Biological nitrogen and carbon removal in a gravity flow biomass concentrator reactor for municipal sewage treatment

A novel membrane system, the Biomass Concentrator Reactor (BCR), was evaluated as an alternative technology for the treatment of municipal wastewater. Because the BCR is equipped with a membrane whose average poresize is 20 μm (18–28 μm), the reactor requires low-pressure differential to operate (gravity). The effectiveness of this system was evaluated for the removal of carbon and nitrogen using two identical BCRs, identified as conventional and hybrid, that were operated in parallel. The conventional reactor was operated under full aerobic conditions (i.e., organic carbon and ammonia oxidation), while the hybrid reactor incorporated an anoxic zone for nitrate reduction as well as an aerobic zone for organic carbon and ammonia oxidation. Both reactors were fed synthetic wastewater at a flow rate of 71 L d^?1, which resulted in a hydraulic retention time of 9 h. In the case of the hybrid reactor, the recycle flow from the aerobic zone to the anoxic zone was twice the feed flow rate. Reactor performance was evaluated under two solids retention times (6 and 15 d). Under these conditions, the BCRs achieved nearly 100% mixed liquor solids separation with a hydraulic head differential of less than 2.5 cm. The COD removal efficiency was over 90%. Essentially complete nitrification was achieved in both systems, and nitrogen removal in the hybrid reactor was close to the expected value (67%).     

Revisions to the derivation of the Australian and New Zealand guidelines for toxicants in fresh and marine waters

The Australian and New Zealand Guidelines for Fresh and Marine Water Quality are a key document in the Australian National Water Quality Management Strategy. These guidelines released in 2000 are currently being reviewed and updated. The revision is being co-ordinated by the Australian Department of Sustainability, Environment, Water, Population and Communities, while technical matters are dealt with by a series of Working Groups. The revision will be evolutionary in nature reflecting the latest scientific developments and a range of stakeholder desires. Key changes will be: increasing the types and sources of data that can be used; working collaboratively with industry to permit the use of commercial-in-confidence data; increasing the minimum data requirements; including a measure of the uncertainty of the trigger value; improving the software used to calculate trigger values; increasing the rigour of site-specific trigger values; improving the method for assessing the reliability of the trigger values; and providing guidance of measures of toxicity and toxicological endpoints that may, in the near future, be appropriate for trigger value derivation. These changes will markedly improve the number and quality of the trigger values that can be derived and will increase end-users’ ability to understand and implement the guidelines in a scientifically rigorous manner.     

Nutrient and enzymatic changes of hydrolysed tannery solid waste treated with epigeic earthworm Eudrilus eugeniae and phytotoxicity assessment on selected commercial crops

Animal fleshing (ANFL) is the predominant proteinaceous solid waste generated during processing of leather and it is confronting disposal problems. The aim of this study was to assess the potential of epigeic earthworm Eudrilus eugeniae to utilize and transform the fermented ANFL in the solid state (SSF) and submerged state (SmF) into a value added product along a low residence period (25 days). A total of six treatment units containing different waste mixture compositions were established. Fifty healthy and non-clitellated earthworms were introduced in three different treatment containers: control, SSF, and SmF (+worm). Another set of treatment mixtures (control, SSF, SmF) was established without earthworms (?worm) to compare the results. The products were characterized for physico-chemical, enzymatic analysis and seedling growth parameters to compare the differences in the process with and without earthworms. The changes observed in the analytical parameters were in the following order: SSF > SmF > control mixtures (p?<?0.05). The vermicompost showed a significant reduction in heavy metals, total organic carbon and an increase in total Kjeldhal nitrogen as compared to the product untreated by earthworms. The maximum enzymatic activities were observed after 21 days of vermicomposting. The relative seed germination of vermicompost extracts were in the order of tomato (Lycopersicon esculentum) > green gram (Vigna radiata) > cucumber (Cucumis sativus) > bottle gourd (Lagenaria siceraria (Mol.) Standl.) and showed no phytotoxicity effects. The results indicated that the combination of both ANFL hydrolysis through fermentation and vermicomposting is a good alternative to the management of this kind of waste.     

Contamination levels of polychlorinated biphenyls in wild versus cultivated samples of female and male mussels (Mytilus sp.) from the Northwest Coast of Iberian Peninsula—new application for QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) methodology

A newly analytical method based on QuEChERS extraction followed by gas chromatography with mass spectrometry (GC-MS) analysis was developed and validated for the quantification of 18 PCBs in wild (from Matosinhos Beach, Portugal) and cultivated (from Ria de Arousa, Spain) mussel samples, pooled by sex. Wild animals showed higher PCB levels than cultivated mussels, with males from both origins, presenting an upper contamination profile comparing with females. This fact seems to be correlated with few biometric parameters, but other interdependencies, not addressed herein, such as distinct lipid contents between sexes, as a consequence of the gametogenic stage, may also explain this data. Overall, data reiterate the importance of investigating the presence of PCBs in marine biological samples, which can act both as bioindicators of environmental contamination, either as food quality controls for human health.     

R&D Activities,Operating Experience Discussed at Fabric Alternatives Forum

ABSTRACT

Previously reported volatile organic compounds (VOC) radiocarbon (¹⁴C) measurements for 1992 summertime Atlanta, GA, have been compared with chromatographic data and emissions inventory predictions. The chromatographic approach that was used provided a more comprehensive VOC characterization than typically achieved, and the emissions inventory was research-grade level (date-, site-, and time-specific). The comparisons are in general agreement that biogenic emissions contribute only modestly (<10%) to the VOC content of the particular ambient samples that were collected and measured. The choices of sampling site (near city-center) and times (early morning and late evening) are major influences on the results, which consequently should not be regarded as representing the average VOC biogenic impact for the Atlanta area.     

Resource Recovery from Flue Gas Desulfurization Systems

The cost effective benefits of yielding a flue gas desulfurization (FGD) sludge predominantly composed of CaSO₄·2H₂O, have been previously established. The recovery of this material as FGD by-product gypsum has been demonstrated abroad. Recently U.S. wallboard manufacturers have recognized the viability of this recovery practice. Such techno-economic decision making variables as a) by-product specification, b) transportation costs, and c) location of suitable FGD systems enable the recognition of FGD by-product recovery. Recent investigations of resultant solids content and chloride washing reflect the technical possibility of delivering a suitable product. Commercial and economic factors favor recovery based upon rising disposal and transportation costs. Existing and near term proposed systems surface the technical and commercial problems faced by utilities considering recovery.

Generation of an oxidized FGD sludge consisting of 90⁺% CaSO₄·2H₂O and dewatered to 80⁺% solids is technically achievable by air sparging within the FGD system. Although the product is suitable for land disposal, electric power utilities should consider and evaluate by-product recovery. U.S. wallboard manufacturers have established technical criteria for FGD by-product gypsum. Percent CaSO₄·2H₂O, final solids content, particle size, and chloride content are primarily technical parameters. Technology exists within the FGD industry to satisfy these criteria and results are discussed.

Economic factors comparing mining costs, transportation costs, and disposal costs are developed for specific utility projects. Such comparison established generalized financial criteria for a given utility to develop the economic reasonableness of considering FGD byproduct recovery.

End product user perspectives are presented providing electric utilities with a realistic appreciation for by-product recovery potential. Location of existing wallboard plants highlight potential recovery regions. Quality control problems are discussed in terms of generating a by-product rather than a disposable material.     

Comparison of Air Pollutant Emissions from Vaporizing and Air Atomizing Waste Oil Heaters

Information presented in this paper is directed to individuals concerned with emissions from combustion of waste crankcase oil for space heating. Studies were performed to characterize gaseous and particulate emissions and vaporizing pot solid residues resulting from the combustion of waste crankcase oil. Two types of waste oil burners were tested. One was a vaporizing oil burner rated at 35.2 kW (120,000 Btu/h heat input), and the other was an air atomizing oil burner rated at 73.3 kW (250,000 Btu/h heat input). Except for NO_X and SO_X, gaseous emissions were similar to those from conventional distillate oil combustion. NO_X and SO_X emissions were higher due to higher fuel nitrogen and sulfur concentrations. Waste oil from automotive use showed higher inorganic levels than crankcase oil used for truck engine lubrication. Both burner types discharged high levels of metallic species, but the air atomizing unit had much higher stack emission levels than did the vaporizing pot system. Also, particulate loading levels were an order of magnitude higher for the air atomizing burner than for the vaporizing pot burner when firing the waste oils. However, the vaporizing pot burner generated a waste residue containing the majority of its elemental emissions. Elements which exceeded threshold limit values for one or both heaters were cadmium, chromium, cobalt, copper, iron, lead, nickel, phosphorus, and zinc. However, the nickel and much of chromium appeared to be a sampling artifact caused by the stainless steel sampling system.