Long D. Nghiem, Nadine Oschmann and Andrea I. Schaefer.

Desalination, Vol. 187, No. 1-3, Feb. 2006, pp. 283-290.

Greywater is no doubt a valuable resource that can be used to alleviate water shortage and increase water conservation in individual households. It is particularly important for arid and semi-arid regions like Australia. Treated greywater can be used for many activities within the household such as toilet flushing, garden watering, car washing, or pavement cleansing. This study examines the fouling behaviour of submerged ultrafiltration membranes in greywater recycling under concentration variation of common greywater constituents. The results indicate that the use of ultrafiltration directly for greywater recycling in individual households is promising. As expected, increase in particulate matter concentration results in a thicker cake layer. However, hydraulic resistance of such cake layers depends on the presence of other constituents namely calcium and organic matter, which play a major role in membrane fouling. Fouling increases linearly with organic matter concentration, while the presence of a small amount of calcium may enhance fouling significantly.

Anonymous

Institution of Civil Engineers. Proceedings. Water Management, vol. 159, pp. 103-109, June 2006

On-site wastewater treatment poses a challenging problem for engineers. It requires a balance of appropriate levels of technology and the operational complexity necessary to obtain high-quality effluent together with adequate reliability and simplicity to accommodate infrequent maintenance and monitoring. This review covers how these issues have been addressed in on-site wastewater treatment in Japan (termed johkasou). On-site systems in Japan range from outmoded designs that discharge grey water directly into the environment to advanced treatment units in high-density areas that produce reclaimed water on-site. Japan is a world leader in membrane technologies that have led to the development of on-site wastewater treatment units capable of water-reclamation quality effluent. Alternative ideas being pursued for on-site technologies also include separate waste stream collection, which would provide for more efficient treatment and reuse. Night soil treatment plants, where sludge from on-site systems is treated, are also distinctive to Japan, serving 37 million people. Japan has governmental regulations in place to ensure routine inspections of on-site units; furthermore, subsidies are available to reduce the cost of on-site systems for building owners. Lessons learned in on-site wastewater treatment in Japan have applications worldwide, from regions where water is scarce, to high-density areas in developing countries that currently lack sewer infrastructures.

Troy W. Hartley.

Desalination, Vol. 187, No. 1-3, Feb. 2006, pp. 115-126.

The Water Environment Research Foundation in the United States funded an interdisciplinary and integrative social science study on public perception and participation in water reuse within the US. It employed a three-phased research protocol consisting of 1) literature review and three comprehensive case studies, including interpretive white papers from five different social science disciplines and public health and environmental engineering scientists, 2) a multi-stakeholder workshop to promote integrative, interdisciplinary analysis of the literature and case study findings, and 3) peer-review among twenty-one social science and water resource management experts. The case studies included examples of potable and non-potable reuse, with elements of success and failure. Five themes were identified as critical to building and maintaining public confidence in water resource management and water reuse decision-making: managing information for all stakeholders; maintaining individual motivation and demonstrating organizational commitment; promoting communication and public dialog; ensuring a fair and sound decision-making process and outcome; and building and maintaining trust. The study produced guidance for water resource professionals with a strategy for assessing the community context and developing a principle-based approach to public outreach, education and participation.

V. Keller.

Science of the Total Environment, Vol. 360, No. 1-3, 1 May 2006, pp. 305-318.

Legal and regulatory authorities around the world generally require that risk assessments are undertaken for the licensing of new and existing substances that present high risk to the environment or the human health. This applies to 'down-the-drain' chemicals that are usually found in household products, such as detergents, that are mainly discharged into rivers via sewer systems. However, the data available for these chemicals is often limited due to cost constraints: in particular, concentration time series for works effluent are generally unavailable, even load data for specific works is often scarce. Although a wide range of models are available, there is a general lack of knowledge on their suitability to model the fate of downthe-drain chemicals at the catchment scale. Several models are presented in this review. The models selected are: the Mackay models, EUSES, Mike 11, QUAL2E, TOMCAT and GREAT-ER. Various applications of these models were investigated to investigate their strength and weaknesses. It appears that, where the availability of data is limited, multimedia fate models such as the Mackay models and EUSES may best be applied to estimate the global risk within each media. However, for site-specific risk assessment the GREATER in-stream water quality model was considered to be more appropriate for modelling down-the-drain chemicals, because it accounts for both spatial and temporal variability, while its data requirements are lower than for models such as Mike 11 and QUAL2E.

Scott J. Goetz and Patrick Jantz.

EOS Transactions, American Geophysical Union, Vol. 87, No. 15, 11 Apr. 2006, pp. 149, 152.

The extent, density, and configuration of the built environment-such as buildings, roads, parking lots, and other materials constructed for human use-have an impact on a wide range of biogeochernical and hydrological processes. These built areas, which are impervious to water infiltration, modify hydrology through the combined influence of increased peak flows, reduced base flows, flashier stream hydrographs (decreased lag times between storm events and peak discharge), and changes in bank and streambed erosion [Nilsson et al., 20031. Additionally, increasing impervious cover has long been known to amplify point source pollution discharges into streams, including chemical runoff from parking lots and roads [Schueler, 1994].

Ki-Young Park, Kyu-Hong Ahn, Ki-Pal Kim, Ji Hyang Kweon and Sung-Kyu Maeng.

Environmental Engineering Science, Vol. 22, No. 5, 2005, pp. 557-566.

Wastewater effluents have recently gained a great deal of attention as a new water resource due to the increasing fresh water demand in Korea. The color content was one of the troublesome parameters to reuse wastewater effluents for indirect purposes such as toilet flushing and cleaning buildings in urban areas (which are the most popular reuse methods in Korea). The color removal was investigated with UV radiation and a UV/H2O2 process. The UV/H2O2 process was effective in removing the persistent color in the wastewater effluents. The kinetic rate constants of removal of color in the wastewater effluents were obtained with different initial H2O2 concentration in the UV/H2O2 process. There was an optimum initial concentration of hydrogen peroxide, about 44.3 mg/L H2O2, above which the removal rate of the color decreased. The rate constant showed the maximum value, approximately 0.087min-1. The rate constant of the removal of color in the wastewater was relatively high compared to the humic acid, repeated in previous work. In addition, the color content in wastewater effluents and after each process was characterized with aquatic humic substance concentrations and molecular weight distributions. The results implied that aquatic humic substances were closely related with organic matter, which exhibit color in wastewater effluents. The results also showed that most of the color material in wastewater effluents were present in the organic matter fraction with molecular weight of less than 3 kDa.

A. Gross, N. Azulai, G. Oron, Z. Ronen, M. Arnold and A. Nejidat.

4.World Water Congress: Water and Health, Vol. 52, No. 8, 2005, pp. 161-169.

There is an increasing trend to use greywater for irrigation in households. This is partly due to the notion that greywater is of better quality than wastewater and therefore does not need extensive treatment beyond addressing public health issues. The aim of the study was to evaluate the environmental impact and health risks associated with the use of greywater for irrigation on a small private farm. Over a three-year period, each of three plots on a farm was irrigated with either freshwater, fertilized water, or greywater. Irrigation water and soil from the plots were analyzed for a wide range of chemical and microbial variables. Results suggest that greywater may be of similar quality to wastewater in several parameters such as BOD and faecal coliforms. For some other variables such as boron and surfactants, greywater may even be of worse quality than wastewater. Long-term irrigation of arid loess soil with greywater may result in accumulation of salts, surfactants and boron in the soil, causing changes in soil properties and toxicity to plants. Faecal coliforms did not survive in the soil. Treating greywater before using it for irrigation is recommended, even in places where this is not a requirement.

Helena Palmquist and Jorgen Hanaeus.

Science of the Total Environment, Vol. 348, No. 1-3, 15 Sept. 2005, pp. 151-163.

The objective of this paper is to present the mass flows of a number of selected hazardous substances in raw, separate greyand blackwater from ordinary Swedish households. The Vibyasen housing area was selected for the investigation since its wastewater system has separate flows for grey- and blackwater. Due to the high analytical costs, a limited number of hazardous substances had to be selected and the number of samples restricted. The greywater flow was manually measured and the samples were collected at set time intervals. The blackwater samples were randomly collected from a blackwater tank.

Anonymous

Nickel, Vol. 21, No. 1, Nov. 2005, pp. 5.

When the city of Chattanooga, Tennessee decided to capture and reuse its stormwater to irrigate municipal gardens, urban planners envisioned a water tower that would serve as a monument to this contribution to sustainability. Aesthetics were a key factor in the design, as the tower was to be built in a recently revitalized downtown. Under these circumstances, S30400 stainless steel, containing 8% nickel, won out over more conventional materials, such as lined carbon steel or reinforced concrete, as the building material of choice. Website: www.nickelmagazine.org/tank.

R. A. Fenner and K. Komvuschara.

Journal of Environmental Engineering, Vol. 131, No. 6, June 2005, pp. 850-864.

Ultraviolet (UV) disinfection of greywater has a number of advantages for small scale applications, but the UV disinfection efficiency can be impeded by high levels of particulates and chemicals in the greywater, micro-organism aggregation, and the geometry between the UV lamp and surrounding sleeve leading to suboptimal flow paths through the lamp assembly. Most process models for UV systems are empirical in nature and do not adequately represent the distribution of UV dose that is actually delivered to micro-organisms in a continuous flow system. This paper presents a model which incorporates: (1) variations in micro-organism sensitivity to UV radiation, (2) the variation of dose received in the UV reactor chamber, and (3) the shielding effect of part of the micro-organism population by the presence of particulates. The model is capable of predicting the asymptotic decay observed in bacterial survival curves when organisms are exposed to a UV dose in a greywater matrix and has been calibrated using experimental data on a series of synthetic greywaters of differing composition and validated against a series of real greywater samples. The model compares favorably to other UV disinfection models and allows the influence of water quality parameters such as turbidity, suspended solids, and UV absorbance to be examined. This allows water quality limits to be defined beyond which the UV disinfection of greywater becomes ineffective. Acceptable performance criteria are established for low power UV systems for the treatment of greywater, which have implications for the selection of suitable annular UV reactors.