Basic H2S training in Kochi for Chennai refinery, sewage and effluent teams

Four Chennai settings where the gas collects

Start with the plumbing of the city. Reports put Chennai's sewage treatment capacity at roughly 745 to 764 million litres a day across a dozen or so plants, with the older works at Kodungaiyur, Koyambedu, Nesapakkam and Perungudi being revamped; the sources disagree on exact totals, so treat these as approximate. A news account describes the pumping stations as running round the clock, each with wells for collection, screening and suction. Those wells and screens are enclosed, damp and low, which is where H2S lingers, and the crews who clear them are often employed by contractors rather than the board.

Tanning is the second setting. A 2013 inspection report by the Central Pollution Control Board describes the Pallavaram common effluent treatment plant as one of Tamil Nadu's oldest, set up in 1995 for 149 member tanneries processing goat and sheep hides, with a design flow of 3,000 cubic metres a day. Its listed components include a receiving sump 6 m across and 5 m deep, a screen chamber, equalisation basins and sludge beds, and its chemical list includes hydrochloric acid at about 1.2 lakh litres a year. Tanning effluent can carry sulphide, and acid meeting sulphide is the usual route to H2S, so a deep sump and an acid store in one plant are exactly what a gas-awareness course speaks to. The inspection recorded sulphide at 0.6 mg/l at one stage of treatment.

The refinery is the third. CPCL's Manali complex has a once-through hydrocracker commissioned in 2004 and diesel hydro-desulphurisation units, and a sulphur recovery unit has been commissioned to convert the refinery's hydrogen sulphide gas to elemental sulphur. Sulphur removal is the heart of a modern refinery, which means process operators and shutdown contractors work near equipment that handles the gas by design, and their site rules, not ours, decide who needs the certificate.

Finally, the north coast. Kamarajar Port at Ennore lists a marine liquid terminal handling petroleum products, LPG, black fuel stock and chemicals, with a capacity of 3 million tonnes a year, commissioned in 2009. Tank farms and pipelines of that kind may involve H2S in tank vapour spaces and in cleaning work. We do not know which cargoes at any given jetty do, so ask your employer.

H2S awareness alongside offshore, permit or hazmat courses

Basic H2S answers a narrow question: spotting the gas, using detectors and escape sets, and responding when someone goes down. It does not authorise anyone to enter a sump or tank; that authority comes from your site's permit system. For Chennai candidates the usual pairing is offshore: T-BOSIET gives the transfer and survival induction, and H2S is the half-day add-on that many operators list. For plant and utility staff, permit to work is the natural companion, with first aid for the person who must help a casualty. Where the hazard is chemicals in drums and tankers rather than gas from a process, hazmat training is the wider course.