Environmental Technology

Mustafa, S.; Murtaza, S.; Naeem, A.; Farina, K.

doi: 10.1080/09593332608618544pmid: 15906486

The chromium(III) phosphate was observed to have a high affinity towards Pb2+ ion and the sorption capacities were found to be in the order: Pb2+ >Cu2+ >Cd2+ >Ni2+. Different characterization methods i.e. FTIR, SEM and EDX were employed to investigate the sorption mechanism of Pb2+ by chromium(III) phosphate, which showed that no new solid phases were present in the residue after sorption of Pb2+. The exchange between protons from the surface and Pb2+ from solutions was found to be responsible for Pb2+ sorption by chromium (III) phosphate.

Garzón-Zúñiga, M.; Lessard, P.; Aubry, G.; Buelna, G.

doi: 10.1080/09593332608618552pmid: 15906487

Biofilters using organic media are known to procure efficient treatment for different types of wastewater, but the nitrogen removal pathways implied are still not well understood. In this study, a lab-scale aerated biofilter using peat and treating pig manure was operated for 180 days, in order to quantify the nitrogen transformations occurring in it. It was shown that stripping was important during the start-up, until nitrification took place. Simultaneous nitrification and denitrification, proved by N2 production, became the principal mechanism after some time. The production of N2O did not seem to come only from heterotrophic denitrification, but also from chemodenitrification and autotrophic denitrification. It has also been found that part of the influent nitrogen was retained in the system during the first 150 days, due to filtration, sorption and assimilation. During the last periods of operation, the nitrogen previously retained has been used by microorganisms, leading to an excessive N2 discharge.

HE, P-J.; Shao, L-M.; Guo, H-D.; LI, G-J.; Lee, D-J.

doi: 10.1080/09593332608618553pmid: 15906488

The municipal solids waste (MSW) collected at Shanghai includes a high proportion of food waste, which is easily hydrolyzed to generate ammonia-nitrogen in leachate. This study investigated the efficiency of nitrogen removal from landfill leachate employing four different treatment processes. The simulated rainfall and direct leachate recycling produced strong leachate with high ammonia-nitrogen content, and resulted in the removal of only a small amount of nitrogen. Although pretreating the leachate using an aerobic reactor removed some nitrogen, most of which was transformed to biomass because of the high organic loading applied. Using the three-compartment system, which comprises a landfill column with fresh MSW, a column with well-decomposed refuse layer as the methane generator, and a nitrifier, the ammonia-nitrogen was converted into nitrogen gas and hence removed. Experimental results demonstrated the feasibility of adopting the three-compartment system for managing nitrogen in landfill leachate generated from high-nitrogen-content MSW.

Wang, J. John; Bishop, P.L.

doi: 10.1080/09593332608618549pmid: 15906489

In an enhanced biological phosphorus reactor (EBPR), most poly-phosphate accumulating microorganisms (PAOs) exist as microbial aggregates, or flocs. Information contributing to a better understanding of the internal structure and function of flocs can lead to improvements in the modeling, design and operation of EBPR systems in wastewater treatment. A phosphate ion-selective microelectrode has been developed and was used to measure the phosphate profiles in flocs. The microelectrode uses cobalt as the sensing material and shows very good selectivity towards orthophosphate ions (H2PO4 −, HPO4 2− and PO4 3−). The potentiometric response showed a linear relationship with the logarithm of phosphate concentrations, with a slope of 31.5 mV per decade change of concentration. The solution pH did not show a significant effect on the microelectrode performance within the pH range of 7.5 ∼ 8.0. The effect of ionic strength was also investigated. Measurements using this microelectrode were made on activated sludge floc samples taken from a municipal wastewater treatment plant.

Vanerkar, A.P.; Satyanarayan, S.; Dharmadhikari, D.M.

doi: 10.1080/09593332608618550pmid: 15906490

Herbal Pharmaceutical wastewater was subjected to physico-chemical treatment using conventional coagulants individually and in combination with different anionic, cationic and nonionic polyelectrolytes. Results indicate cationic polyelectrolyte to be the best polymer. Individually Alum did not give good results but Alum with cationic polymer in the ratio of 300:0.25 mg l−1 resulted in the best removals of Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD) and Suspended Solids (SS) of 64.0%, 69.4% and 80.82% respectively. The next combination which resulted in good removals was Lime: cationic polymer in the ratio of 300:0.20 mg l−1 with COD, BOD, and SS removals of 57.6%, 65.1% and 74.0%, respectively. Overall the studies indicated that the herbal pharmaceutical wastewater needs to be treated by physico-chemical treatment as a primary process to reduce the organic load and increase the performance efficiency of the secondary biological treatment process. This paper discusses in detail the studies carried out using conventional coagulants along with synthetic polyelectrolyte.

Ozdemir, C.; Karatas, M.; Dursun, S.; Argun, M.E.; Dogan, S.

doi: 10.1080/09593332608618551pmid: 15906491

Chromium (VI) is one of the heavy metals in water and wastewater that has the most toxic characteristic. Consequently, it is dangerous for human and environmental health. Various methods are used for removal of the chromium from wastewater, and new methods have been developed in recent years. Recent studies and investigations on the removal of environmental pollution selected methods that were economical, of optimum efficiently and could be carried out easily. In this study, the removal of Cr6+ in the leather industry wastewater is investigated using MnSO4 that was used easily and economically. Experimental studies are performed in two phases. In the first phase, the optimum MnSO4 dose for removal of Cr6+ was determined. In the second phase, the optimum pH was studied. About 96% removal of chromium was launched with 530 mg l−1 MnSO4 dose at pH value 9 in the wastewater sample.

Kim, R-H.; Lee, S.; Lee, J-H.; Kim, Y-M.; Suh, J-Y

doi: 10.1080/09593332608618545pmid: 15906492

Rainwater utilization has potential to recover the hydrological cycle, to buffer extreme run-off situations in the watercourses, and to reduce the costs for water supply in urban areas. However, relatively few works have been done for developing technologies to improve the water quality during rainwater utilization in large cities where the contamination of rainwater is anticipated. Therefore, this study focused on developing technologies for rainwater utilization subsystems including catchment, storage, treatment, infiltration, and use for buildings in urban areas. The rainwater samples collected from roof and roof garden were compared with wet deposition to analyze and identify the major components that may cause problems in rainwater utilization. Based on these results, novel techniques utilizing TiO2, sunlight, and bauxsol to minimize the contamination level by particles, microorganisms, and nutrients were developed for rainwater subsystems and applied to explore their suitability.

Kim, R-H.; Lee, S.; Kim, Y-M.; Lee, J-H.; Kim, S.-K.; Kim, S-G.

doi: 10.1080/09593332608618546pmid: 15906493

Frequent urban floods and insufficient water supply have led to developing technologies for rainwater utilization in order to buffer extreme runoff situations in the watercourses and to provide an ongoing water supply for non-potable use. However, little information is available on the water qualities and runoff properties of collected rainwater in connection with efficient design and maintenance strategies of rainwater utilization systems. In this work, the characteristics of rainwater were investigated in a full-scale rainwater utilization facility in Korea. Samples of runoff rainwater from various catchment surfaces were analyzed for physico-chemical and microbial determinants including metals, nutrients, pH, turbidity, conductivity, and microorganisms. The pollutant concentrations in rainwater storage tank were also monitored to elucidate the impact of input rainwater quality on stored water property. It is likely that particles and total coliforms are major issues in operating rainwater utilization system. However, further studies will be necessary to address the health effect of rainwater in terms of microbial and ecotoxicological measures.

Levasseur, B.; Blais, J-F.; Mercier, G.

doi: 10.1080/09593332608618547pmid: 15906494

This research work focuses on the development of a new process for the decontamination of municipal wastes incinerators fly ashes. The objective of this study was to evaluate different total and selective precipitation methods for metals removal from ash decontamination leachates. The tested options include 1) use of hydrated lime and caustic soda for selective (pH 5.0) and total (pH 8.5) metal precipitation; 2) addition of different chemicals (H3PO4, Na2S and FeCl3) in a pH range from 6.0 to 9.0. Fly ash decontamination assays using alkaline and acid washing steps were initially performed using optimal conditions previously established. Treated fly ashes respected the standards based on the TCLP leaching test for all studied metals and SPLP. Total metal precipitation tests carried out at pH 8.5 achieve removal yields for all metals ≥ 90% using hydrated lime and ≥ 83% using caustic soda. Selective precipitation tests alone at pH 5.0 show removal yields ≥ 97% for Cr and between 75 and 87% for Al and Pb. Moreover, assays carried out using a stoechiometric addition of Na2S have allowed the separation of Cd (≥ 99%) and Zn (≥ 71%) as metal sulphides (CdS and ZnS). From an economical point of view, the most interesting option seems to be the leachates neutralization at pH 7.0 using Ca(OH)2 combined with the reuse of the treated leachates in the fly ash leaching steps. Metal precipitation cost at pH 7.0 has been estimated to be 22.7 CAN$ tct−1 using Ca(OH)2, and 26.7 CAN$ tct-1 using NaOH.

Narita, H.; Isshiki, I.; Funamizu, N.; Takakuwa, T.; Nakagawa, H.; Nishimura, S-I.

doi: 10.1080/09593332608618548pmid: 15906495

Organic matter released from activated sludge bacteria is a considerable issue in the wastewater reclamation process. In this study, we focused 2-keto-3-deoxyoctulosonic acid in the Lipopolysaccharide existed in the gram-negative bacterial cell wall as an index of organic matter released from bacteria, and investigated the fate of 2-keto-3-deoxyoctulosonic acid in the aerated and ultrasonicated activated sludge samples. The results shows 1) 2-keto-3-deoxyoctulosonic acid concentration in the hydrolyzed sample was higher than non-hydrolyzed sample, and this implied that 2-keto-3-deoxyoctulosonic acid existed in the water phase as a monomer and also as a polymer such as Lipopolysaccharide form and their fragments; 2) the value of (2-keto-3-deoxyoctulosonic acid)/(dissolved organic carbon) ratio did not change in the sludge sonication process and was approximately 0.0006, on the other hand, in the bacteria decay process, the ratio varied from zero to approximately 0.0012; 3) the linear relationship was observed between the degraded heterotrophic biomass and the generated 2-keto-3- deoxyoctulosonic acid; and 4) 2-keto-3-deoxyoctulosonic acid might be considered as an index of organic matter originated from activated sludge bacteria cell.