Petrochemicals giant Sasol has denied that it is responsible for pollution in the Vaal river.However, it has admitted struggling to interpret some compliance requirements with regard to regulations on the discharge of waste.According to a report by the Department of Water and Sanitation Department, three of Sasol's waste incinerators were closed after failing to comply.Challenges to complianceThe revelations were made by the company at the second day of the South African Human Rights Commission's (SAHRC) inquiry into the contamination of the Vaal river on Tuesday."Our discharge compliance [has] been good... we may have had challenges here and there, but we have been improving how we discharge our waste as per the stringent licence regulations from the sanitation department", Sasol's environmental affairs manager Bob Kleynjan said.Kleynjan told News24 on the sidelines of the inquiry, that Sasol would rather close shop than deliberately fail to comply with set regulations. Sustainable water manager Martin Ginster, also from Sasol, submitted that frequent amendments to waste management licences also hindered compliance.Sasol said it had agreed, together with the DWS, to research a "better tool" for the discharge licence so that there was better understanding and compliance.Ekurhuleni also at the inquiryThe City of Ekurhuleni also made submissions on Tuesday, after the Emfuleni Local Municipality fingered it at the first session of the inquiry in September as a contributor to the pollution.Despite being the industrial hub of Gauteng, the municipality said that its discharge into streams leading into the Vaal were as per regulations, and that all companies within its parameters complied."All those who do not comply face stringent steps from the municipality, and we hold them to account.. but as far as we are now concerned, everybody is complying as they should," Environmental Affairs head Daniel Masemola said.#VaalInquiry Ginster "We struggle to interpret compliance requirements, and we are often caught on issues which may not be of risk, as we may not have the same understanding of the license." @TeamNews24— Pelane Phakgadi (@PelaneM) November 20, 2018 The municipality also revealed that 224 companies have been licenced to discharge in the streams.Mbali Matiwane said Ekurhuleni also ensured that when offices were closed on holidays, there were staff who remained."We ensure that during December and January holidays, we have staff who take sampling to ensure that companies which discharge into its rivers remain compliant", she said.READ: SA soldiers to step in and rescue Vaal residents from sewageMeanwhile, the South African National Defence force is expected to set up a base in the Vaal on Wednesday, before they start work on addressing the pollution challenge in the area.Sewage flowing from poorly managed drains and poor water treatment infrastructure have contributed to the contamination of water in the river, and locals have complained about sewage flowing into their streets and homes, and of foul smells in the air.The SANDF has been roped in to attend to their concerns.The SAHRC commissioners sitting at the inquiry re expected to conduct visits at discharge sites in the Ekurhuleni Metro, the Emfuleni Local Municipality and at Sasol before the inquiry goes into recess for the year.The commission's Buang Jones says panellists would like to see the extent of the pollution themselves as well as the rate at which organisations contribute.