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In this paper we present a generalised and systematic decision support methodology and tool to identify and evaluate options for facilitated symbiotic development of industrial clusters. Our approach is developed with insight and feedback from with industry, community and Government stakeholders of the Kawerau industrial site in New Zealand to support early stage engagement of diverse stakeholders. The methodology integrates cluster design by superstructure optimisation, the WoodScape techno-economic analysis methodology and Monte Carlo simulation to provide a range of metrics for investment profitability, macroeconomics and environmental impact to suit diverse stakeholder needs. The novelty of the methodology lies in the flexibility of its modular formulation using demand driven models for industrial plants at an appropriately reduced complexity and using recent advances in optimisation technology. Impact of key uncertainties are assessed through post optimisation Monte Carlo simulations. The methodology is applied to three case studies to identify and evaluate new wood processing opportunities for the Kawerau site. The methodology is formulated to be general and can be applied to other industrial clusters.

The above quote from the ‘Mahawansa’; the historical bible of Sri Lanka and the startling statistic of approximately 79% of the run-off escaping into the ocean in the wet zone today, perhaps would partly justify the selection of the title for this chapter. In keeping with the above noble policy statement, the ancient rulers of the country constructed the large irrigation tanks that dot the landscape in the dry zone and the canal network connecting the tanks and agricultural lands to store rain water for irrigation during the dry season. However, most of the precipitation falls outside this catchment area and no major effort is planned to use the bulk of the rainwater during the dry season when water crises precipitate. Consequently the water resource for which every Sri Lankan is paying by way of indirect taxes is wasted through lack of foresight and misplaced priority. It is important that one looks at the freshwater issue in a holistic manner taking into consideration the country’spopulation statistics, geography, climatic patterns, industrialization and agricultural practices.

This article discusses key mechanisms involved in removing 1 mg/L Mn from synthetic wastewaters in constructed wetlands comprising water hyacinth (Eichhornia crassipes (Mart.) Solms) grown under different nutrient levels of 1-fold (28 mg/L and 7.7 mg/L of total nitrogen and total phosphorus, respectively), 2-fold, 1/4-fold, and 1/8-fold. A mass balance was carried out to evaluate the key removal mechanisms. Phytoremediation mainly due to phytoextraction substantially contributed to manganese removal. However, chemical precipitation was absent, suggesting that manganese has a higher solubility in the given average pH (6.2 to 7.1) conditions in constructed wetlands. Bacterial mediated immobilization mechanisms also did not contribute to manganese removal. Sediments constituted a minor sink to manganese, implying that manganese has a poor adsorption potential. Constructed wetlands comprising water hyacinth are effective at removing manganese from wastewaters despite the fact that the plants are grown under higher or lower nutrient conditions.

Biofilm growth and internal structures were investigated by Confocal Scanning Laser Microscopy and fluorescently labeled oligonucleotide probe hybridization. Biofilms on smooth flat surfaces such as glass slides grew as isolated cell clusters. Under a hydraulic linear flow velocity of 1.7 cm/s mature biofilms exhibited a network like structure consisting of large interconnected cell clusters leading to possible three-dimensional mass transport. Smooth curved tube surfaces were also colonized by isolated cell clusters. However a clustered structure was not observed in mature tubular biofilms which grew as a continuum. Under laminar flow conditions, the tubular biofilms had a uniform cell distribution along the depth with a flat surface profile. The dense tubular biofilms produced under turbulent flow had a stratified structure with thickness. Morphologically these had an irregular surface profile with protrusions extending from a thick base layer. The production of extracellular polymeric substances were both cell physiology and growth related. While hydrodynamic condition was shown to be an effective tool for manipulation of biofilm structures, the relationship of the structure to biological activity and process control needs further investigation.

Three fixed bed downflow biological aerated filters were operated at the rates of 5, 10 and 20 m/day under tertiary treatment conditions. A high NH4+−N oxidation rate of 1.75 kg−N/m3 /day was achieved with an effective residence time of 15 minutes. The biofilm biomass density increased with increasing load while the density gradient along the filter bed became narrower with higher filtration rate. Specific biological activity was inversely proportional to the biomass density. Specific overall biological activity and specific nitrifying activity were found to be higher towards the effluent end of filters operated at the rates of 20 and 10 m/day whereas the highest specific nitrification activity was found to be at the feed end of the slowest filter. Introduction of easily biodegradable organic substrate affected the nitrification activity in the slower filters. The above findings suggest that the location of concentrated nitrification activity is filtration rate dependent. Presence of nitrifiers close to the feed end in a fixed bed downflow filter could be a disadvantage in the presence of faster growing heterotrophic activity under influent fluctuating conditions.

A laboratory scale study on Fe and Mn removal in upflow anaerobic bioreactor of a working volume of 20 L with coir fibre as the filter medium was investigated for a period of 312 days. The maximum Fe and Mn levels considered were 10 and 5 mg/L respectively, which are the typical average values of textile effluents subsequent to the primary and secondary treatments. Ten sub-experimental runs were conducted with varying HRTs (5 days to 1 day), ratios of COD:SO2−4 (20 to 3.5), Fe levels (0.005 to 10 mg/L) and Mn levels (0 to 5 mg/L). COD:SO2−4 of 3.5 was identified as the optimum point at which sulphate reducing bacteria (SRBs) out competed methane producing bacteria (MPBs) and further reduction of this ratio caused total and/or significant inhibition of MPBs, thus building sulphate reducing conditions. The effluent contained Fe and Mn below the permissible levels (1.6 and 1.1 mg/L for Fe and Mn, respectively) stipulated by US National Pollution Discharge Elimination System (NPDES) for inland surface waters at HRTs higher than 3 days. Results of the mass balance showed more Fe accumulation (60%) in sediments whereas 27% in the filter media. An opposite observation was noticed for Mn.

Severe contamination of water resources including groundwater with iron (Fe) due to various anthropogenic activities has been a major environmental problem in industrial areas of Sri Lanka. Hence, the use of the obnoxious weed, water hyacinth (Eichhornia crassipes (Mart.) Solms) in constructed wetlands (floating aquatic macrophyte-based plant treatment systems) to phytoremediate Fe-rich wastewaters seems to be an appealing option. Although several studies have documented that hyacinths are good metal-accumulating plants none of these studies have documented the ability of this plant grown under different nutrient conditions to remove heavy metals from wastewaters. This paper, therefore, reports the phytoremediation efficiencies of water hyacinth grown under different nutrient conditions for Fe-rich wastewaters in batch-type constructed wetlands. This study was conducted for 15 weeks after 1-week acclimatization by culturing young water hyacinth plants (average height of 20+/-2cm) in 590L capacity fiberglass tanks under different nutrient concentrations of 1-fold [28 and 7.7mg/L of total nitrogen (TN) and total phosphorous (TP), respectively], 2-fold, 1/2-fold, 1/4-fold and 1/8-fold with synthetic wastewaters containing 9.27Femg/L. Another set-up of hyacinths containing only Fe as a heavy metal but without any nutrients (i.e., 0-fold) was also studied. A mass balance was carried out to investigate the phytoremediation efficiencies and to determine the different mechanisms governing Fe removal from the wastewaters. Fe removal was largely due to phytoremediation mainly through the process of rhizofiltration and chemical precipitation of Fe2O3 and FeOH3 followed by flocculation and sedimentation. However, chemical precipitation was more significant especially during the first 3 weeks of the study. Plants grown in the 0-fold set-up showed the highest phytoremediation efficiency of 47% during optimum growth at the 6th week with a highest accumulation of 6707Femg/kg dry weight. Active effluxing of Fe back to the wastewater at intermittent periods and with time was a key mechanism of avoiding Fe phytotoxicity in water hyacinth cultured in all set-ups. Our study elucidated that water hyacinth grown under nutrient-poor conditions are ideal to remove Fe from wastewaters with a hydraulic retention time of approximately 6 weeks.

Thermal power generating plants, service stations and oil refineries generate oily wastewaters which are recognized to be a severe threat to aquatic environments. Electrocoagulation has received considerable attention lately as a clean technology option yet absence of reactor design criteria and scientific understanding of the complex phenomena involved remain as a drawback to its widespread application. Laboratory experiments were conducted to determine the optimum operating parameters such as electrode type, influent pH, initial oil concentration, electrode polarity change, electrode surface area: reactor volume, current density and electrode spacing on COD removal efficiency. The effective pH for oil removal is dependent on the anode material used. A pH of 4 is suitable when Al is used where as the effect of pH is negligible for iron electrodes. High removal efficiencies are obtained for moderate oil concentrations of 400-500mg/l as COD. The optimum current density and electrode surface area to volume ratio were 46.9 A/m2 and 8.5 m2/m3 respectively. The electrode polarity switch leads to rapid dissolution of the electrodes and improved COD removal efficiency. The developed design parameters enable the design of low cost compact treatment units that could be powered by DC sources for effective oil separation from wastewaters.