GATE ES case studies
GATE ES · Put your knowledge to work in context.
GATE Environmental Science and Engineering (ES) is a national postgraduate engineering entrance examination in India, administered by the Indian Institutes of Technology and IISc on a rotating organising-institute basis. It is used for admission to MTech, MS and PhD programmes in environmental engineering and science, and many public-sector undertakings also shortlist candidates on GATE scores. The GATE ES case studies are 5 cases and about 4,015 words.
1Winter nitrification failure in a sequencing batch reactor
A 4,000 m3/d sequencing batch reactor (SBR) treats municipal sewage mixed with beverage-plant effluent. The design basis was 30 mg/L influent NH4-N, but current influent averages 32 mg/L NH4-N with alkalinity of only 155 mg/L as CaCO3 and pH 7.0.
836 words, about 4 min2Oxygen-corrected particulate compliance at a biomass boiler
A 15 t/h biomass-fired boiler at a food-processing plant has a single high-efficiency cyclone. A stack test reports inlet PM of 123 mg/dscm and outlet PM of 38 mg/dscm, both dry at 15.2% O2.
765 words, about 4 min3Souring of a mesophilic anaerobic digester
An anaerobic digester at a 3,000 m3 mesophilic plant at 35 C receives 60 t/d of food waste and waste-activated sludge, giving an organic loading rate of 4.8 kg VS/m3-d against a design value of 3.0. Over three weeks, pH fell from 7.2 to 6.5, total VFA rose to 7,200 mg/L as acetic acid, alkalinity fell to 2,600 mg/L as CaCO3, and biogas yield dropped to 0.45 m3/kg VS with 48% methane; the design expectation is 0.90 m3/kg VS at 62% methane.
828 words, about 4 min4Environmental flow and cumulative depletion in a run-of-river hydropower reach
A 25 MW run-of-river hydropower project is proposed on a gravel-bed Himalayan river with a catchment of 1,200 km2. The lean-season February flow at the barrage site was 18 m3/s before an upstream project began operating; that project now reduces the flow at the site to 14 m3/s in February.
843 words, about 4 min5Testing a sewage treatment plant's carbon-neutral claim
A 10 million litres per day (MLD) activated sludge plant treats domestic sewage to 12 mg/L total nitrogen; influent total nitrogen is 40 mg/L. The plant uses 0.35 kWh/m3, supplied by a grid with an emission factor of 0.71 kg CO2/kWh.
743 words, about 4 min