Interesting idea . Don't know what power source this guy is using to power the heating element , these elements are available in 12 or 24V , a 300 Watt 12V unit will be consuming around 25 Amps, heavy connecting wires would be needed . This setup would perform well with a plastic 200L drum and citric acid providing the solution temp. isn't too high to weaken the drum.
https://www.youtube.com/watch?v=u0T7sy32vLw