A polymeric-Al-Zn-Fe (PAZF) coagulant showing high removal of pollutants has been successfully developed using a galvanized slag in earlier works, but it gave less elimination of phosphorus. To improve phosphorus removal, a hybrid organic-Al-Zn-Fe (HOAZF) coagulant was prepared using PAZF and polyacrylamide (PAM) as an organic additive, and then was characterized by scanning electron microscopy (SEM), infrared spectroscopy (IR), X-ray diffraction (XRD), and Zeta potential, respectively. Removing efficiency and mechanism of organophosphorus by HOAZF was probed using jar tests in treating a simulated pesticide wastewater containing dichlorvos (DDVP), compared to that by PAZF and polyaluminum chloride. The results displayed that HOAZF having relative lower Zeta potential (compared to PAZF) exhibited complex surface morphology composited by Al, Zn and Fe and PAM, forming some new crystalline and amorphous substances different from that in PAZF. HOAZF gave higher removal of organophosphorus and far lower dosage than PAZF, and also posed a suitable wider pH range (pH = 7–12 for HOAZF and 10–11 for PAZF, respectively) and suitable wider organophosphorus level range than PAZF. Removing organophosphorus by HOAZF was a simultaneous complex process involving a non-phase transfer of adsorption/bridging/sweeping and a phase transfer of chemical precipitation.

Based on present serious phenomenon of insufficient carbon source in municipal sewage in China, the two kinds of effect of hybrid-fruit-peel (HFP) coagulant (coagulation and external carbon source (ECS)) on treating low carbon source wastewater was studied, mainly compared with that of sodium acetate (NaAc). The feasibility of HFP as an ECS was researched, and then its coagulation behavior, sludge properties, nitrogen removal were studied mainly with aeration mode and sequencing batch reactor (SBR), respectively. The results showed the ration of biochemical oxygen demand (BOD5) to chemical oxygen demand (COD) released from HFP was 0.67−0.76, within the scope of easily biodegradable. Within a short aeration time, HFP posed obvious coagulation behavior. HFP sludge gave larger extracellular polymer (EPS) and lower dehydrogenase activity (DHA) than NaAc. For HFP, much larger size sludge flocs appeared, the connection among the flocs became closer, and the biofacies and number of microorganisms (Opercularia Coaractata, Nematode, Vorticella, etc.) increased significantly. HFP can be used as an excellent ECS for low carbon source wastewater, and probably also have the ability of slow-releasing carbon, and can be applied to municipal sewage or other wastewaters with insufficient carbon source.