Substrate-inhibited fermenter (Haldane kinetics)

A continuous chemostat where growth is genuinely inhibited at high substrate concentration — the real Haldane mechanism (mu = mu_max*S/(Ks+S+S^2/Ki)), a native solver kinetics option (params['ki']), not a decorative custom block (custom_block structurally can't change stream composition, so faking this through one would misrepresent the reactor's actual material balance). At the same dilution rate a plain Monod fermenter would consume nearly all the feed substrate; here more substrate survives unconverted and less biomass forms, because growth is suppressed in this concentration range — the whole point of modeling inhibition at all. A strongly inhibitory Ki can also make a nominally achievable dilution rate (D < mu_max) physically unreachable and the reactor washes out, since the Haldane mu(S) curve peaks at a finite S and falls again at higher S.