Implementation of sustainable sanitation in existing urban areas: long-term strategies for an optimised solution.

If technologies for decentralised sanitation and reuse (DESAR) and for natural stormwater management should at least partially replace existing systems, then intensive reconstruction work becomes essential. A conversion can only be realised successively over a long period due to high construction and financial expenses and requires new strategies. This paper presents the development and practical implementation of a mathematical tool to find an optimised strategy for the realisation of alternative and more decentralised drainage and sanitation concepts in existing urban areas. The succession of construction measures (e.g. the implementation of decentralised greywater recycling) for the whole period of consideration is determined based upon a mathematical optimisation model on the condition that the favoured future state is known. The model describes the complex interdependencies of the urban water and nutrient cycle and enables the minimisation of both financial efforts and ecological impacts on the way toward the future state. The results of the implementation for a rural area in Germany show that the mathematical optimisation is an adequate instrument to support decision-making processes in finding strategies for the realisation of sustainable urban water management.     

Double-step generation of ellipses

The principle of double-step incremental generation of nonparametric curves on a discrete plane is used to develop a double-step algorithm for scan converting ellipses in sixteen separate segments. The algorithm iterates only half as many times as current algorithms, while each iteration demands the same number of operations or slightly fewer operations than M. Pitteway's (1967, 1985) algorithm (previously the fastest one). This marked gain in the speed of scan conversion is due to the fact that the middle pixel in a two-step increment is obtained without computation     

Purification and Properties of β-Glucuronidase from the Muscle of Bombay Duck (Harpodon Nehereus)

Bombay duck muscle β-glucuronidase purified 4200-fold had molecular weight of 160,000 as estimated by gel filtration on Sephadex G-200. The glycoprotein enzyme exhibited dimeric structure on SDS-PAGE and had a pI of 5.0. The enzyme was optimally active at pH 5.2 when phenolphthalein β-D-glucuronide was used as the substrate while with p-nitrophenyl glucuronide the pH optimum was 4.6. Saccharo-1,4-lactone was a potent competitive inhibitor of the enzyme. Heavy metalic ions such as Hg²⁺, Cd²⁺ and Ag⁺ also proved to be inhibitory to the enzyme. Radiation inactivation of the enzyme could be protected in the presence of mercaptoethanol. Sodium chloride activated the enzyme while sodium tripolyphosphate inhibited it.     

Joint Effect of MLSE and Receiver Filters Optimization on Dispersion Robustness of IMDD, DPSK, DQPSK, and Duobinary Modulation

We analyze the effectiveness of a 32-state maximum-likelihood sequence-estimation (MLSE) receiver on chromatic dispersion robustness of optical transmission based on several binary modulation formats: intensity modulation direct detection, differential phase-shift keying, and duobinary line coding. Multilevel differential quadrature phase-shift keying modulation is also analyzed using a four-state 2-bit/symbol joint MLSE processor. For all modulation formats, receiver filters are optimized together with the use of the MLSE technique.     

Biocides used in building materials and their leaching behavior to sewer systems.

There is increasing concern about diffuse pollution of aquatic systems by biocides used in urban areas. We investigated sources and pathways of biocides significant for the pollution of storm water runoff. Main sources seem to be building envelopes, i.e. facades (paints, plasters) and roof sealing membranes. First results from a defined urban catchment drained by a separated sewer system without any agricultural activities reveal a substantial occurrence. Even after the first flush, concentrations of terbutryn, carbendazim, mecoprop as well as Irgarol 1051 and its metabolite exceeded the Swiss water quality standard of 0.1 microg/L. In laboratory experiments, leaching of mecoprop used as a root protection agent in bitumen sheets for roof waterproofing was determined. The concentrations differed in 16 different sheets two orders of magnitude, depending on the product composition. Using optimized products, it is expected to be the most efficient and sustainable way to reduce the environmental impact. To understand transport dynamics and environmental risk, further storm water events will be analyzed. Based on the ongoing project URBIC, first measures will be proposed to limit the release to surface and ground water.