GATE ES Wastewater management PYQs & Answers

Questions 1–8 of 8. Imported answers require independent review unless marked reviewed.

One million liters per day (MLD) of wastewater with a soluble BOD of 200 mg/L is treated in an activated sludge process. The BOD of treated wastewater is 20 mg/L. The observed yield coefficient of the biological system is 0.35.

The daily biomass generation in the system is ______ kg (an integer value).

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Leachate generated from a legacy municipal solid waste dumping site has to be collected and managed carefully. Which one of the following statements is correct in the context of treatment of leachate from such a site?

Your answerChoose one option.

Setting chamber followed by micro-filtration units are required.

Modular treatment units targeting dissolved organic matter and salts are required.

Only biological treatment units like AS with extended aeration are required.

Only a combination of anaerobic-aerobic treatment units is required.

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For effluents generated by a molasses based distillery and wood based pulp and paper industry, which of the following statement(s) is/are NOT correct?

Your answerSelect all correct options. You can choose more than one.

Both the effluents have dark colour.

Both the effluents have high toxicity.

Both the effluents generally have BOD greater than 15,000 ppm.

Both the effluents have high pH.

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A sewage treatment plant with a capacity of 10 million litres per day (MLD) is treating the sewage through an aerobic biological process. The inlet and outlet BOD are measured as 100 and 30 mg/l, respectively. If the mixed microbial culture has an observed biomass yield of 0.5 g Volatile Suspended Solids (VSS)/g BOD, the sludge production rate (in kg per day, rounded off to one decimal place) when the plant is operating at 80% capacity will be __________.

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A centrifuge is processing 1000 litres per hour of water containing 2 g per litre of suspended solids. The thickened slurry coming out of the centrifuge has solids concentration of 20 g per 100 ml. If the centrifuge has 99% efficiency based on solids separation, the flow rate (in litres per hour, rounded off to one decimal place) of the supernatant stream will be __________.

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A sewage treatment plant (STP) receives sewage at a flow rate of 20000 m³ per day. The sewage has 200 mg/L of suspended solids. Assume 60 % suspended solids are removed in the primary clarifier. The underflow (i.e. sludge) removed from the clarifier contains 5 % solids (by weight).

The daily volume of the sludge generated will be ______ m³ per day.

Assume sludge density = 1000 kg/m³.

Your answerChoose one option.

480

800

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A 900 mm internal diameter sewer is laid at a slope of 0.004 and has an actual flow of 0.15 m³/s. Assuming Manning’s roughness coefficient to be 0.013, the ratio of the actual flow to the flow when the sewer is running full is ______ (rounded off to two decimal places). Take

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A 10 million litres per day (MLD) sewage treatment plant (STP) is based on the Activated Sludge Process (ASP). First, the sewage undergoes primary treatment and the resulting treated sewage has BOD₅ of 140 mg/L concentration. This is further passed through a 1500 m³ capacity aeration tank (in ASP), where the mixed liquor volatile suspended solids (MLVSS) concentration is maintained at 300 mg/L. The concentration of BOD₅ of the treated sewage is 5 mg/L. The Food to Microorganism ratio (F/M) of the ASP is ______ day⁻¹ (rounded off to two decimal places).

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GATE ES Wastewater management PYQs

How to practice Wastewater management

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