Polyethersulfone (PES) was blended with poly(D,L-lactide) (PDLLA) to prepare asymmetric membranes using the phase inversion method. The effects of the blend ratios and poly(ethylene glycol) (PEG) as additive on the membrane structure, properties, and performance were investigated. The membranes were characterized by contact angle determination, scanning electron microscopy, porosity measurement, thermogravimetric analysis, degradation tests in compost, and dynamic tests for pure water flux and bakery product wastewater treatment. PES and PEG slightly reduced the membrane contact angle. Increasing the PDLLA concentration in the blend membranes enhanced the membrane degradation in compost and also the membrane porosity. The permeate flux of the membranes was improved, but the rejection of pollution indices did not change noticeably.