic compounding factory. Fibers were less efficiently removed (56.16%) than particulate microplastics (90.03%), suggesting that tertiary treatments clearly discriminate between forms, and reporting a daily emission of 1.6 × 107 microplastics to the environment. Year variability in microplastic burden was cushioned at the effluent, reporting a stable performance of the sewage plant. Eight different polymer families were identified, LDPE film being the most abundant form, with 10 different colors and sizes mainly between 1–2 mm. Future efforts should be dedicated to source control, plastic waste management, improvement of legislation, and specific microplastic-targeted treatment units, especially for microfiber removal.

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