HA Removal Research Articles

Coagulation performance and floc properties of compound bioflocculant-aluminum sulfate dual-coagulant in treating kaolin-humic acid solution

The coagulation performance and floc properties of compound bioflocculant (CBF)-aluminum sulfate (AS) dual-coagulant were compared with that of AS in the treatment of synthetic kaolin-humic (HA) water. Results showed that AS-CBF dual coagulant was more efficient for HA removal. The floc formation, breakage and reformation were investigated under different dosages and shear rates. Increasing coagulant dosage resulted in the increase of floc growth rate and size. But the floc recoverability was found to decrease with increasing coagulant dosage. Furthermore, flocs formed by AS-CBF (AS dosed firstly) had faster growth rate, larger size and better recoverability than AS and CBF-AS (CBF dosed firstly) in the dosage range investigated. Similar results were obtained when the shear force was changed. Precipitate charge neutralization was a dominant mechanism of AS, and CBF had good adsorption bridging effect. Due to the combination of two advantages, coagulation efficiency could be enhanced significantly.

Abstract 442: Treatment of tumor xenografts in vivo with PEGylated human recombinant hyaluronidase PH20 (PEGPH20) does not increase the metastatic behavior of malignant cells

Abstract Hyaluronan (HA), a nonsulfated glycosaminoglycan, is a significant component of the extracellular matrix of many solid tumors. HA accumulation has been correlated with local invasion, the presence of distal metastasis, higher tumor grade, and poorer overall survival. We have previously demonstrated that sustained HA removal, accomplished with a novel pegylated human recombinant hyaluronidase PH20 (PEGPH20), inhibited tumor growth and enhanced chemotherapeutic activity in HA-rich xenografts (Thompson et al, 2010). As endogenous lysosomal hyaluronidase expression has been implicated as a tumor promoter (Kovar et al, 2006), and exogenous hyaluronidase has been shown to act as a tumor suppressor (Shuster et al, 2002), we aimed to determine whether exogenous PEGPH20 administration alters the metastatic behavior of malignant cells in solid tumors. In a first set of experimental metastasis studies, HA-rich prostate PC3 (2e5) or breast MDA-MB-231 (1e5) cells were intracardially injected (IC) into nude mice (NCR nu/nu). Mice were subsequently treated (>20 min) with a single dose of PEGPH20 (4.5 mg/kg, IV) or vehicle and tumor seeding into organs tracked via bioluminescent imaging over time (n=8/group). In a second set of spontaneous metastasis experiments, prostate PC3 (2e6) or breast MDA-MB-231-Has2 (2e6) cells were injected into either the tibia periosteum or mammary fad pad of nude mice, respectively. MDA-MB-231-Has2 cells are a MDA-MB-231 Has 2 synthase overexpressing clone, shown to overexpress HA both in vitro and in vivo. When PC3 tumors reached ∼375 mm3 (n=11/group), and MDA-MB-231-Has2 reached ∼400 mm3 (n=6/group), mice received PEGPH20 (4.5 mg/kg, IV) or vehicle, q3d × 8 or q3d × 5, respectively. Mice were subsequently sacrificed and lymph node metastasis assessed histologically. Following the initial set of IC experiments, no significant difference in the number or frequency of metastatic nodules, as assessed by bioluminescence, was observed following PEGPH20 treatment versus control in either cell line (PC3, p=0.49; MDA-MB-231, p=0.89). In the second set of experiments, no difference in lymph node metastasis in either cell line was detected (PC3, p=0.68; MDA-MB-231, p=0.55). Finally, no histological evidence of increased metastases was observed in any organs examined (liver, kidney, heart, spleen or lung) following PEGPH20 administration in either study. Taken together, these results suggest exogenous PEGPH20 administration does not impact metastatic behavior in the PC3 prostate, MDA-MB-231 breast or MDA-MB-231-Has2 breast preclinical models. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 442. doi:10.1158/1538-7445.AM2011-442

Effect of pH on the coagulation performance of Al-based coagulants and residual aluminum speciation during the treatment of humic acid–kaolin synthetic water

The fractionation and measurement of residual aluminum was conducted during the treatment of humic (HA)–kaolin synthetic water with Al 2(SO 4) 3, AlCl 3 and polyaluminum chloride (PAC) in order to investigate the effect of pH on the coagulation performance as well as residual aluminum speciation. Experimental results suggested that turbidity removal performance varied according to the following order: AlCl 3 > PAC > Al 2(SO 4) 3. HA removal performance of PAC was better than that of AlCl 3 under acidic condition. The optimum pH range for AlCl 3 and Al 2(SO 4) 3 was between 6.0 and 7.0 while PAC showed stable HA and UV 254 removal capacity with broader pH variation (5.0–8.0). For the three coagulants, majority of residual aluminum existed in the form of total dissolved Al (60–80%), which existed mostly in oligomers or complexes formed between Al and natural organic matter or polymeric colloidal materials. PAC exhibited the least concentration for each kind of residual aluminum species as well as their percentage in total residual aluminum, followed by AlCl 3 and Al 2(SO 4) 3 (in increasing order). Moreover, PAC could effectively reduce the concentration of dissolved monomeric Al and its residual aluminum ratio was the least among the three coagulants and varied little at an initial pH between 7.0 and 9.0.

Influence of pH and ionic strength on removal processes of a sedimentary humic acid in a suspension of vermiculite

Understanding the interactions of humic acids and clay minerals is important for modeling the geochemical fate and transport of nutrients and pollutants in soil and natural waters upon changes of environmental parameters such as ionic strength and pH. This paper describes the adsorption/precipitation properties of a sedimentary humic acid under different conditions of pH and ionic strength in presence of the clay mineral vermiculite. The clay suspension was prepared to have a distribution of grain size composed mainly of particles <63 μm, which is believed to play a major role on transport and fate of adsorbed materials in aquatic environments. The pHs studied were 5.0, 6.0 and 7.0 (±0.1 pH units), in ionic medium of 0.002 and 0.020 mol l−1 KNO3, using initial HA concentrations from 0 to 100 mg l−1. The maximum removal of HA from solution occurred at pH 5.0 in medium of 0.020 mol l−1 KNO3. This removal is mostly due to precipitation, which occurred at similar rates in both ionic strength, so that the additional HA removal at higher ionic strength (0.020 mol l−1 KNO3) was attributed to adsorption. Adsorption processes intensified at higher ionic strength suggest the occurrence of chemical interactions between the interfaces since under these conditions the electrostatic interactions are minimized. A similar effect was observed at pH 6.0, but in this case adsorption prevailed as the removal mechanism in medium of 0.020 mol l−1 KNO3. At pH 7, adsorption is the predominant process removing HA from solution, with increase of adsorption upon decreasing the ionic strength, suggesting that electrostatic attractions play the major role in the adsorption mechanism under these conditions. Comparison of the results obtained using a re-precipitated commercial HA with low N content suggested that the presence of positively charged amine groups increase the adsorption and decrease desorption.