  In molecular communication (MC), molecules are released from the transmitter
to convey information. This paper considers a realistic molecule shift keying
(MoSK) scenario with two species of molecule in two reservoirs, where the
molecules are harvested from the environment and placed into different
reservoirs, which are purified by exchanging molecules between the reservoirs.
This process consumes energy, and for a reasonable energy cost, the reservoirs
cannot be pure; thus, our MoSK transmitter is imperfect, releasing mixtures of
both molecules for every symbol, resulting in inter-symbol interference (ISI).
To mitigate ISI, the properties of the receiver are analyzed and a detection
method based on the ratio of different molecules is proposed. Theoretical and
simulation results are provided, showing that with the increase of energy cost,
the system achieves better performance. The good performance of the proposed
detection scheme is also demonstrated.
