Well Slixtisix, one DSLR sensor or one ram drive with pictures contains more toxins than that 365 gallons of developer. If you expose the developer to air and sunlight it oxidizes and becomes neutral in pH, thus becoming nearly harmless. The bacteria in sewage treatment do the rest. The sensor OTOH, has non-biodegradable toxins that leach into the ground water where it is dumped.
That ones sensor contains arsenic and selenium, which are toxic forever. They do not biodegrade.