Abstract: A sheet obliquely conveying apparatus is provided with a pair of sheet conveying rollers including a forwardly and reversely rotatable drive roller and a follower roller rotatable in contact with the drive roller, and bearing structure for rotatably supporting the shaft of the follower roller. The dimension of the bearing portion of the bearing structure which supports one end of the shaft of the follower roller is greater generally along the direction of conveyance of a sheet material than the dimension of the bearing portion of the bearing structure which supports the other end of the shaft of the follower roller. The apparatus is further provided with a resilient device generally parallel to the direction of conveyance of the sheet material for pressing the shaft of the follower roller.

Abstract: An apparatus for sludge thickening including a sludge thickener allowing suspended solids of sludge supplied thereto to settle by their own weight while being thickened. The sludge supplied to the sludge thickener is subjected to aeration for a predetermined period of time in a sludge aerator. Aeration of the sludge strips the anaerobic gas, which is attached to the suspended solids in the form of bubbles or dissolved in the sludge, to atmosphere. By aeration of the sludge before being fed to the sludge thickener, floating of the thickened sludge in the thickener can be avoided.

Abstract: A fish is bred in a transparent basin, into which water to be tested is supplied. A light source and a television camera are arranged in such a manner that images of the fish are taken by the camera as a silhouette. From the thus obtained fish images, the frequency distribution of the gravity centers of the fish images in the direction of the depth of water are obtained. The abnormality of the behavior of the fish is detected by comparison of the obtained frequency distribution with a reference distribution provided in advance.

Abstract: An injection control system of a flocculating agent comprises: a flocculating pool into which the inflow liquid flocculating agent is injected and which forms flocs of suspended matters in the liquid; flocculating agent injecting means for injecting the flocculating agent into the flocculating pool; floc image pickup means for photographing a state of the flocs in the flocculating pool and for converting luminance data of the flocs into an electric signal; image recognizing means for recognizing the shape of floc by binarizing the image signal derived from the floc image pickup means on the basis of a luminance level of each pixel; flocculation state deciding means for calculating a characteristic amount of a diameter distribution of the flocs on the basis of the floc shapes recognized by the image recognizing means; and injection amount control means for controlling an amount of the flocculating agent which is injected from the flocculating agent injecting means on the basis of the characteristic amount.

Abstract: The image of microorganisms contained in a sludge of an aeration tank is picked up by an image pickup device having the function of magnifying and picking up microorganism images. Binarizing processing is then made to obtain a binarized image from the resulting gray image, and the binarized image is subjected to thinning processing. The number of pixels of the image left after often the thinning processing is counted to measure the amount of filamentous microorganisms. In this manner, the amount of the filamentous microorganisms can be measured accurately irrespective of their thickness.

Abstract: The fluidizing speed of water inside a flocculation basin of a water treatment process plant is adjusted in accordance with the state of flocculation inside the flocculation basin. The state of flocculation is determined by taking a plurality of pictures within a predetermined period by an ITV disposed inside the basin, recognizing a sufficiently large number of flocs from the pictures thus taken, calculating the particle diameters of the flocs and determining the particle diameter distribution from the result of calculation. The judgement signal is used as a signal for adjusting the water fluidizing speed.

Abstract: A system for controlling a process utilizing filamentous microorganisms is disclosed. The amount of the microorganisms in a medium for growing the filamentous microorganisms is measured, and the control factors associated with the growth of the microorganisms in the medium are controlled on the basis of the measurement of the amount of microorganisms. In the process of measuring the amount of microorganisms, an optical image of a specimen of the medium is formed and scanned two-dimensionally to produce a series of brightness signals corresponding to the brightness distribution of the optical image. The level of the brightness signal is used to determine the amount of the microorganisms contained in the medium.

Abstract: It is necessary for maintaining a good assimilating characteristic of microorganisms upon organic matter in an aeration tank to control a gas flow rate and a return sludge flow rate to optimum values. To this effect, it is necessary to know a concentration of organic matter or a organic load. In the present invention, it is confirmed that carbon dioxide (CO.sub.2) or nitrous oxide (N.sub.2 O) in an exhaust gas from the aeration tank has a correlation with it, and the aeration tank is controlled as N.sub.2 O or CO.sub.2 as an index. Furthermore, it is confirmed that CO.sub.2 formation rate has a good correlation with COD or BOD in the upstream half section of the aeration tank, whereas N.sub.2 O formation rate has a good correlation with COD or BOD in the latter half section thereof along sewage flow direction, and more improved control can be attained by a combination of both CO.sub.2 and N.sub.2 O indices.